WO2024092171A1 - Method to deliver large genes using virus and a dna recombination system - Google Patents

Method to deliver large genes using virus and a dna recombination system Download PDF

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WO2024092171A1
WO2024092171A1 PCT/US2023/077973 US2023077973W WO2024092171A1 WO 2024092171 A1 WO2024092171 A1 WO 2024092171A1 US 2023077973 W US2023077973 W US 2023077973W WO 2024092171 A1 WO2024092171 A1 WO 2024092171A1
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linked
flanking sequence
sequence
core
itr
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Seongjin Seo
Poppy DATTA
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University Of Iowa Research Foundation
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    • C12N15/09—Recombinant DNA-technology
    • C12N15/63—Introduction of foreign genetic material using vectors; Vectors; Use of hosts therefor; Regulation of expression
    • C12N15/79—Vectors or expression systems specially adapted for eukaryotic hosts
    • C12N15/85—Vectors or expression systems specially adapted for eukaryotic hosts for animal cells
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    • C12N2750/00011—Details
    • C12N2750/14011—Parvoviridae
    • C12N2750/14111—Dependovirus, e.g. adenoassociated viruses
    • C12N2750/14141—Use of virus, viral particle or viral elements as a vector
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    • C12N2800/00—Nucleic acids vectors
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    • C12N2830/00—Vector systems having a special element relevant for transcription
    • C12N2830/36—Vector systems having a special element relevant for transcription being a transcription termination element
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    • C12N2830/00—Vector systems having a special element relevant for transcription
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    • C12N2840/00—Vectors comprising a special translation-regulating system
    • C12N2840/44—Vectors comprising a special translation-regulating system being a specific part of the splice mechanism, e.g. donor, acceptor

Definitions

  • the efficiency and use of the split intein- mediated protein trans-splicing approach is affected by several factors: 1) amino acid residues at the splitting position (protein trans-splicing efficiency varies depending on the amino acid residues adjacent to split inteins), 2) stability and structure of the expressed N- and C-terminal protein fragments (the effect of truncation on protein stability and structure is hard to predict), and 3) subcellular localization of the expressed N- and C-terminal protein fragments (proximity of the protein fragments is required for protein trans-splicing, but co-localization of the N- and the C-terminal fragments may not occur).
  • the disclosure provides a method to assemble up to four viral, e.g., adeno- associated virus (AAV), genomes in vivo in a pre-designed configuration using a DNA recombination system, e.g., the CRE-lox site-specific DNA recombination system.
  • AAV is a safe and efficient gene delivery vehicle for gene therapies, but its packaging capacity is limited to 4.8 kb. This limited packaging capacity precludes its use as a vehicle to deliver large genes.
  • the CRE-lox DNA recombination system is a highly efficient method to recombine DNA molecules.
  • mutant loxP sequences were designed and others selected and used to provide a series of AAV vectors that enable the assembly of multiple AAV vectors in a pre-designed configuration using the CRE recombinase.
  • This method enables the delivery of large genes that exceed the AAV’s packaging capacity, split into up to four AAV vectors, and may be used for (but not limited to) gene therapies requiring large gene delivery.
  • Exemplary genes for delivery to various organs include but are not limited to genes encoding ABCA4, CEP290, USH2A, MYO7A, PCDH15, CACNA1F, CDH23, OTOF, DYSF, ALMS1, DMD and the like.
  • the method is superior to the other approaches because 1) it improves the recombination efficiency, 2) there is very little restriction in terms of selecting split sites, 3) protein fragment structure, stability, and localization are not issues because the reconstitution occurs at the DNA level, and 4) multiple AAV vectors can be assembled in a predetermined configuration. Therefore, the present methods and vectors provide a highly efficient and flexible method to deliver large genes using AAV vectors.
  • the disclosure provides for a set of AAV vectors comprising a first AAV vector having a genome comprising an inverted terminal repeat (ITR) linked to, in one embodiment, a heterologous promoter, linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site, linked to a first recombination site, e.g., a lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; and a second AAV vector having a genome comprising an ITR linked to a second recombination site, e.g., a lox site, comprising a second left flanking sequence, linked to a second core sequence linked to a second right flanking sequence, linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible
  • the disclosure provides a set of AAV vectors comprising a first AAV vector having a genome comprising an ITR linked to, in one embodiment, a heterologous promoter, linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first recombination site, e.g., a lox site, comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second recombination site, e.g., a lox site, comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third recombination site, e.g., a lox site, comprising
  • a set of AAV vectors comprising a first AAV vector having a genome comprising an ITR linked to, in one embodiment, a heterologous promoter, linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first recombination site, e.g., a lox site, comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second recombination site, e.g., a lox site, comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third recombination site, e.g., a lox site, comprising a third left left flank
  • the set further comprises a vector encoding Cre.
  • one of the vectors in the set encodes Cre.
  • the gene encodes ABCA4, USH2A, IFT140, CEP290, MYO7A, PCDH15, CACNA1F, CDH23, or ALMS1, or a variant thereof.
  • each vector in the set is the same serotype.
  • each ITR in the set is from the same serotype.
  • a host cell is provided that is infected with a first AAV vector having a genome comprising an ITR linked to, in one embodiment, a heterologous promoter, linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first recombination site, e.g., a lox site, comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second recombination site, e.g., a lox site, comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third recombination site, e.g., a lox site comprising a
  • the host cell expresses a recombinase, e.g., Cre recombinase.
  • the host cell is infected with a virus that encodes a recombinase, e.g., Cre recombinase.
  • the host cell is infected with a composition comprising all of the vectors.
  • the host cell is a mammalian host cell, e.g., HEK293, HT1080, A549, PER.C6, NIH3T3, PG13, CHO, or HepG2 cells.
  • a method to express a gene in a mammalian cell comprising infecting the cell with a first AAV vector having a genome comprising an ITR linked to, in one embodiment, a heterologous promoter, linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first recombination site, e.g., a lox site, comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; and a second AAV vector having a genome comprising an ITR linked to a second recombination site, e.g., a lox site, comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence
  • a method to express a gene in a mammal comprising administering to the mammal an effective amount of: a first AAV vector having a genome comprising an ITR linked to, in one embodiment, a heterologous promoter, linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first recombination site, e.g., a lox site, comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; and a second AAV vector having a genome comprising an ITR linked to a second recombination site, e.g., a lox site, comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second
  • the mammal is a human.
  • the vectors are systemically administered. In one embodiment, the vectors are locally administered. In one embodiment, the vectors are injected.
  • the gene is a therapeutic gene. In one embodiment, the gene is a prophylactic gene.
  • the mammal has ABCA4-associated retinal degeneration, USH2A-associated Usher syndrome, IFT140-associated retinitis pigmentosa, or CEP290-associated Leber congenital amaurosis.
  • the amount administered prevents, inhibits or treats one or more symptoms of a disease.
  • a composition comprises the vectors that are administered. Brief Description of Figures Figs.1A-1B.
  • Fig. 1A shows non-compatible mutant variants (loxN and lox2272, loxHT1, and loxHT2) of loxP. Mutations in the core element (red) prevent recombination between non-compatible lox sites. Left and right elements are palindromic.
  • Fig.1B shows reaction equilibrium-modifying variants (loxJT15 and loxJTZ17) of loxP. These variants have mutations (underlined) in either left or right elements (but not in both) and are recognized by CRE recombinase. Recombination between LE and RE mutants produces an LE/RE double mutant and a loxP sequence.
  • Figs. 2A-2D Four pairs of new loxP variants that enable sequence- specific, unidirectional recombination.
  • Fig.2A shows the loxN-based pair.
  • the core sequence of loxJT15 and loxJTZ17, which is from loxP, is replaced with that of loxN.
  • Fig.2B shows the lox2272-based pair.
  • the core sequence of loxJT15 and loxJTZ17 is replaced with that of lox2272.
  • Fig.2C shows the loxHT1-based pair.
  • the core sequence of loxJT15 and loxJTZ17 is replaced with that of loxHT1.
  • FIG. 3A is a schematic representation of large gene reconstitution by CRE- lox mediated recombination of two AAV vectors.
  • a gene-of-interest is split in 2 fragments (CDS1 and CDS2) and delivered to target cells via 2 separate AAV vectors.
  • Reconstitution of the gene is achieved by CRE-lox mediated recombination of the two AAV vectors.
  • CRE may be delivered via a separate AAV vector or included in one of the two AAV vectors if space allows.
  • CDS1 and 2 coding sequence 1 and 2
  • EF1 ⁇ human elongation factor-1 ⁇ promoter
  • ITR inverted terminal repeat
  • pA transcription termination signal
  • SD splice donor
  • SA splice acceptor.
  • Fig. 3B shows successful reconstitution and expression of a large gene (ABCA4) by CRE-lox mediated recombination of two AAV vectors.
  • the coding sequence of human ABCA4 is split and delivered to HEK293T cells via two AAV vectors, and the production of full-length ABCA4 protein was confirmed by Western blotting (WB).
  • the ABCA4-N antibody detects the N-terminal half of ABCA4, and the ABCA4-C antibody detects the C-terminal half of ABCA4.
  • Lane 1 ABCA4-N only
  • lane 2 ABCA4-C (with loxJTZ17) only
  • lane 3 ABCA4-C (with loxP) only
  • lane 4 ABCA4-N and -C (with loxJTZ17)
  • lane 5 ABCA4-N and -C (with loxP)
  • lane 6 ABCA4-N and -C (with loxJTZ17)
  • lane 7 ABCA4- N and -C (with loxP)
  • lane 8 expression plasmids encoding full-length ABCA4 transfected.
  • the CRE expression vector was omitted.
  • Figs.4A-4B the CRE expression vector was omitted.
  • FIG. 4A is a schematic representation of large gene reconstitution by CRE- lox mediated recombination of three AAV vectors.
  • a gene-of-interest is split in 3 fragments (CDS1, 2, and 3) and delivered to target cells via 3 separate AAV vectors. Others are the same as in Figure 3.
  • Fig. 4B shows successful reconstitution of a large gene by CRE-lox mediated recombination of three AAV vectors.
  • the coding sequences of GFP, BBS1 (with a HA tag), and LZTFL1 (with a FLAG tag) were used as CDS1, 2, and 3, respectively, and delivered to HEK293T cells to produce GFP-BBS1-LZTFL1 fusion proteins.
  • Cell lysates were subjected to SDS-PAGE followed by Western blotting (WB) using GFP, HA (for BBS1), and LZTFL1 antibodies. Numbers on the right mark the location of protein standards.
  • Lane 1 CDS1 (GFP) only, lane 2: CDS2 (HA-BBS1) only, lane 3: CDS3 (FLAG-LZTFL1) only, lane 4: CDS1 + CDS2, lane 5: CDS1 + CDS3, lane 6: CDS2 + CDS3, lane 7: CDS1 + CDS2 + CDS3, lane 8: CDS1 + CDS2 + CDS3 (without CRE).
  • a CRE expression vector was co-transduced with the indicated vectors. Endogenous LZTFL1 (red arrowhead) was used as a loading control.
  • Figs.5A-5B CRE-lox mediated reconstitution of large genes: four-AAV set.
  • FIG. 5A is a schematic representation of large gene reconstitution by CRE- lox mediated recombination of four AAV vectors.
  • a gene-of-interest is split in 4 fragments (CDS1, 2, 3, and 4) and delivered to target cells via 4 separate AAV vectors. Others are the same as in Figure 3.
  • Fig. 5B shows successful reconstitution of a large gene by CRE-lox mediated recombination of four AAV vectors.
  • the coding sequences of the N-terminal half of IFT140 (with a HA tag), IFT57 (with a MYC tag), BBS5 (with a HA tag), and LZTFL1 (with a FLAG tag) were used as CDS1, 2, 3, and 4, respectively, and delivered to HEK293T cells as described at the top.
  • Cell lysates were collected 72 hours post-transduction and subjected to SDS-PAGE and western blotting (WB).
  • WB western blotting
  • the production of IFT140- IFT57-BBS5-LZTFL1 fusion proteins was examined by using HA (for IFT140 and BBS5), MYC (for IFT57), and LZTFL1 antibodies. Numbers on the right mark the location of protein standards.
  • a CRE expression vector was co-transduced with the indicated vectors. Endogenous LZTFL1 (red arrowhead) was used as a loading control.
  • Fig.6 Deletion of DNA fragments encompassed by 2 compatible lox sites. The presence of 2 (or more) compatible lox sites causes rapid deletion of the intervening sequence by CRE-mediated recombination. The reverse reaction is much slower because it is a two-molecule recombination. The use of non- compatible lox sites prevents the deletion.
  • Figs.7A-7C Lox site variants that enable CRE-dependent recombination of multiple AAV vectors.
  • Fig. 7A Non-compatible mutant variants of loxP.
  • Fig.7C Lox site variants that prevent recombination between non-compatible lox sites and inhibit reverse reactions.
  • the spacer sequences of loxJT15 and loxJTZ17, which are from loxP, are replaced with those of the non-compatible lox sites (loxN, lox2272, loxm7 (not shown), loxHT1, and loxHT2).
  • Figs. 8A-8F shows advantages of the non-compatible, reaction- equilibrium modifying lox sites.
  • Figs. 8A-8C illustrate problems of using only one species of or compatible lox sites to assemble more than two DNA fragments.
  • Fig. 8A The presence of multiple compatible lox sites within a single DNA fragment leads to a rapid excision of intervening sequences.
  • Figs.8D-8F We have devised 3 pairs of novel lox sites by combining non-compatible (lox2272, loxHT1, and loxHT2; (Lee & Saito, 1998; Missirlis et al, 2006; Siegel et al, 2001)) and reaction- equilibrium modifying lox sites (loxJT15 and loxJTZ17; (Thomson et al, 2003)).
  • Non-compatible lox sites do not undergo recombination with each other due to differences in their core sequences.
  • Reaction-equilibrium modifying lox sites suppress reverse reactions due to the presence of mutations in one of the two CRE binding sites (Fig.8F).
  • the hybrid lox sites that we devised are non-compatible with each other and, at the same time, prevent reverse reactions. These lox sites enable the assembly of more than two DNA fragments in a predetermined configuration.
  • Fig.8D Non-compatible lox sites (e.g., loxP and lox2272) prevent the excision of intervening sequences.
  • Fig.8E By employing two or more non- compatible lox sites, one can precisely specify the DNA fragments to recombine.
  • Fig.8F Incorporating reaction-equilibrium modifying lox sites (e.g., loxJT15 and loxJTZ17) enhances the yield of reconstituted DNAs by preventing the disassembly of the reconstituted cassettes (reverse reactions).
  • Figs.9A-B Assessment of compatibility among hybrid lox sites.
  • Fig.9A Schematics of reporter constructs to detect recombination events between loxJT15 (15:P), loxJTZ17:m7 (17:m7), loxJTZ17:HT1 (17:HT1), loxJTZ17:HT2 (17:HT2), loxJTZ17:2272 (17:2272), and loxJTZ17:N (17:N).
  • the names of the reporter constructs (loxP-2272, loxP-N, lox2272-N, loxP-HT2, and lox2272-HT2) are shown on the left. Black hexagons denote stop codons.
  • C290C a 156-bp fragment from human CEP290 C-terminus (aa 2428-2479).
  • Fig.9B The spacers of loxP and lox2272 are fully incompatible with each other and with those of loxm7, loxHT1, and loxHT2.
  • Reporter constructs shown in Fig. 9A were transfected to HEK293T cells with and without a CRE expression vector, and cell lysates were subjected to SDS-PAGE and immunoblotting.
  • C290-C, FLAG, HA, V5, MYC, and ⁇ -actin antibodies were used for immunoblotting.
  • lysate derived from untransfected cells served as the negative control (lane 6), while lysates obtained from cells transfected with MYC-BBS1, FLAG-LZTFL1, and HA- LZTFL1 expression vectors were used as the positive control (lane 12).
  • ⁇ -actin was used as a loading control.
  • Fig. 10 shows the design of the lox site incompatibility reporters. Schematics of loxP-2272 are shown as a representative. In the absence of recombination, GFP+C290C fusion proteins ( ⁇ 35 kDa) are produced and translation stops at the end of C290C due to the presence of a STOP codon.
  • Figs.11A-11B shows the CRE-lox mediated reconstitution of large genes: three-AAV set.
  • Fig.11A Schematic representation of large gene reconstitution by CRE-lox mediated recombination of three AAV vectors.
  • Three gene fragments (CDS1, 2, and 3) are delivered to target cells via 3 separate AAV vectors.
  • CRE recombinase delivered either separately or as a part of the first vector, facilitates the reconstitution of the expression cassette.
  • the use of non-compatible, reaction- equilibrium modifying lox sites prevents the excision of the floxed fragment as well as reverse reactions.
  • the initial 1,923 bp of IFT140 IFT140-N; with an HA tag
  • BBS1, and LZTFL1 were used as CDS1, 2, and 3, respectively.
  • FIG. 11B Reconstitution and expression of IFT140+BBS1+LZTFL1 fusion proteins using three separate AAV vectors.
  • AAV vectors containing IFT140-N (with an HA tag), BBS1, and LZTFL1 were delivered to 293T cells, and the expression of IFT140+BBS1+LZTFL1 fusion proteins was examined by SDS-PAGE and immunoblotting using HA and LZTFL1 antibodies. Numbers on the right mark the location of protein standards.
  • lane 8 CDS1 + CDS2 + CDS3 (without CRE).
  • Endogenous LZTFL1 blue arrowheads
  • FIG. 12A is a schematic representation of large gene reconstitution by CRE-lox mediated recombination of four AAV vectors.
  • a gene-of-interest is split into four fragments (CDS1, 2, 3, and 4) and delivered to target cells via four separate AAV vectors.
  • CDS1, 2, 3, and 4 fragments
  • IFT140-N the initial 1,923 bp of IFT140
  • IFT57 IFT57
  • BBS5 HA tag
  • LZTFL1 coding sequences were used as CDS1, 2, 3, and 4, respectively. Others are the same as in Fig. 11.
  • Others are the same as in Fig. 11.
  • FIG. 12B shows reconstitution and expression of IFT140+IFT57+BBS5+LZTFL1 fusion proteins using four separate AAV vectors.
  • AAV vectors containing IFT140-N (with an HA tag), IFT57, BBS5, and LZTFL1 were delivered to 293T cells, and the expression of IFT140+IFT57+BBS5+LZTFL1 fusion proteins (red arrowheads) was examined by SDS-PAGE and immunoblotting using HA and LZTFL1 antibodies.
  • a CRE expression vector AAV-EF1 ⁇ -CRE
  • Endogenous LZTFL1 served as a loading control (blue arrowhead).
  • Figs.13A-13B CRE-lox mediated reconstitution of ABCA4.
  • Fig.13A is a schematic representation of ABCA4 reconstitution by CRE-lox mediated recombination.
  • the ABCA4 CDS (6,819 bp) was split into two segments (3,405 bp for CDS1 and 3,414 bp for CDS2) and delivered to HEK293T cells via two separate AAV vectors.
  • CRE was delivered via a separate AAV vector.
  • CDS1 and 2 coding sequence 1 and 2
  • EF1 ⁇ human elongation factor-1 ⁇ promoter
  • ITR inverted terminal repeat
  • pA transcription termination signal
  • SD splice donor
  • SA splice acceptor.
  • Fig.13B shows expression of full-length ABCA4 by CRE/lox mediated recombination.
  • Dual AAV-ABCA4 vectors depicted in panel A were delivered to HEK293T cells (serotype AAV2), and the production of full-length ABCA4 protein was confirmed by Western blotting (WB).
  • the ABCA4-N antibody detects the N-terminal half of ABCA4, and the ABCA4-C antibody detects the C-terminal half of ABCA4.
  • Lane 1 ABCA4-N only
  • lane 2 ABCA4-C (with loxJTZ17) only
  • lane 3 ABCA4-C (with loxP) only
  • lane 4 ABCA4-N and -C (with loxJTZ17)
  • lane 5 ABCA4-N and -C (with loxP)
  • lane 6 ABCA4-N and -C (with loxJTZ17)
  • lane 7 ABCA4-N and -C (with loxP)
  • lane 8 expression plasmids encoding full-length ABCA4 transfected.
  • the CRE expression vector was omitted.
  • Figs. 14A-14D the CRE expression vector was omitted.
  • FIG.14A shows schematics of IFT140 reconstitution by CRE-lox mediated recombination of two AAV vectors.
  • Fig.14B shows schematics of IFT140 reconstitution by protein trans-splicing.
  • the immunogen part used to raise the 140-C antibody was marked by a solid line at the bottom.
  • IntN N-terminal gp41 split intein
  • IntC C-terminal gp41 split intein
  • T2A T2A “self-cleaving” peptide.
  • FIG. 14C shows production of full-length IFT140 proteins by CRE-lox mediated recombination and protein trans-splicing approaches in 293T cells.
  • HEK293T cells were transduced with dual AAV vectors depicted in panels A and B (with a CMV promoter), and cell lysates were subjected to analysis by immunoblotting with HA and 140-C antibodies. Asterisks indicate unconjugated IFT140 “half” protein products.
  • Lane 1 no transduction (negative control)
  • lane 2 dual AAV-IFT140 N+C CRE-lox set (with a CMV promoter)
  • lane 3 AAV-IFT140N-IntN only
  • lane 4 AAV-IFT140C-IntC only
  • lane 5 dual AAV-IFT140 N+C split intein set
  • lane 6 pCS2HA-IFT140 plasmid transfected (full-length; positive control).
  • Fig.14D shows production of full-length IFT140 proteins through CRE-lox mediated recombination of dual AAV vectors in mouse retinas.
  • Dual AAV vectors illustrated in panel A were administered via subretinal injection into mouse eyes (serotype: AAV5, dose: 5x109 vs per vector) and retinal protein extracts were subjected to immunoblotting analysis.
  • AAV-IFT140N vectors with both CBh and CMV promoters were injected to explore potential differences in expression levels. Lysates from uninjected eyes were used as a negative control (lanes 1 and 5). ⁇ -actin was used as a loading control.
  • Fig.15A-15B illustrate the IFT140 domain organization and the location of the splitting position.
  • Fig.15A IFT140 domain organization.
  • the N-terminal portion of IFT140 contains 7-blade WD40 repeats, and its C-terminal half consists of nine tetratricopeptide repeats (TPR).
  • Fig.15B AlphaFold-predicted structural model of IFT140 (identifier: AF-Q96RY7-F1). This model suggests the presence of a WD40-like domain situated in the latter part of the N-terminal half.
  • the red arrows indicate the splitting position (D767/C768) for protein trans-splicing.
  • Figs.16A-16C Reconstitution of PCDH15 using the gp41 split intein and the CRE/lox unidirectional DNA recombination approaches in 293T cells.
  • PCDH15 CDS was split at E644/G645 for the CRE/lox set (Fig.16A) and at F926/S927 or at F1035/T1036 for the gp41 sets (Fig. 16B).
  • a signal peptide derived from PCDH15 (N-terminal 26 residues) was added to the N-terminus of IntC to facilitate the extracellular translocation of IntC.
  • PCDH15N antibody recognizes the N-terminal half of the protein.
  • a FLAG tag (red) was added to the C-terminus of the protein.
  • IRES internal ribosome entry site
  • sig pep signal peptide for extracelluar translocation.
  • HEK293T cells were transfected with AAV- PCDH15 vectors as indicated (lanes 1-3: gp41 926/927 set; lanes 4-6: gp41 1035/1036 set; lanes 7-9: CRE/lox set), and cell lysates were subjected to SDS- PAGE and immunoblotting with PCDH15N and FLAG tag antibodies.
  • the single blue arrowhead marks monomeric forms of PCDH15 N-terminal truncated protein products derived from the gp41N vectors, and the green arrowheads indicate C- terminal truncated proteins from the gp41C vectors.
  • Red arrowheads mark the reconstituted full-length PCDH15 proteins.
  • PCDH15 forms homodimers via its extracellular domain (Kazmierczak et al, 2007). Consistent with this, PCDH15 N- terminal truncated proteins showed a strong tendency to form homodimers even under the denaturing conditions of SDS-PAGE (double blue arrowheads).
  • Figs. 17A-17C Reconstitution of CDH23 using the CRE/lox unidirectional DNA recombination approach.
  • Fig. 17A is a schematic of the CDH23 reconstitution using triple AAV-CDH23 vectors.
  • CDH23 CDS (10,065 bp) was split into three pieces (E1: 2,176 bp, E2: 4,077 bp, and E3: 3,812 bp), and the CRE gene was included in the 5’ (E1) vector for self-inactivation after recombination.
  • E1 2,176 bp
  • E2 4,077 bp
  • E3 3,812 bp
  • a T2A “self-cleaving” peptide was used for CRE expression.
  • An HA tag was added to the N-terminus of CDH23 for detection (right after the signal peptide).
  • the loxJT15/loxJTZ17 pair was used for the recombination of E1 and E2 vectors, and the lox15:2272/lox17:2272 pair was used for E2 and E3 vector recombination.
  • Fig. 17B shows Reconstitution of CDH23 by the CRE/lox approach in 293T cells.
  • HEK293T cells were transduced with triple AAV-CDH23 vectors at an MOI of 3x104 (per vector) (lane 1: E1 vector alone; lane 2: E2 vector alone; lane 3: E3 vector alone, lane 4: E1+E3+E3 co-transduced), and cell lysates were subjected to SDS-PAGE and immunoblotting with HA tag antibodies. Lysates from full-length CDH23 expression plasmid transfected cells were used as a positive control (lane 5).
  • FIG.17C shows reconstitution of CDH23 by the CRE/lox approach in mouse retinas.
  • Triple AAV- CDH23 vectors were subretinally administered to wild-type mice as indicated (lane 1: E1 vector alone, lane 2: E2 vector alone, lane 3: E3 vector alone, lanes 4- 7: E1+E2+E3) at the dose of 3x109 vg per vector.
  • Treated eyes were collected 2 weeks post-injection and retinal protein extracts were subjected to SDS-PAGE and immunoblotting. Each lane represents individual eyes.
  • the present invention is composed in one embodiment of AAV vectors containing a series of mutant lox sequences and an AAV vector to express CRE recombinase.
  • the lox site sequences described in this invention were developed by combining 2 classes of loxP variants: 1) non-compatible mutant variants of loxP ( Figures 1 and 2) reaction equilibrium-modifying mutant variants of loxP ( Figure 1B).
  • the canonical loxP site consists of two 13-bp inverted repeats (left and right elements; LE and RE, respectively) separated by an asymmetric 8-bp core/spacer sequence. The asymmetry of the core gives the loxP site directionality.
  • the non-compatible mutant variants of loxP e.g., loxN and lox2272; Figure 1, or lox 66 and lox 71
  • loxP have mutations within the core, and these mutations prevent strand exchange (and consequently recombination) between non-compatible lox sites while allowing recombination between homologous sites (Lee and Saito,1998); Siegel et al., 2001; Livet et al., 2007).
  • the reaction equilibrium-modifying mutant variants of loxP have mutations within the either LE or RE but not in both (Thomson et al., 2003; Albert et al., 1995). These single-element mutations do not affect the binding of CRE to the lox site, and recombination between these mutant lox sites is as efficient as wild-type loxP sites. However, recombination between LE and RE single mutants produces an LE/RE double mutant and a canonical loxP site. The presence of mutations in both LE and RE significantly reduces the affinity of CRE to the lox site, making LE/RE double mutants a poor substrate of CRE.
  • the loxN- based pair ( Figure 2A) was generated by replacing the core sequence of loxJT15 and loxJTZ17, which is derived from the canonical loxP, with that of loxN.
  • the lox2272-based pair ( Figure 2B) was generated by replacing the core sequence of loxJT15 and loxJTZ17 with that of lox2272.
  • the loxHT1- and the loxHT2-based pairs were generated by replacing the core of loxJT15 and loxJTZ17 with that of loxHT1 and loxHT2, respectively ( Figure 2C and D).
  • these new lox site pairs and the original loxJT15:loxJTZ17 pair have non- compatible core sequences, these 5 pairs do not recombine with heterologous pairs and therefore can be used to simultaneously mediate up to 5 sequence-specific recombination reactions.
  • 3 sets of AAV vectors are described that contain the aforementioned 3 of the 5 mentioned pairs of mutant lox sites to deliver up to 16- kb of genes.
  • the first set is composed of two AAV vectors to deliver up to 8 kb.
  • the second and the third sets are composed of 3 and 4 AAV vectors, respectively, to deliver up to 12 kb and 16 kb.
  • the CRE expression cassette may be delivered via a separate AAV vector or included in one of the AAV vectors to deliver cargo genes if space allows.
  • AAV refers to adeno-associated virus, and may be used to refer to the naturally occurring wild-type virus itself or derivatives thereof. The term covers all subtypes, serotypes and pseudotypes, and both naturally occurring and recombinant forms, except where required otherwise.
  • the AAV genome is built of single stranded DNA, and comprises inverted terminal repeats (ITRs) at both ends of the DNA strand, and two open reading frames: rep and cap, encoding replication and capsid proteins, respectively.
  • ITRs inverted terminal repeats
  • AAVs can be made with a variety of different serotype capsids which have varying transduction profiles or, as used herein, “tropism” for different tissue types.
  • serotype refers to an AAV which is identified by and distinguished from other AAVs based on capsid protein reactivity with defined antisera, e.g., AAV1, AAV2, AAV3, AAV4, AAV5, AAV6, AAV7, AAV8, AAV9, and AAVrh10.
  • serotype AAV2 is used to refer to an AAV which contains capsid proteins encoded from the cap gene of AAV2 and a genome containing 5' and 3' ITR sequences from the same AAV2 serotype.
  • Pseudotyped AAV refers to an AAV that contains capsid proteins from one serotype and a viral genome including 5'-3' ITRs of a second serotype.
  • Pseudotyped rAAV would be expected to have cell surface binding properties of the capsid serotype and genetic properties consistent with the ITR serotype.
  • Pseudotyped rAAV are produced using standard techniques described in the art.
  • the term “about” is used herein to mean a value that is ⁇ 10% of the recited value.
  • administering is meant a method of giving a dosage of a composition described herein (e.g., rAAVs or a pharmaceutical composition thereof) to a subject.
  • compositions utilized in the methods described herein can be administered by any suitable route, including, for example, by inhalation, nebulization, aerosolization, intranasally, intratracheally, intrabronchially, orally, parenterally (e.g., intravenously, subcutaneously, or intramuscularly), orally, nasally, rectally, topically, or buccally.
  • a composition described herein is administered in aerosolized particles intratracheally and/or intrabronchially using an atomizer sprayer (e.g., with a MADgic® laryngo- tracheal mucosal atomization device).
  • the compositions utilized in the methods described herein can also be administered locally or systemically.
  • control element or “control sequence” is a nucleotide sequence involved in an interaction of molecules that contributes to the functional regulation of a polynucleotide, including replication, duplication, transcription, splicing, translation, or degradation of the polynucleotide.
  • the regulation may affect the frequency, speed, or specificity of the process, and may be enhancing or inhibitory in nature.
  • Control elements known in the art include, for example, transcriptional regulatory sequences such as promoters and enhancers.
  • a promoter is a DNA region capable under certain conditions of binding RNA polymerase and initiating transcription of a coding region usually located downstream (in the 3' direction) from the promoter. Promoters include AAV promoters, e.g., P5, P19, P40 and AAV ITR promoters, as well as heterologous promoters.
  • An “expression vector” is a vector comprising a region which encodes a polypeptide of interest, and is used for effecting the expression of the protein in an intended target cell.
  • An expression vector also comprises control elements operatively linked to the encoding region to facilitate expression of the protein in the target.
  • control elements and a gene or genes to which they are operably linked for expression is sometimes referred to as an “expression cassette,” a large number of which are known and available in the art or can be readily constructed from components that are available in the art.
  • a “gene” refers to a polynucleotide containing at least one open reading frame that is capable of encoding a particular protein after being transcribed and translated.
  • the term “gene delivery” refers to the introduction of an exogenous polynucleotide into a cell for gene transfer, and may encompass targeting, binding, uptake, transport, localization, replicon integration and expression.
  • gene transfer refers to the introduction of an exogenous polynucleotide into a cell which may encompass targeting, binding, uptake, transport, localization and replicon integration, but is distinct from and does not imply subsequent expression of the gene.
  • gene expression or “expression” refers to the process of gene transcription, translation, and post-translational modification.
  • a “helper virus” for AAV refers to a virus that allows AAV (e.g., wild- type AAV) to be replicated and packaged by a mammalian cell.
  • helper viruses for AAV are known in the art, including adenoviruses, herpes viruses and poxviruses such as vaccinia.
  • the adenoviruses encompass a number of different subgroups, although Adenovirus type 5 of subgroup C is most commonly used.
  • Numerous adenoviruses of human, non-human mammalian and avian origin are known and available from depositories such as the ATCC.
  • Viruses of the herpes family include, for example, herpes simplex viruses (HSV) and Epstein-Barr viruses (EBV), as well as cytomegaloviruses (CMV) and pseudorabies viruses (PRV); which are also available from depositories such as ATCC.
  • HSV herpes simplex viruses
  • EBV Epstein-Barr viruses
  • CMV cytomegaloviruses
  • PRV pseudorabies viruses
  • “Heterologous” means derived from a genotypically distinct entity from that of the rest of the entity to which it is compared.
  • a polynucleotide introduced by genetic engineering techniques into a different cell type is a heterologous polynucleotide (and, when expressed, can encode a heterologous polypeptide).
  • “Host cells,” “cell lines,” “cell cultures,” “packaging cell line” and other such terms denote eukaryotic cells, e.g., mammalian cells, such as human cells, useful in the present disclosure. These cells can be used as recipients for recombinant vectors, viruses or other transfer polynucleotides, and include the progeny of the original cell that was transduced. It is understood that the progeny of a single cell may not necessarily be completely identical (in morphology or in genomic complement) to the original parent cell.
  • an “isolated” plasmid, virus, or other substance refers to a preparation of the substance devoid of at least some of the other components that may also be present where the substance or a similar substance naturally occurs or is initially prepared from.
  • an isolated substance may be prepared by using a purification technique to enrich it from a source mixture. Enrichment can be measured on an absolute basis, such as weight per volume of solution, or it can be measured in relation to a second, potentially interfering substance present in the source mixture. Increasing enrichments of the embodiments of this disclosure are increasingly more some. Thus, for example, a 2-fold enrichment is some, 10-fold enrichment is more some, 100-fold enrichment is more some, 1000-fold enrichment is even more some.
  • operably linked refers to a physical or functional juxtaposition of the components so described as to permit them to function in their intended manner. More specifically, for example, two DNA sequences operably linked means that the two DNAs are arranged (cis or trans) in such a relationship that at least one of the DNA sequences is able to exert a physiological effect upon the other sequence.
  • an enhancer and/or a promoter can be operably linked with a transgene (e.g., a therapeutic transgene).
  • Packaging refers to a series of subcellular events that results in the assembly and encapsidation of a viral vector, particularly an AAV vector.
  • polynucleotide refers to a polymeric form of nucleotides of any length, including deoxyribonucleotides or ribonucleotides, or analogs thereof.
  • a polynucleotide may comprise modified nucleotides, such as methylated or capped nucleotides and nucleotide analogs, and may be interrupted by non- nucleotide components. If present, modifications to the nucleotide structure may be imparted before or after assembly of the polymer.
  • polynucleotide refers interchangeably to double- and single-stranded molecules. Unless otherwise specified or required, any embodiment of the disclosure described herein that is a polynucleotide encompasses both the double-stranded form and each of two complementary single-stranded forms known or predicted to make up the double-stranded form.
  • nucleic acid refers to a deoxyribonucleotide or ribonucleotide polymer, in linear or circular conformation, and in either single-or double-stranded form.
  • polypeptide and “protein” are used interchangeably herein to refer to polymers of amino acids of any length.
  • polypeptides such as “ABCA4” and the like, when discussed in the context of gene therapy and compositions therefor, refer to the respective intact polypeptide, or any fragment or genetically engineered derivative thereof that retains the desired biochemical function of the intact protein.
  • references to genes for use in gene therapy typically referred to as “transgenes” to be delivered to a recipient cell, include polynucleotides encoding the intact polypeptide or any fragment or genetically engineered derivative possessing the desired biochemical function.
  • composition any composition that contains a therapeutically or biologically active agent (e.g., a polynucleotide comprising a transgene or a portion thereof), either incorporated into a viral vector (e.g., an rAAV vector) or independent of a viral vector (e.g., incorporated into a liposome, microparticle, or nanoparticle)) that is suitable for administration to a subject.
  • a therapeutically or biologically active agent e.g., a polynucleotide comprising a transgene or a portion thereof
  • a viral vector e.g., an rAAV vector
  • independent of a viral vector e.g., incorporated into a liposome, microparticle, or nanoparticle
  • diluent, excipient, carrier, or adjuvant is meant a diluent, excipient, carrier, or adjuvant which is physiologically acceptable to the subject while retaining the therapeutic properties of the pharmaceutical composition with which it is administered.
  • Recombinant as applied to a polynucleotide means that the polynucleotide is the product of various combinations of cloning, restriction and/or ligation steps, and other procedures that result in a construct that is distinct from a polynucleotide found in nature.
  • a recombinant virus is a viral particle comprising a recombinant polynucleotide.
  • the terms respectively include replicates of the original polynucleotide construct and progeny of the original virus construct.
  • recombinant adeno-associated virus (AAV)” or “rAAV vector” is meant a recombinantly-produced AAV or AAV particle that comprises a polynucleotide sequence not of AAV origin (e.g., a polynucleotide comprising a transgene, which may be operably linked to one or more enhancer and/or promoters) to be delivered into a cell, either in vivo, ex vivo, or in vitro.
  • the rAAV may use naturally occurring capsid proteins from any AAV serotype.
  • non-naturally occurring capsids may be used in the rAAVs described herein.
  • reference is meant any sample, standard, or level that is used for comparison purposes.
  • a “normal reference sample” or a “wild-type reference sample” can be, for example, a sample from a subject not having the disorder (e.g., retinal dysfunction).
  • a “positive reference” sample, standard, or value is a sample, standard, value, or number derived from a subject that is known to have a disorder, which may be matched to a sample of a subject by at least one of the following criteria: age, weight, disease stage, and overall health.
  • the terms “subject” and “patient” are used interchangeably herein to refer to any mammal (e.g., a human, a primate, a cat, a dog, a ferret, a cow, a horse, a pig, a goat, a rat, or a mouse).
  • the subject is a human.
  • a “terminator” refers to a polynucleotide sequence that tends to diminish or prevent read-through transcription (i.e., it diminishes or prevent transcription originating on one side of the terminator from continuing through to the other side of the terminator).
  • the degree to which transcription is disrupted is typically a function of the base sequence and/or the length of the terminator sequence.
  • transcriptional termination sequences are specific sequences that tend to disrupt read-through transcription by RNA polymerase, presumably by causing the RNA polymerase molecule to stop and/or disengage from the DNA being transcribed.
  • sequence-specific terminators include polyadenylation (“polyA”) sequences, e.g., SV40 polyA.
  • polyA polyadenylation
  • insertions of relatively long DNA sequences between a promoter and a coding region also tend to disrupt transcription of the coding region, generally in proportion to the length of the intervening sequence. This effect presumably arises because there is always some tendency for an RNA polymerase molecule to become disengaged from the DNA being transcribed, and increasing the length of the sequence to be traversed before reaching the coding region would generally increase the likelihood that disengagement would occur before transcription of the coding region was completed or possibly even initiated.
  • Terminators may thus prevent transcription from only one direction (“uni-directional” terminators) or from both directions (“bi-directional” terminators), and may be comprised of sequence- specific termination sequences or sequence-non-specific terminators or both.
  • a variety of such terminator sequences are known in the art; and illustrative uses of such sequences within the context of the present disclosure are provided below.
  • a “therapeutic gene,” “prophylactic gene,” “target polynucleotide,” “transgene,” “gene of interest” and the like generally refer to a gene or genes to be transferred using a vector.
  • rAAV vector which vector is flanked by inverted terminal repeat (ITR) regions and thus can be replicated and encapsidated into rAAV particles.
  • ITR inverted terminal repeat
  • Target polynucleotides can be used in this disclosure to generate rAAV vectors for a number of different applications.
  • polynucleotides include, but are not limited to: (i) polynucleotides encoding proteins useful in other forms of gene therapy to relieve deficiencies caused by missing, defective or sub-optimal levels of a structural protein or enzyme; (ii) polynucleotides that are transcribed into anti-sense molecules; (iii) polynucleotides that are transcribed into decoys that bind transcription or translation factors; (iv) polynucleotides that encode cellular modulators such as cytokines; (v) polynucleotides that can make recipient cells susceptible to specific drugs, such as the herpes virus thymidine kinase gene; (vi) polynucleotides for cancer therapy, such as E1A tumor suppressor genes or p53 tumor suppressor genes for the treatment of various cancers; and (vii) polynucleotides for gene editing (e.g., CRISPR).
  • CRISPR CRISPR
  • the transgene in a recipient host cell it is in one embodiment operably linked to a promoter, either its own or a heterologous promoter.
  • a promoter either its own or a heterologous promoter.
  • suitable promoters are known in the art, the choice of which depends on the desired level of expression of the target polynucleotide; whether one desires constitutive expression, inducible expression, cell-specific or tissue-specific expression, etc.
  • the rAAV vector may also contain a selectable marker.
  • therapeutically effective amount is meant the amount of a composition administered to improve, inhibit, or ameliorate a condition of a subject, or a symptom of a disorder or disease, in a clinically relevant manner. Any improvement in the subject is considered sufficient to achieve treatment.
  • an amount sufficient to treat is an amount that reduces, inhibits, or prevents the occurrence or one or more symptoms of a disease or disorder or is an amount that reduces the severity of, or the length of time during which a subject suffers from, one or more symptoms of the disease or disorder (e.g., by at least about 10%, about 20%, or about 30%, or by at least about 50%, about 60%, or about 70%, or by at least about 80%, about 90%, about 95%, about 99%, or more, relative to a control subject that is not treated with a composition described herein).
  • An effective amount of the pharmaceutical composition used to practice the methods described herein varies depending upon the manner of administration and the age, body weight, and general health of the subject being treated.
  • a "therapeutically effective amount” refers to an amount effective, at dosages and for periods of time necessary, to achieve the desired therapeutic result.
  • a therapeutically effective amount is also one in which any toxic or detrimental effects of the vector(s)are outweighed by the therapeutically beneficial effects.
  • an "effective amount” or a “therapeutically effective amount” of a set of vectors refers to an amount of the set that alleviates, in whole or in part, symptoms associated with the disorder or condition, or halts or slows further progression or worsening of those symptoms, or prevents or provides prophylaxis for the disorder or condition, e.g., an amount that is effective to prevent, inhibit or treat in the individual one or more symptoms.
  • Transduction or “transducing” as used herein, are terms referring to a process for the introduction of an exogenous polynucleotide, e.g., a transgene in rAAV, into a host cell leading to expression of the polynucleotide, e.g., the transgene in the cell.
  • the process generally includes 1) endocytosis of the AAV after it has bound to a cell surface receptor, 2) escape from endosomes or other intracellular compartments in the cytosol of a cell, 3) trafficking of the viral particle or viral genome to the nucleus, 4) uncoating of the virus particles, and generation of expressible double stranded AAV genome forms, including circular intermediates.
  • the rAAV expressible double stranded form may persist as a nuclear episome or optionally may integrate into the host genome.
  • the alteration of any or a combination of endocytosis of the AAV after it has bound to a cell surface receptor, escape from endosomes or other intracellular compartments to the cytosol of a cell, trafficking of the viral particle or viral genome to the nucleus, or uncoating of the virus particles, and generation of expressive double stranded AAV genome forms, including circular intermediates, may result in altered expression levels or persistence of expression, or altered trafficking to the nucleus, or altered types or relative numbers of host cells or a population of cells expressing the introduced polynucleotide.
  • Altered expression or persistence of a polynucleotide introduced via rAAV can be determined by methods well known to the art including, but not limited to, protein expression, e.g., by ELISA, flow cytometry and Western blot, measurement of DNA and RNA production by hybridization assays, e.g., Northern blots, Southern blots and gel shift mobility assays, or quantitative or non-quantitative reverse transcription, polymerase chain reaction (PCR), or digital droplet PCR assays.
  • protein expression e.g., by ELISA, flow cytometry and Western blot
  • hybridization assays e.g., Northern blots, Southern blots and gel shift mobility assays
  • PCR polymerase chain reaction
  • Treatment of an individual or a cell is any type of intervention in an attempt to alter the natural course of the individual or cell at the time the treatment is initiated, e.g., eliciting a prophylactic, curative or other beneficial effect in the individual.
  • treatment of an individual may be undertaken to decrease or limit the pathology caused by any pathological condition, including (but not limited to) an inherited or induced genetic deficiency, infection by a viral, bacterial, or parasitic organism, a neoplastic or aplastic condition, or an immune system dysfunction such as autoimmunity or immunosuppression.
  • Treatment includes (but is not limited to) administration of a composition, such as a pharmaceutical composition, and administration of compatible cells that have been treated with a composition.
  • Treatment may be performed either prophylactically or therapeutically; that is, either prior or subsequent to the initiation of a pathologic event or contact with an etiologic agent. Treatment may reduce one or more symptoms of a pathological condition. Detecting an improvement in, or the absence of, one or more symptoms of a disorder, indicates successful treatment. For example, “treating” or “treatment” within the meaning herein refers to an alleviation of symptoms associated with a disorder or disease, “inhibiting” means inhibition of further progression or worsening of the symptoms associated with the disorder or disease, and “preventing” refers to prevention of the symptoms associated with the disorder or disease.
  • a “variant” refers to a polynucleotide or a polypeptide that is substantially homologous to a native or reference polynucleotide or polypeptide.
  • a variant polynucleotide may be substantially homologous to a native or reference polynucleotide, but which has a polynucleotide sequence different from that of the native or reference polynucleotide because of one or a plurality of deletions, insertions, and/or substitutions.
  • a variant polypeptide may be substantially homologous to a native or reference polypeptide, but which has an amino acid sequence different from that of the native or reference polypeptide because of one or a plurality of deletions, insertions, and/or substitutions.
  • Variant polypeptide-encoding polynucleotide sequences encompass sequences that comprise one or more additions, deletions, or substitutions of nucleotides when compared to a native or reference polynucleotide sequence, but that encode a variant protein or fragment thereof that retains activity.
  • a wide variety of mutagenesis approaches are known in the art and can be applied by a person of ordinary skill in the art.
  • a variant polynucleotide or polypeptide sequence can be at least 80%, at least 85%, at least at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or more, identical to a native or reference sequence.
  • the degree of homology (percent identity) between a native and a variant sequence can be determined, for example, by comparing the two sequences using freely available computer programs commonly employed for this purpose on the world wide web (e.g., BLASTp or BLASTn with default settings).
  • a “vector” as used herein refers to a macromolecule or association of macromolecules that comprises or associates with a polynucleotide and which can be used to mediate delivery of the polynucleotide to a cell, either in vitro or in vivo.
  • Illustrative vectors include, for example, plasmids, viral vectors, liposomes and other gene delivery vehicles.
  • the polynucleotide to be delivered may comprise a coding sequence of interest in gene therapy (such as a gene encoding a protein of therapeutic or interest), a coding sequence of interest in vaccine development (such as a polynucleotide expressing a protein, polypeptide or peptide suitable for eliciting an immune response in a mammal), and/or a selectable or detectable marker.
  • a coding sequence of interest in gene therapy such as a gene encoding a protein of therapeutic or interest
  • a coding sequence of interest in vaccine development such as a polynucleotide expressing a protein, polypeptide or peptide suitable for eliciting an immune response in a mammal
  • a selectable or detectable marker such as a polynucleotide expressing a protein, polypeptide or peptide suitable for eliciting an immune response in a mammal.
  • Mammals include, for example, humans; non-human primates, e.g., apes and monkeys; and non-primates, e.g., dogs, cats, rats, mice, cattle, horses, sheep, and goats.
  • Non-mammals include, for example, fish and birds.
  • the term "disease” or “disorder” are used interchangeably, and are used to refer to diseases or conditions wherein lack of or reduced amounts of a specific gene product, e.g., a lysosomal storage enzyme, plays a role in the disease such that a therapeutically beneficial effect can be achieved by supplementing, e.g., to at least 1% of normal levels.
  • AAV virus refers to a viral particle composed of at least one AAV capsid protein and an encapsidated polynucleotide.
  • the particle comprises a heterologous polynucleotide (i.e., a polynucleotide other than a wild-type AAV genome such as a transgene to be delivered to a mammalian cell), it is typically referred to as "rAAV".
  • An AAV “capsid protein” includes a capsid protein of a wild-type AAV, as well as modified forms of an AAV capsid protein which are structurally and or functionally capable of packaging a rAAV genome and bind to at least one specific cellular receptor which may be different than a receptor employed by wild type AAV.
  • a modified AAV capsid protein includes a chimeric AAV capsid protein such as one having amino acid sequences from two or more serotypes of AAV, e.g., a capsid protein formed from a portion of the capsid protein from AAV9 fused or linked to a portion of the capsid protein from AAV- 2, and a AAV capsid protein having a tag or other detectable non-AAV capsid peptide or protein fused or linked to the AAV capsid protein, e.g., a portion of an antibody molecule which binds a receptor other than the receptor for AAV9, such as the transferrin receptor, may be recombinantly fused to the AAV9 capsid protein.
  • a chimeric AAV capsid protein such as one having amino acid sequences from two or more serotypes of AAV, e.g., a capsid protein formed from a portion of the capsid protein from AAV9 fused or linked to a portion
  • a "pseudotyped" rAAV is an infectious virus having any combination of an AAV capsid protein and an AAV genome.
  • Capsid proteins from any AAV serotype may be employed with a rAAV genome which is derived or obtainable from a wild-type AAV genome of a different serotype or which is a chimeric genome, i.e., formed from AAV DNA from two or more different serotypes, e.g., a chimeric genome having 2 inverted terminal repeats (ITRs), each ITR from a different serotype or chimeric ITRs.
  • ITRs inverted terminal repeats
  • chimeric genomes such as those comprising ITRs from two AAV serotypes or chimeric ITRs can result in directional recombination which may further enhance the production of transcriptionally active intermolecular concatamers.
  • the 5’ and 3’ ITRs within a rAAV vector of the invention may be homologous, i.e., from the same serotype, heterologous, i.e., from different serotypes, or chimeric, i.e., an ITR which has ITR sequences from more than one AAV serotype.
  • polypeptide polypeptide
  • peptide and “protein” are used interchangeably to refer to a polymer of amino acid residues.
  • sequence refers to a nucleotide sequence of any length, which can be DNA or RNA; can be linear, circular or branched and can be either single- stranded or double stranded.
  • donor sequence refers to a nucleotide sequence that is inserted into a genome.
  • a donor sequence can be of any length, for example between 2 and 10,000 nucleotides in length (or any integer value therebetween or thereabove), preferably between about 100 and 1,000 nucleotides in length (or any integer therebetween), more preferably between about 200 and 500 nucleotides in length.
  • a "homologous, non-identical sequence” refers to a first sequence which shares a degree of sequence identity with a second sequence, but whose sequence is not identical to that of the second sequence.
  • a polynucleotide comprising the wild-type sequence of a mutant gene is homologous and non- identical to the sequence of the mutant gene.
  • the degree of homology between the two sequences is sufficient to allow homologous recombination therebetween, utilizing normal cellular mechanisms.
  • Two homologous non-identical sequences can be any length and their degree of non- homology can be as small as a single nucleotide (e.g., for correction of a genomic point mutation by targeted homologous recombination) or as large as 10 or more kilobases (e.g., for insertion of a gene at a predetermined ectopic site in a chromosome).
  • Two polynucleotides comprising the homologous non-identical sequences need not be the same length.
  • an exogenous polynucleotide i.e., donor polynucleotide
  • an exogenous polynucleotide i.e., donor polynucleotide of between 20 and 10,000 nucleotides or nucleotide pairs can be used.
  • a “disease associated gene” is one that is defective in some manner in, for example, a monogenic disease.
  • An "exogenous” molecule is a molecule that is not normally present in a cell, but can be introduced into a cell by one or more genetic, biochemical or other methods. "Normal presence in the cell” is determined with respect to the particular developmental stage and environmental conditions of the cell. Thus, for example, a molecule that is present only during embryonic development of muscle is an exogenous molecule with respect to an adult muscle cell. Similarly, a molecule induced by heat shock is an exogenous molecule with respect to a non-heat- shocked cell.
  • An exogenous molecule can comprise, for example, a functioning version of a malfunctioning endogenous molecule or a malfunctioning version of a normally-functioning endogenous molecule.
  • An exogenous molecule can be, among other things, a small molecule, such as is generated by a combinatorial chemistry process, or a macromolecule such as a protein, nucleic acid, carbohydrate, lipid, glycoprotein, lipoprotein, polysaccharide, any modified derivative of the above molecules, or any complex comprising one or more of the above molecules.
  • Nucleic acids include DNA and RNA, can be single-or double-stranded; can be linear, branched or circular; and can be of any length.
  • Nucleic acids include those capable of forming duplexes, as well as triplex-forming nucleic acids.
  • An exogenous molecule can be the same type of molecule as an endogenous molecule, e.g., an exogenous protein or nucleic acid.
  • an exogenous nucleic acid can comprise an infecting viral genome, a plasmid or episome introduced into a cell, or a chromosome that is not normally present in the cell.
  • exogenous molecules are known to those of skill in the art and include, but are not limited to, lipid-mediated transfer (e.g., liposomes, including neutral and cationic lipids), electroporation, direct injection, cell fusion, particle bombardment, calcium phosphate co-precipitation, DEAE-dextran-mediated transfer and viral vector-mediated transfer.
  • An exogenous molecule can also be the same type of molecule as an endogenous molecule but derived from a different species than the cell is derived from.
  • a human nucleic acid sequence may be introduced into a cell line originally derived from a mouse or hamster.
  • an "endogenous" molecule is one that is normally present in a particular cell at a particular developmental stage under particular environmental conditions.
  • an endogenous nucleic acid can comprise a chromosome, the genome of a mitochondrion, chloroplast or other organelle, or a naturally- occurring episomal nucleic acid.
  • Vectors for AAV vectors the genome can include deletions of sequences encoding or promoter sequences for rep, cap, or both, since the functions provided by these genes can be provided in trans. The resultant vector is referred to as being “defective” in these functions.
  • the missing functions are complemented with a packaging gene, or a plurality thereof, which together encode the necessary functions for the various missing rep and/or cap gene products.
  • the packaging genes or gene cassettes are in one embodiment not flanked by AAV ITRs and in one embodiment do not share any substantial homology with the rAAV genome.
  • the level of homology and corresponding frequency of recombination increase with increasing length of homologous sequences and with their level of shared identity.
  • the level of homology that will pose a concern in a given system can be determined theoretically and confirmed experimentally, as is known in the art. Typically, however, recombination can be substantially reduced or eliminated if the overlapping sequence is less than about a 25 nucleotide sequence if it is at least 80% identical over its entire length, or less than about a 50 nucleotide sequence if it is at least 70% identical over its entire length. Of course, even lower levels of homology further reduce the likelihood of recombination. It appears that, even without any overlapping homology, there is some residual frequency of generating replication competent AAV (RCA).
  • RCA replication competent AAV
  • the rAAV vector construct, and the complementary packaging gene constructs can be implemented in this disclosure in a number of different forms. Viral particles, plasmids, and stably transformed host cells can all be used to introduce such constructs into the packaging cell, either transiently or stably.
  • the AAV vectors and complementary packaging gene(s), if any, are provided in the form of bacterial plasmids, AAV particles, or any combination thereof.
  • either the AAV vector sequence, the packaging gene(s), or both are provided in the form of genetically altered (e.g., inheritably altered) eukaryotic cells.
  • genetically altered e.g., inheritably altered
  • a variety of different genetically altered cells can thus be used in the context of this disclosure.
  • a mammalian host cell may be used with at least one intact copy of a stably integrated rAAV vector.
  • An AAV packaging plasmid comprising at least an AAV rep gene operably linked to a promoter can be used to supply replication functions (as described in U.S. Pat. No. 5,658,776).
  • a stable mammalian cell line with an AAV rep gene operably linked to a promoter can be used to supply replication functions (see, e.g., Trempe et al., (WO 95/13392); Burstein et al. (WO 98/23018); and Johnson et al. (U.S. Pat. No.5,656,785)).
  • the AAV cap gene providing the encapsidation proteins as described above, can be provided together with an AAV rep gene or separately (see, e.g., the above-referenced applications and patents as well as Allen et al. (WO 98/27204). Other combinations are possible and included within the scope of this disclosure.
  • rAAVs e.g., rAAVs that contain capsid proteins
  • rAAVs that contain capsid proteins
  • Compositions described herein e.g., rAAVs or pharmaceutical compositions
  • In vivo gene therapy comprises administering the vectors of this disclosure directly to a subject.
  • compositions can be supplied as liquid solutions or suspensions, as emulsions, or as solid forms suitable for dissolution or suspension in liquid prior to use.
  • one exemplary mode of administration is by aerosol, using a composition that provides either a solid or liquid aerosol when used with an appropriate aerosolubilizer device.
  • Another some mode of administration into the respiratory tract is using a flexible fiberoptic bronchoscope to instill the vectors.
  • a composition described herein can be administered by any suitable route, e.g., by inhalation, nebulization, aerosolization, intranasally, intratracheally, intrabronchially, orally, parenterally (e.g., intravenously, subcutaneously, or intramuscularly), orally, nasally, rectally, topically, or buccally. They can also be administered locally or systemically.
  • a composition described herein is administered in aerosolized particles intratracheally and/or intrabronchially using an atomizer sprayer (e.g., with a MADgic® laryngo-tracheal mucosal atomization device).
  • the composition is administered parentally. In other some embodiments, the composition is administered systemically.
  • Vectors can also be introduced by way of bioprostheses, including, by way of illustration, vascular grafts (PTFE and dacron), heart valves, intravascular stents, intravascular paving as well as other non-vascular prostheses. General techniques regarding delivery, frequency, composition and dosage ranges of vector solutions are within the skill of the art.
  • the compositions described herein e.g., rAAVs or pharmaceutical compositions
  • Pressurized packs may comprise a suitable propellant such as dichlorodifluoromethane, trichlorofluoromethane, dichlorotetrafluoroethane, carbon dioxide or other suitable gas.
  • a suitable propellant such as dichlorodifluoromethane, trichlorofluoromethane, dichlorotetrafluoroethane, carbon dioxide or other suitable gas.
  • the dosage unit may be determined by providing a valve to deliver a metered amount.
  • the composition may take the form of a dry powder, for example, a powder mix of the agent and a suitable powder base such as lactose or starch.
  • the powder composition may be presented in unit dosage form in, for example, capsules or cartridges, or, e.g., gelatine or blister packs from which the powder may be administered with the aid of an inhalator, insufflator or a metered-dose inhaler.
  • the agent may be administered via nose drops, a liquid spray, such as via a plastic bottle atomizer or metered-dose inhaler.
  • atomizers are the Mistometer (Wintrop) and the Medihaler (Riker).
  • compositions described herein may be continuous or intermittent, depending, for example, upon the recipient's physiological condition, whether the purpose of the administration is therapeutic or prophylactic, and other factors known to skilled practitioners.
  • the compositions described herein can be administered once, or multiple times (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, or more times), at the same or at different sites.
  • the administration of the agents of the disclosure may be essentially continuous over a preselected period of time or may be in a series of spaced doses.
  • Exemplary rAAV Vectors Adeno-associated viruses of any serotype are suitable to prepare rAAV, since the various serotypes are functionally and structurally related, even at the genetic level.
  • AAV serotypes apparently exhibit similar replication properties mediated by homologous rep genes; and all generally bear three related capsid proteins such as those expressed in AAV2.
  • the degree of relatedness is further suggested by heteroduplex analysis which reveals extensive cross-hybridization between serotypes along the length of the genome; and the presence of analogous self-annealing segments at the termini that correspond to ITRs.
  • the similar infectivity patterns also suggest that the replication functions in each serotype are under similar regulatory control.
  • AAV2 is most commonly employed.
  • An AAV vector typically comprises a polynucleotide that is heterologous to AAV.
  • the polynucleotide is typically of interest because of a capacity to provide a function to a target cell in the context of gene therapy, such as up- or down-regulation of the expression of a certain phenotype.
  • a heterologous polynucleotide or “transgene” generally is of sufficient length to provide the desired function or encoding sequence.
  • transcription of the heterologous polynucleotide is desired in the intended target cell, it can be operably linked to its own or to a heterologous promoter, depending for example on the desired level and/or specificity of transcription within the target cell, as is known in the art.
  • Various types of promoters and enhancers are suitable for use in this context.
  • Constitutive promoters provide an ongoing level of gene transcription, and may be preferred when it is desired that the therapeutic or prophylactic polynucleotide be expressed on an ongoing basis.
  • Inducible promoters generally exhibit low activity in the absence of the inducer, and are up-regulated in the presence of the inducer. They may be preferred when expression is desired only at certain times or at certain locations, or when it is desirable to titrate the level of expression using an inducing agent. Promoters and enhancers may also be tissue-specific: that is, they exhibit their activity only in certain cell types, presumably due to gene regulatory elements found uniquely in those cells.
  • promoters are the SV40 late promoter from simian virus 40, the Baculovirus polyhedron enhancer/promoter element, Herpes Simplex Virus thymidine kinase (HSV tk), the immediate early promoter from cytomegalovirus (CMV) and various retroviral promoters including LTR elements.
  • Inducible promoters include heavy metal ion inducible promoters (such as the mouse mammary tumor virus (mMTV) promoter or various growth hormone promoters), and the promoters from T7 phage which are active in the presence of T7 RNA polymerase.
  • tissue-specific promoters include various surfactin promoters (for expression in the lung), myosin promoters (for expression in muscle), ), rhodopsin kinase (GRK1) promoters (for expression in the retina) and albumin promoters (for expression in the liver).
  • GRK1 rhodopsin kinase
  • albumin promoters for expression in the liver.
  • a large variety of other promoters are known and generally available in the art, and the sequences of many such promoters are available in sequence databases such as the GenBank database.
  • the heterologous polynucleotide will preferably also comprise control elements that facilitate translation (such as a ribosome binding site or “RBS” and a polyadenylation signal).
  • the heterologous polynucleotide generally comprises at least one coding region operatively linked to a suitable promoter, and may also comprise, for example, an operatively linked enhancer, ribosome binding site and poly-A signal.
  • the heterologous polynucleotide may comprise one encoding region, or more than one encoding regions under the control of the same or different promoters.
  • the entire unit, containing a combination of control elements and encoding region, is often referred to as an expression cassette.
  • the heterologous polynucleotide is integrated by recombinant techniques into or in place of the AAV genomic coding region (i.e., in place of the AAV rep and cap genes), but is generally flanked on either side by AAV inverted terminal repeat (ITR) regions.
  • ITR inverted terminal repeat
  • a single ITR may be sufficient to carry out the functions normally associated with configurations comprising two ITRs (see, for example, WO 94/13788), and vector constructs with only one ITR can thus be employed in conjunction with the packaging and production methods of the present invention.
  • the native promoters for rep are self-regulating, and can limit the amount of AAV particles produced.
  • the rep gene can also be operably linked to a heterologous promoter, whether rep is provided as part of the vector construct, or separately. Any heterologous promoter that is not strongly down-regulated by rep gene expression is suitable; but inducible promoters may be preferred because constitutive expression of the rep gene can have a negative impact on the host cell.
  • inducible promoters are known in the art; including, by way of illustration, heavy metal ion inducible promoters (such as metallothionein promoters); steroid hormone inducible promoters (such as the MMTV promoter or growth hormone promoters); and promoters such as those from T7 phage which are active in the presence of T7 RNA polymerase.
  • heavy metal ion inducible promoters such as metallothionein promoters
  • steroid hormone inducible promoters such as the MMTV promoter or growth hormone promoters
  • promoters such as those from T7 phage which are active in the presence of T7 RNA polymerase.
  • T7 RNA polymerase promoters
  • One sub-class of inducible promoters are those that are induced by the helper virus that is used to complement the replication and packaging of the rAAV vector.
  • helper-virus- inducible promoters include the adenovirus early gene promoter which is inducible by adenovirus E1A protein; the adenovirus major late promoter; the herpesvirus promoter which is inducible by herpesvirus proteins such as VP16 or 1CP4; as well as vaccinia or poxvirus inducible promoters.
  • Methods for identifying and testing helper-virus-inducible promoters have been described (see, e.g., WO 96/17947). Thus, methods are known in the art to determine whether or not candidate promoters are helper-virus-inducible, and whether or not they will be useful in the generation of high efficiency packaging cells.
  • one such method involves replacing the p5 promoter of the AAV rep gene with the putative helper-virus-inducible promoter (either known in the art or identified using well-known techniques such as linkage to promoter-less “reporter” genes).
  • the AAV rep-cap genes (with p5 replaced), e.g., linked to a positive selectable marker such as an antibiotic resistance gene, are then stably integrated into a suitable host cell (such as the HeLa or A549 cells exemplified below). Cells that are able to grow relatively well under selection conditions (e.g., in the presence of the antibiotic) are then tested for their ability to express the rep and cap genes upon addition of a helper virus.
  • helper-virus-inducible promoter derived from the mouse metallothionein gene has been identified as a suitable replacement for the p5 promoter, and used for producing high titers of rAAV particles (as described in WO 96/17947). Removal of one or more AAV genes is in any case desirable, to reduce the likelihood of generating replication-competent AAV (“RCA”).
  • encoding or promoter sequences for rep, cap, or both may be removed, since the functions provided by these genes can be provided in trans, e.g., in a stable line or via co-transfection.
  • the resultant vector is referred to as being “defective” in these functions.
  • the missing functions are complemented with a packaging gene, or a plurality thereof, which together encode the necessary functions for the various missing rep and/or cap gene products.
  • the packaging genes or gene cassettes are in one embodiment not flanked by AAV ITRs and in one embodiment do not share any substantial homology with the rAAV genome.
  • telomere sequences in order to minimize homologous recombination during replication between the vector sequence and separately provided packaging genes, it is desirable to avoid overlap of the two polynucleotide sequences.
  • the level of homology and corresponding frequency of recombination increase with increasing length of homologous sequences and with their level of shared identity.
  • the level of homology that will pose a concern in a given system can be determined theoretically and confirmed experimentally, as is known in the art.
  • recombination can be substantially reduced or eliminated if the overlapping sequence is less than about a 25 nucleotide sequence if it is at least 80% identical over its entire length, or less than about a 50 nucleotide sequence if it is at least 70% identical over its entire length.
  • rAAV vector construct, and the complementary packaging gene constructs can be implemented in this invention in a number of different forms. Viral particles, plasmids, and stably transformed host cells can all be used to introduce such constructs into the packaging cell, either transiently or stably.
  • the AAV vectors and complementary packaging gene(s), if any, are provided in the form of bacterial plasmids, AAV particles, or any combination thereof.
  • either the AAV vector sequence, the packaging gene(s), or both are provided in the form of genetically altered (preferably inheritably altered) eukaryotic cells.
  • the development of host cells inheritably altered to express the AAV vector sequence, AAV packaging genes, or both provides an established source of the material that is expressed at a reliable level.
  • a variety of different genetically altered cells can thus be used in the context of this invention.
  • a mammalian host cell may be used with at least one intact copy of a stably integrated rAAV vector.
  • An AAV packaging plasmid comprising at least an AAV rep gene operably linked to a promoter can be used to supply replication functions (as described in U.S. Patent 5,658,776).
  • a stable mammalian cell line with an AAV rep gene operably linked to a promoter can be used to supply replication functions (see, e.g., Trempe et al., WO 95/13392); Burstein et al. (WO 98/23018); and Johnson et al. (U.S. No. 5,656,785).
  • the AAV cap gene providing the encapsidation proteins as described above, can be provided together with an AAV rep gene or separately (see, e.g., the above-referenced applications and patents as well as Allen et al. (WO 98/27204). Other combinations are possible and included within the scope of this invention.
  • Compositions and Routes of Delivery Any route of administration may be employed so long as that route and the amount administered are prophylactically or therapeutically useful.
  • In vivo administration of the components e.g., delivered in a viral vector such as an AAV vector(s), and compositions containing them, can be accomplished by any suitable method and technique presently or prospectively known to those skilled in the art.
  • the subject polynucleotides or polypeptides can be formulated in a physiologically- or pharmaceutically-acceptable form and administered by any suitable route known in the art including, for example, oral, nasal, rectal, transdermal, vaginal, and parenteral routes of administration.
  • parenteral includes subcutaneous, intradermal, intravenous, intramuscular, intraperitoneal, subretinal, intracochlear, intrathecal, and intracisternal administration, such as by injection.
  • Administration of the compositions can be a single administration, or at continuous or distinct intervals as can be readily determined by a person skilled in the art.
  • a polynucleotide component is stably incorporated into the genome of a person of animal in need of treatment.
  • Methods for providing gene therapy are well known in the art.
  • the compositions can also be administered utilizing liposome and nano- technology, slow release capsules, implantable pumps, and biodegradable containers, and orally or intestinally administered intact plant cells expressing the therapeutic product. These delivery methods can, advantageously, provide a uniform dosage over an extended period of time. Suitable dose ranges for are generally about 10 3 to 10 15 infectious units of viral vector per microliter delivered in 1 to 3000 microliters of single injection volume.
  • viral genomes or infectious units of vector per micro liter would generally contain about 10 4 , 10 5 , 10 6 , 10 7 , 10 8 , 10 9 , 10 10 , 10 11 , 10 12 , 10 13 , 10 14 , 10 15 , 10 16 , or10 17 viral genomes or infectious units of viral vector delivered in about 10, 50, 100, 200, 500, 1000, or 2000 microliters. It should be understood that the aforementioned dosage is merely an exemplary dosage and those of skill in the art will understand that this dosage may be varied. Effective doses may be extrapolated from dose-responsive curves derived from in vitro or in vivo test systems.
  • suitable dose ranges are generally about 10 3 to 10 15 infectious units of viral vector per microliter delivered in, for example, 1, 2, 5, 10, 25, 50, 75or 100 or more milliliters, e.g.,1 to 10,000 milliliters or 0.5 to 15 milliliters, of single injection volume.
  • viral genomes or infectious units of vector per microliter would generally contain about 10 4 , 10 5 , 10 6 , 10 7 , 10 8 , 10 9 , 10 10 , 10 11 , 10 12 , 10 13 , or 10 14 viral genomes or infectious units of viral vector.
  • suitable dose ranges, generally about 10 3 to 10 15 infectious units of viral vector per microliter delivered in, for example, 1, 2, 5, 10, 25, 50, 75 or 100 or more milliliters, e.g., 1 to 10,000 milliliters or 0.5 to 15 milliliters.
  • viral genomes or infectious units of vector per microliter would generally contain about 10 4 , 10 5 , 10 6 , 10 7 , 10 8 , 10 9 , 10 10 , 10 11 , 10 12 , 10 13 , 10 14 , 10 15 , 10 16 , or 10 17 viral genomes or infectious units of viral vector, e.g., at least 1.2 x 10 11 genomes or infectious units, for instance at least 2 x 10 11 up to about 2 x 10 12 genomes or infectious units or about 1 x 10 13 to about 5 x 10 16 genomes or infectious units.
  • Administration of vectors in accordance with the present disclosure can be achieved by direct injection of the composition or by the use of infusion pumps.
  • the composition can be formulated in liquid solutions, e.g., in physiologically compatible buffers such as Hank's solution, Ringer's solution or phosphate buffer.
  • the vectors(s) may be administered by any route including parenterally.
  • the vector(s) may be administered by subretinal, intracochlear, subcutaneous, intramuscular, or intravenous injection, orally, intrathecally, or intracranially, or by sustained release, e.g., using a subcutaneous implant.
  • the vector(s) may be dissolved or dispersed in a liquid carrier vehicle.
  • the active material may be suitably admixed with an acceptable vehicle, e.g., of the vegetable oil variety such as peanut oil, cottonseed oil and the like.
  • an acceptable vehicle e.g., of the vegetable oil variety such as peanut oil, cottonseed oil and the like.
  • Other parenteral vehicles such as organic compositions using solketal, glycerol, formal, and aqueous parenteral formulations may also be used.
  • the vector(s) may comprise an aqueous solution of a water soluble pharmaceutically acceptable salt of the active acids according to the invention, desirably in a concentration of 0.01-10%, and optionally also a stabilizing agent and/or buffer substances in aqueous solution. Dosage units of the solution may advantageously be enclosed in ampules.
  • the vector(s) may be in the form of an injectable unit dose.
  • carriers or diluents usable for preparing such injectable doses include diluents such as water, ethyl alcohol, macrogol, propylene glycol, ethoxylated isostearyl alcohol, polyoxyisostearyl alcohol and polyoxyethylene sorbitan fatty acid esters, pH adjusting agents or buffers such as sodium citrate, sodium acetate and sodium phosphate, stabilizers such as sodium pyrosulfite, EDTA, thioglycolic acid and thiolactic acid, isotonic agents such as sodium chloride and glucose, local anesthetics such as procaine hydrochloride and lidocaine hydrochloride.
  • injections can be prepared by adding such carriers to the enzyme or other active, following procedures well known to those of skill in the art.
  • a thorough discussion of pharmaceutically acceptable excipients is available in REMINGTON'S PHARMACEUTICAL SCIENCES (Mack Pub. Co., N.J. 1991).
  • the pharmaceutically acceptable formulations can easily be suspended in aqueous vehicles and introduced through conventional hypodermic needles or using infusion pumps. Prior to introduction, the formulations can be sterilized, e.g., using filters.
  • the vector(s) When the vector(s) is administered in the form of a subcutaneous implant, the compound is suspended or dissolved in a slowly dispersed material known to those skilled in the art, or administered in a device which slowly releases the active material through the use of a constant driving force such as an osmotic pump. In such cases, administration over an extended period of time is possible.
  • the dosage at which the vector(s) is administered may vary within a wide range and will depend on various factors such as the severity of the disease, the age of the patient, etc., and may have to be individually adjusted.
  • Compositions described herein may be employed in combination with another medicament. The compositions can appear in conventional forms, for example, aerosols, solutions, suspensions, or topical applications, or in lyophilized form.
  • compositions include the vector(s) and a pharmaceutically acceptable excipient which can be a carrier or a diluent.
  • a pharmaceutically acceptable excipient which can be a carrier or a diluent.
  • the active agent(s) may be mixed with a carrier, or diluted by a carrier, or enclosed within a carrier.
  • the active agent when the active agent is mixed with a carrier, or when the carrier serves as a diluent, it can be solid, semi-solid, or liquid material that acts as a vehicle, excipient, or medium for the active agent.
  • suitable carriers are water, salt solutions, alcohols, polyethylene glycols, polyhydroxyethoxylated castor oil, peanut oil, olive oil, gelatin, lactose, terra alba, sucrose, dextrin, magnesium carbonate, sugar, cyclodextrin, amylose, magnesium stearate, talc, gelatin, agar, pectin, acacia, stearic acid or lower alkyl ethers of cellulose, silicic acid, fatty acids, fatty acid amines, fatty acid monoglycerides and diglycerides, pentaerythritol fatty acid esters, polyoxyethylene, hydroxymethylcellulose and polyvinylpyrrolidone.
  • the carrier or diluent can include any sustained release material known in the art, such as glyceryl monostearate or glyceryl distearate, alone or mixed with a wax.
  • the formulations can be mixed with auxiliary agents which do not deleteriously react with the vector(s).
  • Such additives can include wetting agents, emulsifying and suspending agents, salt for influencing osmotic pressure, buffers and/or coloring substances preserving agents, sweetening agents or flavoring agents.
  • the compositions can also be sterilized if desired. If a liquid carrier is used, the preparation can be in the form of a liquid such as an aqueous liquid suspension or solution.
  • Acceptable solvents or vehicles include sterilized water, Ringer's solution, or an isotonic aqueous saline solution.
  • the vector(s) may be provided as a powder suitable for reconstitution with an appropriate solution as described above. Examples of these include, but are not limited to, freeze dried, rotary dried or spray dried powders, amorphous powders, granules, precipitates, or particulates.
  • the composition can optionally contain stabilizers, pH modifiers, surfactants, bioavailability modifiers and combinations of these.
  • a unit dosage form can be in individual containers or in multi-dose containers.
  • compositions contemplated by the present disclosure may include, for example, micelles or liposomes, or some other encapsulated form, or can be administered in an extended release form to provide a prolonged storage and/or delivery effect, e.g., using biodegradable polymers, e.g., polylactide- polyglycolide.
  • biodegradable polymers e.g., polylactide- polyglycolide.
  • examples of other biodegradable polymers include poly(orthoesters) and poly(anhydrides).
  • Polymeric nanoparticles e.g., comprised of a hydrophobic core of polylactic acid (PLA) and a hydrophilic shell of methoxy-poly(ethylene glycol) (MPEG), may have improved solubility and targeting to the CNS.
  • PLA polylactic acid
  • MPEG methoxy-poly(ethylene glycol)
  • Liposomes are very simple structures consisting of one or more lipid bilayers of amphiphilic lipids, i.e., phospholipids or cholesterol. The lipophilic moiety of the bilayers is turned towards each other and creates an inner hydrophobic environment in the membrane. Liposomes are suitable drug carriers for some lipophilic drugs which can be associated with the non-polar parts of lipid bilayers if they fit in size and geometry. The size of liposomes varies from 20 nm to few ⁇ m.
  • Mixed micelles are efficient detergent structures which are composed of bile salts, phospholipids, tri, di- and monoglycerides, fatty acids, free cholesterol and fat soluble micronutrients.
  • long-chain phospholipids are known to form bilayers when dispersed in water
  • the preferred phase of short chain analogues is the spherical micellar phase.
  • a micellar solution is a thermodynamically stable system formed spontaneously in water and organic solvents.
  • the interaction between micelles and hydrophobic/lipophilic drugs leads to the formation of mixed micelles (MM), often called swollen micelles, too.
  • MM mixed micelles
  • Lipid microparticles includes lipid nano- and microspheres.
  • Microspheres are generally defined as small spherical particles made of any material which are sized from about 0.2 to 100 ⁇ m. Smaller spheres below 200 nm are usually called nanospheres.
  • Lipid microspheres are homogeneous oil/water microemulsions similar to commercially available fat emulsions, and are prepared by an intensive sonication procedure or high pressure emulsifying methods (grinding methods). The natural surfactant lecithin lowers the surface tension of the liquid, thus acting as an emulsifier to form a stable emulsion.
  • the structure and composition of lipid nanospheres is similar to those of lipid microspheres, but with a smaller diameter.
  • Polymeric nanoparticles serve as carriers for a broad variety of ingredients.
  • the active components may be either dissolved in the polymetric matrix or entrapped or adsorbed onto the particle surface.
  • Polymers suitable for the preparation of organic nanoparticles include cellulose derivatives and polyesters such as poly(lactic acid), poly(glycolic acid) and their copolymer. Due to their small size, their large surface area/volume ratio and the possibility of functionalization of the interface, polymeric nanoparticles are ideal carrier and release systems. If the particle size is below 50 nm, they are no longer recognized as particles by many biological and also synthetic barrier layers, but act similar to molecularly disperse systems.
  • the composition can be formulated to provide quick, sustained, controlled, or delayed release, or any combination thereof, of the active agent after administration to the individual by employing procedures well known in the art.
  • the enzyme is in an isotonic or hypotonic solution.
  • a lipid based delivery vehicle may be employed, e.g., a microemulsion such as that described in WO 2008/049588, the disclosure of which is incorporated by reference herein, or liposomes.
  • the preparation can contain an agent, dissolved or suspended in a liquid carrier, such as an aqueous carrier, for aerosol application.
  • the carrier can contain additives such as solubilizing agents, e.g., propylene glycol, surfactants, absorption enhancers such as lecithin (phosphatidylcholine) or cyclodextrin, or preservatives such as parabens.
  • solubilizing agents e.g., propylene glycol
  • surfactants e.g., surfactants
  • absorption enhancers such as lecithin (phosphatidylcholine) or cyclodextrin
  • preservatives such as parabens.
  • Exemplary Human Nucleotide Sequences and Encoded Proteins The viral vector sets may in one embodiment comprise sequences for a therapeutic gene.
  • the gene is intraflagellar transport 140 (IFT140), and the nucleotide sequence comprises gcagcagtgt tgacggatac gtgagaagaa aacggcgtgg tagctcggag tgtggaatcg ggcgcgaacc tgagttctga gaagtgtgga agcacgtctg aggcaagcgg aataacctgg cccccgacgctcg gagctgcacg tgcgccg atcgccttcg gctgtgcccg atcgccttcg gctcttccg gcctcggg gcgcttcggg agtcctcggg gtctcggg gtctcggg gtctcggg gccaccttc
  • the gene is usherin (USH2A), transcript variant 1, and the nucleotide sequence comprises agttccaaga gggccaccaa gcagaccacg ctctgagctt caggtaacca agtgtttgct ctgcagaata ctttacctgg gcacccaagt cttccttcca gcattcctgc tgctacagcc tatttgctga gtaaccaggg gttacagcag cgttgccagg caacgaggga cagcggtcct gtgaagagc catttgtcac actgagggga ctggttgaaa tgcaataaag aatgatacc agcagctact catgtcttcg ccattgctaa gaacg
  • the gene is ATP binding cassette subfamily A member 4 (ABCA4), and the nucleotide sequence comprises ggacacagcg tccggagcca gaggcgctct taacggcgtt tatgtccttt gctgtctgag gggcctcagc tctgaccaat ctggtcttcg tgtggtcatt agcatgggct tcgtgagaca gatacagctt ttctgga agaactggac cctgcggaaaggcaaaaga ttcgctttgt ggtggaactc gtgtggcctttttgt ggtggaactc gtgtggccttttttggtctggtttg atctggttaa ggaatgccaa cccactctac
  • the gene is centrosomal protein 290 (CEP290), and the nucleotide sequence comprises), 1 attctggcct tggcggagtt ggggatggtg tcgcctagca gccgctgccg ctttggcttg 61 ctcgggacca tttggctgga cccagagtcc gcgtggaacc gcgataggga tctgtcaggg 121 cccgcggccg ggtccagctt ggtggttgcg gtagtgagag gcctccgctg gttgccaggc 181 ttggtctaga ggtggagcac agtgaaagaa ttcaagatgc cacctaatat aaactggaatga aagt
  • the gene is ALMS1, and the nucleotide sequence comprises 1 aggcgggcgg cactgcgcct aagctgggcc acaaccgcca gtcagggctc tccccttcccc 61 ctccctccccccccctcct cctcctctgc cgcccagagc gagacaccaa catggagcccc 121 gaggatctgc catggccggg cgagctggag gaggaggagg aggaggaggaggaggaggag 181 gaggaggaag aggaggaggc tgcagcggcg gcggcggcga acgtggacga cgtagtggtc 241 gtggaggagg tggaggaaga ggcggggcgg gagtttttt
  • the AAV vectors may include any recombination site which may be employed with the corresponding recombinase, which may be provide in trans, e.g., encoded on one of the AAV vectors or expressed in a host cell.
  • Exemplary recombinases and recombination sited include but are not limited to Cre recombinase and lox sites; FLP recombinase and frt sites; Dre recombinase and rox sites; Nigri recombinase (Vibrio nigirpulchritudo) and noxP sites; Vika recombinase and vox sites; or Panto (Pantoea sp.) recombinase and pox sites.
  • the recombination sites to be employed with viral vector sets include those having mutation(s) in the core sequence, mutations in the left or right flanking sequences (the non-mutated versions are palindromic sequences), or combinations thereof.
  • a lox site has up to about 13, 14 or 15 nucleotides of a left flanking sequence, up to about 8 nucleotides of a core sequence and up to about 13, 14 or 15 nucleotides of a right flanking sequence.
  • mutations in a reference core sequence include 1, 2, 3, 4, 5, 6, 7, or 8 nucleotide substitutions, wherein the substitutions are not necessarily consecutive.
  • Mutations in a flanking sequence include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 or 13 or more nucleotide substitutions, wherein the substitutions are not necessarily consecutive.
  • a core sequence has 1, 2, 3, 4, or 5 nucleotide substitutions relative to a reference sequence.
  • a flanking sequence has 1, 2, 3, 4 or 5 nucleotide substitutions relative to a reference sequence.
  • exemplary lox sequences include but are not limited to: loxP ATAACTTCGTATA (left) (SEQ ID NO:11) GCATACAT (core) TATACGAAGTTAT (right) (SEQ ID NO:12) loxN ATAACTTCGTATA (left) (SEQ ID NO:13) GTATACCT (core) TATACGAAGTTAT (right) (SEQ ID NO:14) Lox2272 ATAACTTCGTATA (left) (SEQ ID NO:15) GGATACTT (core) TATACGAAGTTAT (right) (SEQ ID NO:16) LoxHT1 ATAACTTCGTATA (left) (SEQ ID NO:17) CTATAGCC (core) TATACGAAGTTAT (right) (SEQ ID NO:18) LoxHT2 ATAACTTCGTATA (left) (SEQ ID NO:19) TACTATAC (core) TACT
  • Exemplary products of recombination include but are not limited to: lox1517 AATTATTCGTATA (left) (SEQ ID NO:47) GCATACAT (core) TATAGCAATTTAT (right) (SEQ ID NO:48) Lox72 taccgTTCGTATA (left) (SEQ ID NO:49) GCATACAT (core) TATACGAAcggta (right) (SEQ ID NO:50)
  • An exemplary core sequence comprises: GX1ATAX2X3T, where X1 is absent or is any one of C, T, A or G; where X2 is absent or is any one of C, T, A or G; or where X3 is absent or is any one of C, T, A or G; or any combination thereof.
  • Another exemplary core sequence comprises: X1X2X3TAX4X5X6, where X1 is absent or is any one of C, T, A or G; where X2 is absent or is any one of C, T, A or G; where X3 is absent or is any one of C, T, A or G; where X4 is absent or is any one of C, T, A or G; where X5 is absent or is any one of C, T, A or G; or where X6 is absent or is any one of C, T, A or G; or any combination thereof.
  • the core sequence in at least one lox site if at least one of the rAAV has two lox sites) binds Cre and is compatible.
  • the core sequences may be incompatible, e.g., as a result of a mutation such as a nucleotide substitution and /or a deletion(s).
  • the core sequence is asymmetric. Flanking sequences are not necessarily palindromic as one of the flanking sequences in a specific lox site in a rAAV has one or more nucleotide substitutions and/or a deletion(s).
  • one of the lox sites for recombination in one of the rAAVs has a mutation(s) in one of the flanking sequences and one of the lox sites in the other rAAV of a pair for recombination has a mutation(s) in the other flanking sequence.
  • one of the lox sites for recombination in one of the rAAVs has a sequence in one of the flanking sequences that differs from the corresponding sequence in the lox site for recombination in the other rAAV.
  • An exemplary left flanking sequence comprises: X1X2X3X4X5TTCGTATA, where X1, X2, X3, X4 or X5, individually, is absent or is any one of C, T, A or G.
  • X2 and X5 are A.
  • X3 and X4 are T.
  • a left flanking sequence comprises AATTATTCGTATA (SEQ ID NO:51).
  • a left flanking sequence comprises ATAACTTCGTATA (SEQ ID NO:52).
  • An exemplary right flanking sequence comprises: TATAX1X2AAX3X4X5X6, where X1, X2, X3, X4, X5 or X6, individually, is absent or is any one of C, T, A or G.
  • X1 and X3 are G.
  • X3 and X4 are T.
  • a right flanking sequence comprises TATAGCAATTTAT (SEQ ID NO:53).
  • a right flanking sequence comprises TATACGAAGTTAT (SEQ ID NO:54). The invention will be described by the following non-limiting examples.
  • Example 1 AAV vectors are generated with specific therapeutic genes inserted (e.g., genes encoding ABCA4, USH2A, IFT140, or CEP290) useful for AAV gene therapy to prevent, inhibit or treat, for example, ABCA4-associated retinal degeneration, USH2A-associated Usher syndrome, IFT140-associated retinitis pigmentosa, or CEP290-associated Leber congenital amaurosis.
  • genes encoding ABCA4, USH2A, IFT140, or CEP290 useful for AAV gene therapy to prevent, inhibit or treat, for example, ABCA4-associated retinal degeneration, USH2A-associated Usher syndrome, IFT140-associated retinitis pigmentosa, or CEP290-associated Leber congenital amaurosis.
  • any therapeutic gene may be inserted into the described vectors, such as genes encoding MYO7A, PCDH15, CACNA1F, CDH23, or ALMS1, or other large genes that cause or are associated with genetic diseases
  • the 5’ vector which carries the first half of a cargo gene, consists of 2 AAV inverted terminal repeats (ITRs), a promoter, a cloning site to insert the first half of a cargo gene, a splice donor (SD) site (sequence: GTAAGTAACAAGGTTAAAGACAGGTTTAAGGAGACCAATAGAAACT GGGCTTGTCGAGACAGAGAACT TGCGTTTCGAGG) (SEQ ID NO:55), and a loxJT15 (or loxJTZ17) site.
  • ITRs inverted terminal repeats
  • SD splice donor
  • the 3’ vector which carries the second half of the cargo, consists of 2 ITRs, a loxJTZ17 (or loxJT15, if loxJTZ17 is used in the 5’ vector) site, a splice acceptor (SA) site (sequence: GTCTTACTGACATCCACTTTGCCTTTCTCTCCACAG) (SEQ ID NO:56), a cloning site to insert the second half of the cargo, and a transcription termination signal.
  • SA splice acceptor
  • the loxJT15:N + loxJTZ17:N or the loxJT15:22 + loxJTZ17:22, the loxJT15:HT1 + loxJTZ17:HT1, or the loxJT15:HT2 + loxJTZ17:HT2 pair may be used.
  • a CMV promoter is included in the 5’ vector for ubiquitous transgene expression, but other promoters (e.g., EF1 ⁇ , CAG, CBh, etc.) may be used depending on target cells, where the cargo gene is expressed, and desired expression levels. We synthesized minimal SD and SA sites to maximize the space available for cargo genes.
  • a BGH polyA signal was added to the 3’ vector, but it may be replaced with other polyA signals (e.g., SV40 polyA) as needed.
  • the human ABCA4 gene the coding sequence of which is ⁇ 6.8 kb, was split into two fragments and inserted into the 5’ and the 3’ AAV vectors.
  • a 3’ vector was generated with a canonical loxP site and the production of full-length ABCA4 was compared between loxJTZ17- and loxP-containing 3’ vectors. Due to the size restriction, the CRE expression cassette was provided in a separate vector.
  • the same 5’ vector used in the two-AAV set is used.
  • the 3’ vector is also very similar to the one included in the two-AAV set, but loxJTZ17:22 is used instead of loxJTZ17.
  • the middle vector consists of 2 ITRs, a loxJTZ17 site, a SA site, a cloning site to insert a part of the cargo gene, a SD site, and a loxJT15:22 site.
  • the use of non-compatible pairs prevents nonproductive recombinations (e.g., recombination between the 5’ and the 3’ vectors and the deletion of the middle vector after full assembly).
  • the coding sequences of Green Fluorescent Protein (GFP; ⁇ 0.7 kb), human Bardet-Biedl Syndrome 1 (BBS1; ⁇ 1.8 kb; with an HA- tag), and human Leucine Zipper Transcription Factor-Like 1 (LZTFL1; ⁇ 1.0 kb; with a FLAG-tag) was inserted into the 5’, middle, and 3’ vectors, respectively.
  • the AAV vectors were delivered to HEK293T cells together with a CRE vector, and the expression of GFP-BBS1-LZTFL1 fusion protein was probed by western blotting.
  • GFP-BBS1-LZTFL1 fusion proteins which were recognized by all 3 antibodies (i.e., anti-GFP, anti-HA, and anti-LZTFL1), were produced only when the 3 AAV vectors and the CRE vector were co- transduced (lane 7).
  • the migration rate of the detected protein is in good agreement with the predicted molecular mass of the full-length fusion protein ( ⁇ 130 kDa).
  • the production of GFP-BBS1-LZTFL1 fusion proteins was CRE-dependent, as they were not produced when the CRE vector was omitted (lane 8).
  • the first middle vector which carries CDS2, consists of 2 ITRs, a loxJTZ17 site, a SA site, a cloning site to insert a part of the cargo gene, a SD site, and a loxJT15:N site.
  • the second middle vector which carries CDS3, consists of 2 ITRs, a loxJTZ17:N site, a SA site, a cloning site to insert a part of the cargo gene, a SD site, and a loxJT15:22 site.
  • the coding sequences of the N-terminal half of IFT140 ( ⁇ 2.0 kb; with a HA tag), IFT57 ( ⁇ 1.3 kb; with a MYC tag), BBS5 (1.0 kb; with a HA tag), and LZTFL1 (with a FLAG tag) were inserted into the 5’, 1st middle, 2nd middle, and 3’ vectors, respectively.
  • the AAV vectors were delivered to HEK293T cells together with a CRE vector, and the expression of IFT140-IFT57- BBS5-LZTFL1 fusion protein was probed by western blotting.
  • IFT140-IFT57-BBS5-LZTFL1 fusion proteins which were recognized by all 3 antibodies (i.e., anti-HA, anti-MYC, and anti-LZTFL1), were produced only when the four AAV vectors and the CRE expression vector were co- transduced (lane 9).
  • the migration rate of the detected protein was very close to the predicted molecular mass of the full-length fusion protein ( ⁇ 200 kDa).
  • Adeno-associated virus is a proven safe gene delivery vehicle for retinal gene therapy, however, its main drawback is the limited packaging capacity.
  • the study provides an example of a generic and effective gene therapy strategy for large therapeutic genes, e.g., for retinal gene therapy. These strategies are used to develop gene therapy vectors for ABCA4- associated retinal dystrophy.
  • ABCA4 is a member of the A subfamily of ATP- binding cassette transporters and is expressed in both rod and cone photoreceptors with weaker expression in RPE cells.
  • ABCA4 localizes to the rim of the photoreceptor outer segment disc membranes and transports all-trans-retinal (covalently bound to phospholipid) from the luminal leaflet to the cytoplasmic leaflet of these membranes.
  • mutations in ABCA4 are the most common cause of Mendelian retinal diseases. In a study of 1000 consecutive families seen by a single clinician, 173 of them (17.3%) were found to have disease-causing genotypes in ABCA4. More than 30,000 people in the U.S. are currently affected with ABCA4-associated retinal diseases. Their specific clinical findings range from an extremely aggressive cone-rod dystrophy that begins in the first decade of life and can result in complete blindness by age 40, to a later onset condition limited to the macula.
  • the approaches described herein take advantage of the efficient gene delivery and the safety of the AAV vector, while overcoming its limitation on the packaging capacity, they deliver full-length therapeutic genes/proteins, and so are useful for patients with loss of function mutations.
  • Other hereditary visual impairment-causing genes that are larger than that limit of AAV include but are not limited to ABCA4, USH2A, CEP290, MYO7A, and PCDH15. Reconstitution of the ABCA4 therapeutic gene cassette at the DNA level utilizing the CRE-lox recombination system Inefficient delivery of AAV vectors (i.e., scarce co-transduction) was not the main factor that limited efficient reconstitution of dual AAV vectors.
  • the CRE-lox site-specific DNA recombination system was used to enhance the recombination efficiency of dual AAV vectors (Figure 7A).
  • the 5’ vector is composed of a CMV promoter, 5’ half of the ABCA4 coding sequence, a splice donor (SD) site, and a lox71 site.
  • the 3’ vector is composed of a lox66 site, a splice acceptor (SA) site, 3’ half of the ABCA4 coding sequence, and a polyA transcription termination signal.
  • lox71 and lox66 sites results in the forward reaction (e.g., generation of the reconstituted ABCA4 expression cassette) favored.
  • CRE recombinase is delivered via a separate AAV vector.
  • ABCA45’ and 3’ plasmids are transfected together with a CRE expression vector into HEK293T cells and the production of full-length ABCA4 proteins confirmed by immunoblotting (Figure 7B).
  • Abca4 -/- mice at two different ages (4 and 12 weeks of age) receive 1x10 9 viral particles of the AAV5-ABCA4 vectors via subretinal injection.
  • contralateral eyes are used as a control.
  • Each animal is analyzed via fluorescent ophthalmoscopy, optical coherence tomography (OCT), and electroretinography (ERG) at 4-, 10-, and 24-weeks following injection.
  • OCT optical coherence tomography
  • ERP electroretinography
  • deletion of Abca4 results in the accumulation of autofluorescent lipofuscin-like materials in the RPE, which is detectable between 16 and 40 weeks of age.
  • the level of autofluorescent lipofuscin accumulation in treated vs. contralateral control eyes is directly compared in each animal.
  • Example 3 Described herein is a novel strategy to deliver large genes using AAVs. Cargo genes are split in 2-4 AAV vectors and reconstituted by using the CRE-lox DNA recombination system.
  • novel lox sites which were generated by combining non-compatible and reaction equilibrium-modifying lox site variants, enables efficient reconstitution of a therapeutic cassette in a pre-determined configuration.
  • This approach enables the development of AAV-based, generic gene replacement therapy vectors by delivering full-length coding sequences of large disease-causing genes.
  • Development of novel lox site variants for sequence-specific, unidirectional recombination The canonical loxP site consists of two 13-bp inverted repeats (left and right elements; LE and RE, respectively) separated by an asymmetric 8-bp spacer/core sequence (Fig.7A).
  • the spacer While the left and right elements are the binding sites of the CRE recombinase, the spacer participates in the strand exchange reaction and dictates the compatibility between lox sites (i.e., whether two lox sites can recombine or not). The asymmetry of the spacer also provides the loxP site with directionality.
  • variants have mutations within the spacer sequence, and these mutations prevent strand exchange (and consequently recombination) between non-compatible lox sites while allowing recombination between homologous (or compatible) sites.
  • a high- throughput screen identified fully non-compatible and promiscuous lox sites (Missirlis et al., 2006).
  • the second group is reaction equilibrium-modifying variants ( Figure 1B). These variants have mutations in either LE or RE but not in both (e.g., loxJT15, loxJTZ17, lox71, and lox66) (Albert et al, 1995; Thomson et al., 2003).
  • the single-element mutations do not affect the binding of CRE to the lox site, and recombination between these mutant lox sites occurs as efficiently as between canonical loxP sites.
  • the recombination between LE and RE single mutants produces an LE/RE double mutant and a canonical loxP site.
  • the presence of mutations in both LE and RE significantly reduces the affinity of the LE/RE double mutant to CRE, making the double mutant a poor substrate of CRE.
  • the reaction equilibrium is drastically shifted toward the forward direction when LE and RE single mutants are used as substrates because the reverse reaction is much slower than the forward reaction.
  • loxJT15- loxJTZ17 pair was the most effective in inhibiting the reverse-direction recombination (Thomson et al., 2003).
  • loxN, lox2272, loxm7, and two additional lox sites identified by a high-throughput screen (spacer sequences: CTATAGCC (named loxHT1 herein) and TACTATAC (loxHT2) (Missirlis et al., 2006).
  • the loxN-based pair was generated by replacing the spacer sequence of loxJT15 and loxJTZ17 (GCATACAT) with that of loxN (GTATACCT).
  • hybrid lox sites should be non-compatible with one another, preventing the excision of intervening sequences and unintended recombinations (Fig. 8D and 8E). At the same time, they should significantly increase the yield of reconstituted genes by inhibiting reverse reactions, particularly when 3 or more AAV vectors are used (Fig.8F).
  • Fig.8F We first tested whether the hybrid lox sites that we developed were fully non-compatible with one another in mammalian cells. To this end, we designed GFP expression cassettes capable of tracking recombination events between different lox sites (Fig.9 and Fig.10).
  • the first reporter construct referred to as loxP-2272, is composed of a CMV promoter, a GFP coding sequence, and a loxJT15 (15:P) site followed by an in-frame 156-bp segment from the human CEP290 C-terminus (C290C; amino acids 2428-2479) and a stop codon.
  • the coding sequence of the GFP+C290C fusion protein is followed by a loxJTZ17:m7 hybrid (hereafter denoted as 17:m7 for brevity), a FLAG tag, a 17:HT1 hybrid, an HA tag, a 17:HT2 hybrid, a MYC tag, a 17:2272 hybrid, and a V5 tag.
  • Stop codons were added after each of the FLAG, HA, MYC, and V5 tags. In the absence of recombination, this reporter generates 35-kDa GFP+C290C fusion proteins, which can be detected by our CEP290 antibody (Fig.9B and Fig.10). However, when recombination takes place, the C290C fragment is excised and one of the four tags is spliced to GFP in-frame, depending on which lox site recombines with the loxJT15 (15:P) site. For instance, recombination between the 15:P and the 17:HT1 sites results in the production of GFP+HA fusion proteins ( ⁇ 30 kDa).
  • recombination events not involving the 15:P site do not lead to the fusion of associated tags with GFP and therefore go unreported.
  • We created four additional reporter constructs (loxP-N, lox2272-N, loxP- HT2, and lox2272-HT2; Fig. 9A) and examined the compatibility between the hybrid lox sites by co-transfecting these reporters with a CRE expression vector into HEK293T cells.
  • Fig.9B reporters containing lox17:N (loxP-N and lox2272-N) expressed GFP+V5 fusion proteins when CRE was present.
  • CRE-lox mediated reconstitution of large genes three-AAV vector set
  • the first vector comprises a CMV promoter, the first 1,923 bp of the IFT140 coding sequence, a splice donor (SD) site, and a loxJT15 site.
  • SD splice donor
  • loxJT15 a loxJT15 site.
  • An HA tag was added to the N-terminus of IFT140 for the detection of expressed proteins.
  • the second vector contains a loxJTZ17 site, a splice acceptor (SA) site, the coding sequence of BBS1 (1,775 bp; including linker sequences), a SD site, and a lox15:2272 site.
  • the third vector is composed of a lox17:2272 site, a SA site, the LZTFL1 coding sequence (988 bp; including a linker sequence), and a bovine growth hormone (BGH) transcription termination signal.
  • BGH bovine growth hormone
  • AAV vectors all utilizing serotype 2 were transduced individually or in various combinations to HEK293T cells. Two different doses were used: a “low” dose, where 293T cells were transduced at a multiplicity of infection (MOI) of 1.5x104 for each vector, and a “high” dose, with cells being transduced at an MOI of 6.0x104 for each vector.
  • CRE recombinase was delivered via a separate AAV vector (AAV-EF1 ⁇ -CRE) with an MOI of 0.3x104 for the low dose and 1.2x104 for the high dose.
  • CRE-lox mediated reconstitution of large genes four-AAV vector set
  • the first and last AAV vectors that contained the IFT140 and LZTFL1 coding sequences were the same ones used in the 3-AAV set above.
  • the second vector was constructed with a loxJTZ17 site, a SA site, the IFT57 coding sequence (1,330 bp; including linker sequences), a SD site, and a lox15:HT1 site.
  • the third vector was composed of a lox17:HT1 site, a SA site, the BBS5 coding sequence (1,090 bp; including linker sequences), a SD site, and a lox15:2272 site.
  • These AAV vectors were delivered to 293T cells at an MOI of 2.5x104 per vector.
  • the AAV-EF1 ⁇ -CRE vector was transduced at an MOI of 0.5x104.
  • reaction equilibrium-modifying lox sites i.e., loxJT15 and loxJTZ17
  • the 5’ vector contained a CMV promoter and a loxJT15 site, which undergoes recombination with both loxP and loxJTZ17 sites. Due to the size restriction, the CRE expression cassette was delivered via a separate AAV vector.
  • Dual AAV- ABCA4 vectors were delivered to 293T cells at an MOI of 3x10 4 (per vector) and AAV-EF1 ⁇ -CRE was transduced at an MOI of 1x10 4 .
  • full-length ABCA4 proteins ⁇ 260 kDa
  • the 3’ vector with loxJTZ17 yielded 5-10 times more ABCA4 than the one with loxP.
  • IFT140 coding sequence (4,389 bp) is small enough to be accommodated within a single AAV vector, additional regulatory sequences such as a promoter, a transcription termination signal, and two inverted terminal repeats (ITRs) must be included in the gene therapy vector, and the addition of such sequences makes the IFT140 expression cassette to exceed the AAV’s packaging capacity. Therefore, at least two AAV vectors are required to deliver the IFT140 gene.
  • ITRs inverted terminal repeats
  • gp41 split inteins are one of the most efficient in facilitating protein trans-splicing (our unpublished data).
  • IFT140 is relatively small for dual AAV vectors, there is space to include the CRE gene within the IFT140 vectors.
  • CRE coding sequence along with an N-terminal T2A “self-cleaving” peptide, into the 5’ vector.
  • a BGH polyA signal was also added following the CRE gene.
  • the 5’ vector of the second set (Fig.14B) consists of a CMV (or CBh) promoter, the initial 2,301 bp of the IFT140 coding sequence, the N-terminal gp41 split intein (IntN), and a BGH transcription termination signal.
  • the 3’ vector within this set contains the same CMV promoter, the C-terminal gp41 split intein (IntC), the rest of the IFT140 coding sequence (2,088 bp), and a BGH transcription termination signal.
  • an HA tag was introduced at the N-terminus of IFT140 in both sets.
  • an IFT140 antibody 140-C Ab
  • both sets of IFT140 dual AAV vectors demonstrated efficient production of full-length IFT140 proteins (lanes 2 and 5 in Figure 7C; black arrowheads).
  • cells transduced with the protein trans-splicing set exhibited significant levels of unconjugated “half” proteins (lane 5; asterisks).
  • a plasmid DNA encoding full-length IFT140 with an N-terminal HA tag was transfected and included (lane 6).
  • CRE/lox-based dual AAV-IFT140 vectors can produce full-length IFT140 proteins in mouse retinas.
  • wild-type mouse eyes were subretinally administered with two CRE/lox sets of dual AAV-IFT140 vectors: one with a CMV promoter and the other with a CBh promoter. Both sets of AAV vectors were prepared with the AAV5 serotype and injected at the dose of 5x10 9 vg per vector.
  • the full-length human PCDH15 CDS spans 5,865 bp, necessitating two AAV vectors for delivery.
  • the CRE gene ⁇ 1.65 kb; with an internal ribosome entry site (IRES) for translation
  • IRS internal ribosome entry site
  • the CRE gene becomes “self-inactivated” as recombination progresses and becomes separated from its promoter.
  • PCDH15 is a single-pass transmembrane protein, with its N-terminal two-thirds situated on the extracellular side of the plasma membrane and the remainder on the cytoplasmic side. While a signal peptide is present at the N-terminus of PCDH15 (and PCDH15_N) for extracellular translocation, it is absent in the C- terminal half. To facilitate the extracellular translocation of IntC (and ensure the presence of IntN and IntC in the same cellular compartments), we introduced the signal peptide of PCDH15 (N-terminal 26 residues) to IntC (Fig.16B).
  • the CRE/lox-based dual AAV-PCDH15 vectors When transduced to 293T cells, the CRE/lox-based dual AAV-PCDH15 vectors robustly produced full-length PCDH15 (Fig. 16C, lane 9). In contrast, although the split-intein-based AAV-PCDH15 vectors efficiently produced the expected individual truncated proteins (lanes 1, 2, 4, and 5), the reconstituted full- length proteins were barely detectable or undetectable (lanes 3 and 6). These data indicate that the CRE/lox method is a more suitable approach for PCDH15. We then applied the CRE-lox-mediated DNA recombination approach to CDH23 gene therapy vectors.
  • CDH23 Inactivating mutations of CDH23 cause Usher syndrome type 1D (USH1D), which is characterized by profound congenital hearing impairment and progressive vision loss (Bolz et al, 2001; Di Palma et al, 2001).
  • the full-length human CDH23 CDS is 10,065 bp long, requiring three AAV vectors.
  • the loxJT15 and loxJTZ17 pair was used to join the 5’ and the middle vectors and the lox15:2272 and lox17:2272 pair was used for the middle and the 3’ vectors.
  • CDH23 is a type-I single transmembrane protein with an N-terminal signal peptide
  • an HA tag was inserted after the signal peptide for protein detection.
  • a CBh promoter and a BGH polyA signal were used as a promoter and a transcription termination signal, respectively.
  • a plasmid containing a full-length CDH23 expression cassette was used as a positive control (lane 5), and ⁇ -actin was used as a loading control.
  • the CRE-lox-mediated recombination significantly improves the recombination efficiency and the yield of correctly reconstituted genes. This is especially true when triple or quadruple AAV vectors are used.
  • the use of non- compatible, hybrid lox sites prevents the excision of floxed sequences, ensures recombination in a pre-determined configuration, and inhibits the disassembly of reconstituted genes (Figs.8D-8F).
  • the CRE-lox-mediated DNA recombination approach provides more flexibility regarding splitting positions compared to the protein trans- splicing approach.
  • the efficiency of protein trans-splicing is influenced by the amino acid residues adjacent to split inteins (Chong et al, 1998; Iwai et al., 2006; Shah et al., 2013).
  • the first residue within the C-extein is particularly important, and Cys, Ser, and Thr residues are strongly preferred. This constraint greatly limits the number of possible locations where a protein may be split.
  • protein truncations can affect a protein’s structure, stability, and localization, and these factors also influence the overall efficiency and yield of the protein reconstitution.
  • the target gene encodes a transmembrane or secreted protein
  • the topology and secretion of each protein fragment should be considered when determining splitting positions. Finding splitting positions for protein trans-splicing ideally requires identifying sites where neither the process of trans-splicing is inhibited, nor the folding and stability of each protein fragment is affected by truncation, while the size of each fragment should be small enough to fit into single AAV vectors. Additionally, it is desirable that the truncated proteins localize to the same compartment or close locations to increase the likelihood of engagement.
  • Identifying optimal splitting positions is challenging and usually involves comparing multiple candidate sites empirically. And the complexity increases if the target gene requires 3 or 4 AAV vectors.
  • protein structure, stability, localization, and topology are not factors to consider since the reconstitution happens at the DNA level.
  • Cargo capacity expansion can be achieved by merely adding additional sets of non-compatible lox sites to AAV vectors.
  • Another significant advantage of the CRE-lox approach over protein trans- splicing is the lack or minimal production of truncated proteins. Protein trans- splicing requires the production of “half” proteins before reconstitution, which can have dominant negative or harmful effects if continuously expressed.
  • truncated protein production is either absent or low when the CRE-lox strategy is used because the AAV vectors lack a polyA signal, which stabilizes mRNA, or a promoter. Although ITRs have some intrinsic promoter activities, they are very weak in most cells.
  • the CRE gene is included in the 5’ vector, a truncated protein and CRE are initially produced. However, the vector is converted to a full- length therapeutic cassette and the production of truncated proteins and CRE diminishes as recombination progresses.
  • the lack or minimal production of truncated proteins may be crucial for certain genes if such protein products are toxic to cells, and the “self-inactivation” feature of the CRE-containing 5’ vector provides an additional layer of safety to the CRE-lox approach.
  • the CRE-lox approach requires the delivery of CRE in addition to therapeutic genes, the practical payload capacity of AAV vectors with the CRE-lox approach is either comparable with or larger than that of the split intein-based approach.
  • the protein trans-splicing approach requires each AAV vector to have its own promoter and transcription termination signal to produce therapeutic gene products and split inteins. The repeated inclusion of transcriptional regulatory elements erodes the AAV vector’s combined payload capacity.
  • the CRE-lox approach only requires one promoter and one transcriptional termination signal for the entire therapeutic gene, which becomes more beneficial as more AAV vectors are needed.
  • One notable concern of the CRE-lox approach is the prolonged expression of CRE in transduced cells. Prolonged expression of CRE could lead to unintended recombination events in the human genome, potentially resulting in unwanted mutations or genomic instability. Moreover, prolonged CRE expression could also lead to immune responses, which may limit the effectiveness of AAV gene therapies. This could potentially result in the destruction of cells expressing the AAV vectors or a reduction in the efficacy of the AAV gene therapy over time. In this regard, the inclusion of CRE in 5’ vectors and being “self-inactivated” by recombination significantly reduces this risk.
  • an inducible promoter or destabilization domain-fused CRE recombinase may be used.
  • constitutive expression of CRE doesn’t appear to cause serious health concerns in rodents.
  • the CRE-lox approach offers a simple, versatile, and efficient platform for producing AAV gene therapy vectors capable of delivering large genes. As this approach delivers full-length genes, the gene therapy vectors developed using this approach have the potential to be generally applicable to all patients with loss-of-function mutations.
  • a set of AAV vectors comprising: a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; and a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right
  • a set of AAV vectors comprising: a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third lox site comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; and a third AAV vector having a genome comprising an ITR linked to a fourth lox site comprising a fourth left flanking sequence linked to a fourth core sequence
  • a set of AAV vectors comprising: a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third lox site comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; a third AAV vector having a genome comprising an ITR linked to a fourth lox site comprising a fourthleft flanking sequence linked to a fourth core sequence linked
  • the set of statements 1, 2 or 3 further comprising a vector encoding Cre. 5.
  • the host cell of statements 10, 11 or 12 which expresses Cre. 14.
  • the host cell of statements 10, 11, 12 or 13 which is infected with a virus that encodes Cre.
  • the host cell of any one of statements 10 to 14 wherein the host cell is infected with a composition comprising all of the vectors.
  • the host cell of any one of statements 10 to 15 which is a mammalian host cell. 17.
  • a method to express a gene in a mammalian cell comprising infecting the cell with a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; and a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flank
  • a method to express a gene in a mammal comprising administering to the mammal an effective amount of a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR and a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the
  • the method of statement 18 wherein the mammal is a human.
  • 20. The method of statements 18 or 19 wherein the vectors are systemically administered.
  • 21. The method of statements 18 or 19 wherein the vectors are locally administered.
  • 22. The method of any one of statements 18 to 21 wherein the vectors are injected.
  • 23. The method of any one of statements 18 to 22 wherein the gene is a therapeutic gene.
  • 24. The method of any one of statements 18 to 22 wherein the gene is a prophylactic gene.
  • 25. The method of any one of statements 18 to 23 wherein the mammal has ABCA4-associated retinal degeneration, USH2A-associated Usher syndrome, IFT140-associated retinitis pigmentosa, or CEP290-associated Leber congenital amaurosis.

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Abstract

The disclosure provides a method to assemble up to four viral, e.g., adeno- associated virus (AAV), genomes in vivo in a pre-designed configuration using a DNA recombination system to provide delivery of large genes that exceed the AAV' s packaging capacity. Split into up to four AAV vectors, the disclosed CRE- lox site-specific DNA recombination system may be used for (but not limited to) gene therapies requiring large gene delivery.

Description

METHOD TO DELIVER LARGE GENES USING VIRUS AND A DNA RECOMBINATION SYSTEM Cross-reference to Related Application This application claims the priority of U.S. provisional application Serial No. 63/419,541, filed October 26, 2022, the disclosure of which is incorporated herein by reference in its entirety. Incorporation by Reference of Sequence Listing A Sequence Listing is provided herewith as an xml file named “875236WO1.xml” created on October 26 , 2023 and having a size of 98,451 bytes. The content of the xml file is incorporated by reference herein in its entirety. Background Previously described methods to deliver large genes using AAV as a vehicle include hybrid dual (or triple) AAV, split intein-mediated protein trans- splicing, and lox66/71-CRE mediated recombination approaches (Trapani et al., 2020; Ghosh et al., 2008; Maddalena et al., 2018; Villiger et al., 2018; Tornabene et al., 2019; Barrett et al., 2021). These approaches have notable limitations in their use. Specifically, the hybrid dual (or triple) AAV approach, which utilizes recombinogenic sequences to improve recombination efficiency, still exhibits very low recombination efficiencies. The efficiency and use of the split intein- mediated protein trans-splicing approach is affected by several factors: 1) amino acid residues at the splitting position (protein trans-splicing efficiency varies depending on the amino acid residues adjacent to split inteins), 2) stability and structure of the expressed N- and C-terminal protein fragments (the effect of truncation on protein stability and structure is hard to predict), and 3) subcellular localization of the expressed N- and C-terminal protein fragments (proximity of the protein fragments is required for protein trans-splicing, but co-localization of the N- and the C-terminal fragments may not occur). Summary The disclosure provides a method to assemble up to four viral, e.g., adeno- associated virus (AAV), genomes in vivo in a pre-designed configuration using a DNA recombination system, e.g., the CRE-lox site-specific DNA recombination system. AAV is a safe and efficient gene delivery vehicle for gene therapies, but its packaging capacity is limited to 4.8 kb. This limited packaging capacity precludes its use as a vehicle to deliver large genes. The CRE-lox DNA recombination system, as an example, is a highly efficient method to recombine DNA molecules. In the present disclosure, mutant loxP sequences were designed and others selected and used to provide a series of AAV vectors that enable the assembly of multiple AAV vectors in a pre-designed configuration using the CRE recombinase. This method enables the delivery of large genes that exceed the AAV’s packaging capacity, split into up to four AAV vectors, and may be used for (but not limited to) gene therapies requiring large gene delivery. Exemplary genes for delivery to various organs include but are not limited to genes encoding ABCA4, CEP290, USH2A, MYO7A, PCDH15, CACNA1F, CDH23, OTOF, DYSF, ALMS1, DMD and the like. The method is superior to the other approaches because 1) it improves the recombination efficiency, 2) there is very little restriction in terms of selecting split sites, 3) protein fragment structure, stability, and localization are not issues because the reconstitution occurs at the DNA level, and 4) multiple AAV vectors can be assembled in a predetermined configuration. Therefore, the present methods and vectors provide a highly efficient and flexible method to deliver large genes using AAV vectors. In one embodiment, the disclosure provides for a set of AAV vectors comprising a first AAV vector having a genome comprising an inverted terminal repeat (ITR) linked to, in one embodiment, a heterologous promoter, linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site, linked to a first recombination site, e.g., a lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; and a second AAV vector having a genome comprising an ITR linked to a second recombination site, e.g., a lox site, comprising a second left flanking sequence, linked to a second core sequence linked to a second right flanking sequence, linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence. In one embodiment, the disclosure provides a set of AAV vectors comprising a first AAV vector having a genome comprising an ITR linked to, in one embodiment, a heterologous promoter, linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first recombination site, e.g., a lox site, comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second recombination site, e.g., a lox site, comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third recombination site, e.g., a lox site, comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; and a third AAV vector having a genome comprising an ITR linked to a fourth recombination site, e.g., a lox site, comprising a fourth left flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence or the fourth core sequence, wherein the third core sequence and the fourth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence. Further provided is a set of AAV vectors comprising a first AAV vector having a genome comprising an ITR linked to, in one embodiment, a heterologous promoter, linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first recombination site, e.g., a lox site, comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second recombination site, e.g., a lox site, comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third recombination site, e.g., a lox site, comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; a third AAV vector having a genome comprising an ITR linked to a fourth recombination site, e.g., a lox site, comprising a fourth left flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a splice donor site linked to a fifth recombination site, e.g., a lox site, comprising a fifth left flanking sequence linked to a fifth core sequence linked to a fifth right flanking sequence linked to an ITR; a fourth AAV vector having a genome comprising an ITR linked to a sixth recombination site, e.g., a lox site, comprising a sixth left flanking sequence linked to a sixth core sequence linked to a sixth right flanking sequence linked to a splice acceptor linked to a fourth portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence, the fourth core sequence, the fifth core sequence and the sixth core sequence, wherein the third core sequence and the fourth core sequence are compatible, but are not compatible with the fifth core sequence and the sixth core sequence, wherein the fifth core sequence and the sixth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have a mutation or the first right flanking sequence and the second left flanking sequence have a mutation, wherein the third left flanking sequence and the fourth right flanking sequence have a mutation or the third right flanking sequence and the third left flanking sequence have a mutation, wherein the fifth left flanking sequence and the sixth right flanking sequence have a mutation or the fifth right flanking sequence and the sixth left flanking sequence have a mutation. In one embodiment, the set further comprises a vector encoding Cre. In one embodiment, one of the vectors in the set encodes Cre. In one embodiment, the gene encodes ABCA4, USH2A, IFT140, CEP290, MYO7A, PCDH15, CACNA1F, CDH23, or ALMS1, or a variant thereof. In one embodiment, each vector in the set is the same serotype. In one embodiment, each ITR in the set is from the same serotype. Further provided is a host cell infected with a first AAV vector having a genome comprising an ITR linked to, in one embodiment, a heterologous promoter, linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first recombination site, e.g., a lox site, comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; and a second AAV vector having a genome comprising an ITR linked to a second recombination site, e.g., a lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence. Also provided is a host cell infected with a first AAV vector having a genome comprising an ITR linked to, in one embodiment, a heterologous promoter, linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first recombination site, e.g., a lox site, comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second recombination site, e.g., a lox site, comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third recombination site, e.g., a lox site, comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; and a third AAV vector having a genome comprising an ITR linked to a fourth recombination site, e.g., a lox site, comprising a fourth left flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence or the fourth core sequence, wherein the third core sequence and the fourth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence. In one embodiment, a host cell is provided that is infected with a first AAV vector having a genome comprising an ITR linked to, in one embodiment, a heterologous promoter, linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first recombination site, e.g., a lox site, comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second recombination site, e.g., a lox site, comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third recombination site, e.g., a lox site comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; a third AAV vector having a genome comprising an ITR linked to a fourth recombination site, e.g., a lox site, comprising a fourth left flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a splice donor site linked to a fifth recombination site, e.g., a lox site, comprising a fifth left flanking sequence linked to a fifth core sequence linked to a fifth right flanking sequence linked to an ITR; a fourth AAV vector having a genome comprising an ITR linked to a sixth recombination site, e.g., a lox site, comprising a sixth left flanking sequence linked to a sixth core sequence linked to a sixth right flanking sequence linked to a splice acceptor linked to a fourth portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence, the fourth core sequence, the fifth core sequence and the sixth core sequence, wherein the third core sequence and the fourth core sequence are compatible, but are not compatible with the fifth core sequence and the sixth core sequence, wherein the fifth core sequence and the sixth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have a mutation or the first right flanking sequence and the second left flanking sequence have a mutation, wherein the third left flanking sequence and the fourth right flanking sequence have a mutation or the third right flanking sequence and the third left flanking sequence have a mutation, wherein the fifth left flanking sequence and the sixth right flanking sequence have a mutation or the fifth right flanking sequence and the sixth left flanking sequence have a mutation. In one embodiment, the host cell expresses a recombinase, e.g., Cre recombinase. In one embodiment, the host cell is infected with a virus that encodes a recombinase, e.g., Cre recombinase. In one embodiment, the host cell is infected with a composition comprising all of the vectors. In one embodiment, the host cell is a mammalian host cell, e.g., HEK293, HT1080, A549, PER.C6, NIH3T3, PG13, CHO, or HepG2 cells. Further provided is a method to express a gene in a mammalian cell, comprising infecting the cell with a first AAV vector having a genome comprising an ITR linked to, in one embodiment, a heterologous promoter, linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first recombination site, e.g., a lox site, comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; and a second AAV vector having a genome comprising an ITR linked to a second recombination site, e.g., a lox site, comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence; or a first AAV vector having a genome comprising an ITR linked to, in one embodiment, a heterologous promoter, linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first recombination site, e.g., a lox site, comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second recombination site, e.g., a lox site, comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third recombination site, e.g., a lox site, comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; and a third AAV vector having a genome comprising an ITR linked to a fourth recombination site, e.g., a lox site, comprising a fourth left flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence or the fourth core sequence, wherein the third core sequence and the fourth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence, or a first AAV vector having a genome comprising an ITR linked to, in one embodiment, a heterologous promoter, linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first recombination site, e.g., a lox site, comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second recombination site, e.g., a lox site, comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third recombination site, e.g., a lox site, comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; a third AAV vector having a genome comprising an ITR linked to a fourth recombination site, e.g., a lox site, comprising a fourth left flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a splice donor site linked to a fifth recombination site, e.g., a lox site, comprising a fifth left flanking sequence linked to a fifth core sequence linked to a fifth right flanking sequence linked to an ITR; a fourth AAV vector having a genome comprising an ITR linked to a sixth recombination site, e.g., a lox site, comprising a sixth left flanking sequence linked to a sixth core sequence linked to a sixth right flanking sequence linked to a splice acceptor linked to a fourth portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence, the fourth core sequence, the fifth core sequence and the sixth core sequence, wherein the third core sequence and the fourth core sequence are compatible, but are not compatible with the fifth core sequence and the sixth core sequence, wherein the fifth core sequence and the sixth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have a mutation or the first right flanking sequence and the second left flanking sequence have a mutation, wherein the third left flanking sequence and the fourth right flanking sequence have a mutation or the third right flanking sequence and the third left flanking sequence have a mutation, wherein the fifth left flanking sequence and the sixth right flanking sequence have a mutation or the fifth right flanking sequence and the sixth left flanking sequence have a mutation. A method to express a gene in a mammal is provided, comprising administering to the mammal an effective amount of: a first AAV vector having a genome comprising an ITR linked to, in one embodiment, a heterologous promoter, linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first recombination site, e.g., a lox site, comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; and a second AAV vector having a genome comprising an ITR linked to a second recombination site, e.g., a lox site, comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence; or a first AAV vector having a genome comprising an ITR linked to, in one embodiment, a heterologous promoter, linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first recombination site, e.g., a lox site, comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second recombination site, e.g., a lox site, comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third recombination site, e.g., a lox site, comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; and a third AAV vector having a genome comprising an ITR linked to a fourth recombination site, e.g., a lox site, comprising a fourth left flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence or the fourth core sequence, wherein the third core sequence and the fourth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence; or a first AAV vector having a genome comprising an ITR linked to, in one embodiment, a heterologous promoter, linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first recombination site, e.g., a lox site, comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second recombination site, e.g., a lox site, comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third recombination site, e.g., a lox site, comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; a third AAV vector having a genome comprising an ITR linked to a fourth recombination site, e.g., a lox site, comprising a fourth left flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a splice donor site linked to a fifth recombination site, e.g., a lox site, comprising a fifth left flanking sequence linked to a fifth core sequence linked to a fifth right flanking sequence linked to an ITR; a fourth AAV vector having a genome comprising an ITR linked to a sixth recombination site, e.g., a lox site, comprising a sixth left flanking sequence linked to a sixth core sequence linked to a sixth right flanking sequence linked to a splice acceptor linked to a fourth portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence, the fourth core sequence, the fifth core sequence and the sixth core sequence, wherein the third core sequence and the fourth core sequence are compatible, but are not compatible with the fifth core sequence and the sixth core sequence, wherein the fifth core sequence and the sixth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have a mutation or the first right flanking sequence and the second left flanking sequence have a mutation, wherein the third left flanking sequence and the fourth right flanking sequence have a mutation or the third right flanking sequence and the third left flanking sequence have a mutation, wherein the fifth left flanking sequence and the sixth right flanking sequence have a mutation or the fifth right flanking sequence and the sixth left flanking sequence have a mutation. In one embodiment, the mammal is a human. In one embodiment, the vectors are systemically administered. In one embodiment, the vectors are locally administered. In one embodiment, the vectors are injected. In one embodiment, the gene is a therapeutic gene. In one embodiment, the gene is a prophylactic gene. In one embodiment, the mammal has ABCA4-associated retinal degeneration, USH2A-associated Usher syndrome, IFT140-associated retinitis pigmentosa, or CEP290-associated Leber congenital amaurosis. In one embodiment, the amount administered prevents, inhibits or treats one or more symptoms of a disease. In one embodiment, a composition comprises the vectors that are administered. Brief Description of Figures Figs.1A-1B. Two classes of lox site variants that control CRE-dependent DNA recombination. Fig. 1A shows non-compatible mutant variants (loxN and lox2272, loxHT1, and loxHT2) of loxP. Mutations in the core element (red) prevent recombination between non-compatible lox sites. Left and right elements are palindromic. Fig.1B shows reaction equilibrium-modifying variants (loxJT15 and loxJTZ17) of loxP. These variants have mutations (underlined) in either left or right elements (but not in both) and are recognized by CRE recombinase. Recombination between LE and RE mutants produces an LE/RE double mutant and a loxP sequence. LE/RE double mutants are poor substrates of CRE, and consequently the reverse reaction is significantly slower than the forward reaction. Figs. 2A-2D. Four pairs of new loxP variants that enable sequence- specific, unidirectional recombination. Fig.2A shows the loxN-based pair. The core sequence of loxJT15 and loxJTZ17, which is from loxP, is replaced with that of loxN. Fig.2B shows the lox2272-based pair. The core sequence of loxJT15 and loxJTZ17 is replaced with that of lox2272. Fig.2C shows the loxHT1-based pair. The core sequence of loxJT15 and loxJTZ17 is replaced with that of loxHT1. Fig. 2D shows the loxHT2-based pair. The core sequence of loxJT15 and loxJTZ17 is replaced with that of loxHT2. Figs. 3A-3B. CRE-lox mediated reconstitution of large genes: two-AAV set. Fig. 3A is a schematic representation of large gene reconstitution by CRE- lox mediated recombination of two AAV vectors. A gene-of-interest is split in 2 fragments (CDS1 and CDS2) and delivered to target cells via 2 separate AAV vectors. Reconstitution of the gene is achieved by CRE-lox mediated recombination of the two AAV vectors. CRE may be delivered via a separate AAV vector or included in one of the two AAV vectors if space allows. CDS1 and 2: coding sequence 1 and 2, EF1α: human elongation factor-1α promoter, ITR: inverted terminal repeat, pA: transcription termination signal, SD: splice donor, SA: splice acceptor. Fig. 3B shows successful reconstitution and expression of a large gene (ABCA4) by CRE-lox mediated recombination of two AAV vectors. The coding sequence of human ABCA4 is split and delivered to HEK293T cells via two AAV vectors, and the production of full-length ABCA4 protein was confirmed by Western blotting (WB). The ABCA4-N antibody detects the N-terminal half of ABCA4, and the ABCA4-C antibody detects the C-terminal half of ABCA4. Numbers on the right mark the location of protein standards. Lane 1: ABCA4-N only, lane 2: ABCA4-C (with loxJTZ17) only, lane 3: ABCA4-C (with loxP) only, lane 4: ABCA4-N and -C (with loxJTZ17), lane 5: ABCA4-N and -C (with loxP), lane 6: ABCA4-N and -C (with loxJTZ17), lane 7: ABCA4- N and -C (with loxP), lane 8: expression plasmids encoding full-length ABCA4 transfected. In lanes 6-8, the CRE expression vector was omitted. Figs.4A-4B. CRE-lox mediated reconstitution of large genes: three-AAV set. Fig. 4A is a schematic representation of large gene reconstitution by CRE- lox mediated recombination of three AAV vectors. A gene-of-interest is split in 3 fragments (CDS1, 2, and 3) and delivered to target cells via 3 separate AAV vectors. Others are the same as in Figure 3. Fig. 4B shows successful reconstitution of a large gene by CRE-lox mediated recombination of three AAV vectors. The coding sequences of GFP, BBS1 (with a HA tag), and LZTFL1 (with a FLAG tag) were used as CDS1, 2, and 3, respectively, and delivered to HEK293T cells to produce GFP-BBS1-LZTFL1 fusion proteins. Cell lysates were subjected to SDS-PAGE followed by Western blotting (WB) using GFP, HA (for BBS1), and LZTFL1 antibodies. Numbers on the right mark the location of protein standards. Lane 1: CDS1 (GFP) only, lane 2: CDS2 (HA-BBS1) only, lane 3: CDS3 (FLAG-LZTFL1) only, lane 4: CDS1 + CDS2, lane 5: CDS1 + CDS3, lane 6: CDS2 + CDS3, lane 7: CDS1 + CDS2 + CDS3, lane 8: CDS1 + CDS2 + CDS3 (without CRE). In lanes 1-7, a CRE expression vector was co-transduced with the indicated vectors. Endogenous LZTFL1 (red arrowhead) was used as a loading control. Figs.5A-5B. CRE-lox mediated reconstitution of large genes: four-AAV set. Fig. 5A is a schematic representation of large gene reconstitution by CRE- lox mediated recombination of four AAV vectors. A gene-of-interest is split in 4 fragments (CDS1, 2, 3, and 4) and delivered to target cells via 4 separate AAV vectors. Others are the same as in Figure 3. Fig. 5B shows successful reconstitution of a large gene by CRE-lox mediated recombination of four AAV vectors. The coding sequences of the N-terminal half of IFT140 (with a HA tag), IFT57 (with a MYC tag), BBS5 (with a HA tag), and LZTFL1 (with a FLAG tag) were used as CDS1, 2, 3, and 4, respectively, and delivered to HEK293T cells as described at the top. Cell lysates were collected 72 hours post-transduction and subjected to SDS-PAGE and western blotting (WB). The production of IFT140- IFT57-BBS5-LZTFL1 fusion proteins was examined by using HA (for IFT140 and BBS5), MYC (for IFT57), and LZTFL1 antibodies. Numbers on the right mark the location of protein standards. In lanes 1-9, a CRE expression vector was co-transduced with the indicated vectors. Endogenous LZTFL1 (red arrowhead) was used as a loading control. Fig.6. Deletion of DNA fragments encompassed by 2 compatible lox sites. The presence of 2 (or more) compatible lox sites causes rapid deletion of the intervening sequence by CRE-mediated recombination. The reverse reaction is much slower because it is a two-molecule recombination. The use of non- compatible lox sites prevents the deletion. Figs.7A-7C. Lox site variants that enable CRE-dependent recombination of multiple AAV vectors. Fig. 7A Non-compatible mutant variants of loxP. Sequence differences in the spacer region (red) prevent recombination between non-compatible lox sites. Left and right elements (LE and RE, respectively) are palindromic. Fig.7B Reaction equilibrium-modifying variants of loxP. LoxJT15 and loxJTZ17 sites have mutations (underlined) in either LE or RE but not in both. While recombination between loxP sites is fully reversible, one between loxJT15 and loxJTZ17 produces an LE/RE double mutant (lox15/17) and a loxP sequence. LE/RE double mutants are poor substrates of CRE, and consequently the reverse reaction is significantly slower than the forward reaction. Fig.7C Lox site variants that prevent recombination between non-compatible lox sites and inhibit reverse reactions. The spacer sequences of loxJT15 and loxJTZ17, which are from loxP, are replaced with those of the non-compatible lox sites (loxN, lox2272, loxm7 (not shown), loxHT1, and loxHT2). Figs. 8A-8F shows advantages of the non-compatible, reaction- equilibrium modifying lox sites. Figs. 8A-8C illustrate problems of using only one species of or compatible lox sites to assemble more than two DNA fragments. Fig. 8A: The presence of multiple compatible lox sites within a single DNA fragment leads to a rapid excision of intervening sequences. Fig. 8B: Since all DNA fragments possess compatible lox sites, recombination reactions can occur in various combinations. Fig. 8C: Because both the substrates and the products have compatible lox sites, the recombination reaction becomes fully reversible, causing the reconstituted DNAs to continuously cycle through assembly- disassembly (50:50 at the equilibrium). Figs.8D-8F: We have devised 3 pairs of novel lox sites by combining non-compatible (lox2272, loxHT1, and loxHT2; (Lee & Saito, 1998; Missirlis et al, 2006; Siegel et al, 2001)) and reaction- equilibrium modifying lox sites (loxJT15 and loxJTZ17; (Thomson et al, 2003)). Non-compatible lox sites do not undergo recombination with each other due to differences in their core sequences. Reaction-equilibrium modifying lox sites suppress reverse reactions due to the presence of mutations in one of the two CRE binding sites (Fig.8F). The hybrid lox sites that we devised are non-compatible with each other and, at the same time, prevent reverse reactions. These lox sites enable the assembly of more than two DNA fragments in a predetermined configuration. Fig.8D: Non-compatible lox sites (e.g., loxP and lox2272) prevent the excision of intervening sequences. Fig.8E: By employing two or more non- compatible lox sites, one can precisely specify the DNA fragments to recombine. Fig.8F: Incorporating reaction-equilibrium modifying lox sites (e.g., loxJT15 and loxJTZ17) enhances the yield of reconstituted DNAs by preventing the disassembly of the reconstituted cassettes (reverse reactions). Figs.9A-B Assessment of compatibility among hybrid lox sites. Fig.9A Schematics of reporter constructs to detect recombination events between loxJT15 (15:P), loxJTZ17:m7 (17:m7), loxJTZ17:HT1 (17:HT1), loxJTZ17:HT2 (17:HT2), loxJTZ17:2272 (17:2272), and loxJTZ17:N (17:N). The names of the reporter constructs (loxP-2272, loxP-N, lox2272-N, loxP-HT2, and lox2272-HT2) are shown on the left. Black hexagons denote stop codons. C290C: a 156-bp fragment from human CEP290 C-terminus (aa 2428-2479). Fig.9B The spacers of loxP and lox2272 are fully incompatible with each other and with those of loxm7, loxHT1, and loxHT2. Reporter constructs shown in Fig. 9A were transfected to HEK293T cells with and without a CRE expression vector, and cell lysates were subjected to SDS-PAGE and immunoblotting. C290-C, FLAG, HA, V5, MYC, and β-actin antibodies were used for immunoblotting. A lysate derived from untransfected cells served as the negative control (lane 6), while lysates obtained from cells transfected with MYC-BBS1, FLAG-LZTFL1, and HA- LZTFL1 expression vectors were used as the positive control (lane 12). β-actin was used as a loading control. Fig. 10 shows the design of the lox site incompatibility reporters. Schematics of loxP-2272 are shown as a representative. In the absence of recombination, GFP+C290C fusion proteins (~35 kDa) are produced and translation stops at the end of C290C due to the presence of a STOP codon. If recombination takes place between 15:P and 17:m7 sites, the C290C fragment is excised and the FLAG tag is linked to GFP in-frame, resulting in the production of GFP+FLAG fusion proteins (30 kDa). If recombination takes place between 15:P and 17:HT1, GFP+HA fusion proteins (30 kDa) are produced. Likewise, recombination of 15:P with 17:HT2 and 17:2272 leads to the production of GFP+MYC and GFP+V5 fusion proteins, respectively. Figs.11A-11B shows the CRE-lox mediated reconstitution of large genes: three-AAV set. Fig.11A: Schematic representation of large gene reconstitution by CRE-lox mediated recombination of three AAV vectors. Three gene fragments (CDS1, 2, and 3) are delivered to target cells via 3 separate AAV vectors. CRE recombinase, delivered either separately or as a part of the first vector, facilitates the reconstitution of the expression cassette. The use of non-compatible, reaction- equilibrium modifying lox sites prevents the excision of the floxed fragment as well as reverse reactions. In panel B, the initial 1,923 bp of IFT140 (IFT140-N; with an HA tag), BBS1, and LZTFL1 were used as CDS1, 2, and 3, respectively. SD: splice donor site, SA: splice acceptor site, 15: loxJT15, 17: loxJTZ17, and pA: polyA signal. Fig. 11B Reconstitution and expression of IFT140+BBS1+LZTFL1 fusion proteins using three separate AAV vectors. AAV vectors containing IFT140-N (with an HA tag), BBS1, and LZTFL1 were delivered to 293T cells, and the expression of IFT140+BBS1+LZTFL1 fusion proteins was examined by SDS-PAGE and immunoblotting using HA and LZTFL1 antibodies. Numbers on the right mark the location of protein standards. A separate AAV vector, AAV-EF1α-CRE, was co-transduced to express CRE (lanes 1-7). Lane 1: CDS1 (IFT140-N) only, lane 2: CDS2 (BBS1) only, lane 3: CDS3 (LZTFL1) only, lane 4: CDS1 + CDS2, lane 5: CDS1 + CDS3, lane 6: CDS2 + CDS3, lane 7: CDS1 + CDS2 + CDS3, lane 8: CDS1 + CDS2 + CDS3 (without CRE). Endogenous LZTFL1 (blue arrowheads) was used as a loading control. Figs. 12A-12B. CRE-lox mediated reconstitution of large genes: four- AAV set. Fig. 12A is a schematic representation of large gene reconstitution by CRE-lox mediated recombination of four AAV vectors. A gene-of-interest is split into four fragments (CDS1, 2, 3, and 4) and delivered to target cells via four separate AAV vectors. As a proof-of-principle, the initial 1,923 bp of IFT140 (IFT140-N; with an HA tag), IFT57, BBS5, and LZTFL1 coding sequences were used as CDS1, 2, 3, and 4, respectively. Others are the same as in Fig. 11. Fig. 12B shows reconstitution and expression of IFT140+IFT57+BBS5+LZTFL1 fusion proteins using four separate AAV vectors. AAV vectors containing IFT140-N (with an HA tag), IFT57, BBS5, and LZTFL1 were delivered to 293T cells, and the expression of IFT140+IFT57+BBS5+LZTFL1 fusion proteins (red arrowheads) was examined by SDS-PAGE and immunoblotting using HA and LZTFL1 antibodies. In lanes 1-5, a CRE expression vector (AAV-EF1α-CRE) was co-transduced with the indicated vectors. Endogenous LZTFL1 served as a loading control (blue arrowhead). Numbers on the right mark the location of protein standards. Figs.13A-13B. CRE-lox mediated reconstitution of ABCA4. Fig.13A is a schematic representation of ABCA4 reconstitution by CRE-lox mediated recombination. The ABCA4 CDS (6,819 bp) was split into two segments (3,405 bp for CDS1 and 3,414 bp for CDS2) and delivered to HEK293T cells via two separate AAV vectors. CRE was delivered via a separate AAV vector. CDS1 and 2: coding sequence 1 and 2, EF1α: human elongation factor-1α promoter, ITR: inverted terminal repeat, pA: transcription termination signal, SD: splice donor, SA: splice acceptor. Fig.13B shows expression of full-length ABCA4 by CRE/lox mediated recombination. Dual AAV-ABCA4 vectors depicted in panel A were delivered to HEK293T cells (serotype AAV2), and the production of full-length ABCA4 protein was confirmed by Western blotting (WB). The ABCA4-N antibody detects the N-terminal half of ABCA4, and the ABCA4-C antibody detects the C-terminal half of ABCA4. Numbers on the right mark the location of protein standards. Lane 1: ABCA4-N only, lane 2: ABCA4-C (with loxJTZ17) only, lane 3: ABCA4-C (with loxP) only, lane 4: ABCA4-N and -C (with loxJTZ17), lane 5: ABCA4-N and -C (with loxP), lane 6: ABCA4-N and -C (with loxJTZ17), lane 7: ABCA4-N and -C (with loxP), lane 8: expression plasmids encoding full-length ABCA4 transfected. In lanes 6-8, the CRE expression vector was omitted. Figs. 14A-14D. Reconstitution of IFT140 by CRE-lox mediated recombination and protein trans-splicing. Fig.14A shows schematics of IFT140 reconstitution by CRE-lox mediated recombination of two AAV vectors. Fig.14B shows schematics of IFT140 reconstitution by protein trans-splicing. The immunogen part used to raise the 140-C antibody was marked by a solid line at the bottom. IntN: N-terminal gp41 split intein, IntC: C-terminal gp41 split intein, T2A: T2A “self-cleaving” peptide. Fig. 14C shows production of full-length IFT140 proteins by CRE-lox mediated recombination and protein trans-splicing approaches in 293T cells. HEK293T cells were transduced with dual AAV vectors depicted in panels A and B (with a CMV promoter), and cell lysates were subjected to analysis by immunoblotting with HA and 140-C antibodies. Asterisks indicate unconjugated IFT140 “half” protein products. Lane 1: no transduction (negative control), lane 2: dual AAV-IFT140 N+C CRE-lox set (with a CMV promoter), lane 3: AAV-IFT140N-IntN only, lane 4: AAV-IFT140C-IntC only, lane 5: dual AAV-IFT140 N+C split intein set, and lane 6: pCS2HA-IFT140 plasmid transfected (full-length; positive control). Fig.14D shows production of full-length IFT140 proteins through CRE-lox mediated recombination of dual AAV vectors in mouse retinas. Dual AAV vectors illustrated in panel A were administered via subretinal injection into mouse eyes (serotype: AAV5, dose: 5x109 vs per vector) and retinal protein extracts were subjected to immunoblotting analysis. AAV-IFT140N vectors with both CBh and CMV promoters were injected to explore potential differences in expression levels. Lysates from uninjected eyes were used as a negative control (lanes 1 and 5). β-actin was used as a loading control. Fig.15A-15B illustrate the IFT140 domain organization and the location of the splitting position. Fig.15A: IFT140 domain organization. The N-terminal portion of IFT140 contains 7-blade WD40 repeats, and its C-terminal half consists of nine tetratricopeptide repeats (TPR). Fig.15B: AlphaFold-predicted structural model of IFT140 (identifier: AF-Q96RY7-F1). This model suggests the presence of a WD40-like domain situated in the latter part of the N-terminal half. The red arrows indicate the splitting position (D767/C768) for protein trans-splicing. Figs.16A-16C. Reconstitution of PCDH15 using the gp41 split intein and the CRE/lox unidirectional DNA recombination approaches in 293T cells. Figs. 16A-16B: Strategies for the PCDH15 reconstitution using dual AAV-PCDH15 vectors. PCDH15 CDS was split at E644/G645 for the CRE/lox set (Fig.16A) and at F926/S927 or at F1035/T1036 for the gp41 sets (Fig. 16B). A signal peptide derived from PCDH15 (N-terminal 26 residues) was added to the N-terminus of IntC to facilitate the extracellular translocation of IntC. PCDH15N antibody recognizes the N-terminal half of the protein. A FLAG tag (red) was added to the C-terminus of the protein. IRES: internal ribosome entry site, sig pep: signal peptide for extracelluar translocation. 15: loxJT15, 17: loxJTZ17, SD: splice donor site, SA: splice acceptor site, pA: polyA signal. Fig.16C: Reconstitution of PCDH15 by the CRE/lox approach. HEK293T cells were transfected with AAV- PCDH15 vectors as indicated (lanes 1-3: gp41 926/927 set; lanes 4-6: gp41 1035/1036 set; lanes 7-9: CRE/lox set), and cell lysates were subjected to SDS- PAGE and immunoblotting with PCDH15N and FLAG tag antibodies. The single blue arrowhead marks monomeric forms of PCDH15 N-terminal truncated protein products derived from the gp41N vectors, and the green arrowheads indicate C- terminal truncated proteins from the gp41C vectors. Red arrowheads mark the reconstituted full-length PCDH15 proteins. PCDH15 forms homodimers via its extracellular domain (Kazmierczak et al, 2007). Consistent with this, PCDH15 N- terminal truncated proteins showed a strong tendency to form homodimers even under the denaturing conditions of SDS-PAGE (double blue arrowheads). Interestingly, the quantity of unconjugated PCDH15 C-terminal truncated protein products (green arrowheads) drastically decreases when they are co-expressed with PCDH15_N. Although the reason for this phenomenon is unknown, we speculate that it might be linked to the degradation of reconstituted proteins, possibly due to issues related to protein structure or folding. Figs. 17A-17C. Reconstitution of CDH23 using the CRE/lox unidirectional DNA recombination approach. Fig. 17A is a schematic of the CDH23 reconstitution using triple AAV-CDH23 vectors. CDH23 CDS (10,065 bp) was split into three pieces (E1: 2,176 bp, E2: 4,077 bp, and E3: 3,812 bp), and the CRE gene was included in the 5’ (E1) vector for self-inactivation after recombination. A T2A “self-cleaving” peptide was used for CRE expression. An HA tag was added to the N-terminus of CDH23 for detection (right after the signal peptide). The loxJT15/loxJTZ17 pair was used for the recombination of E1 and E2 vectors, and the lox15:2272/lox17:2272 pair was used for E2 and E3 vector recombination. The incompatibility between the two pairs prevents the recombination between E1 and E3 vectors. Fig. 17B shows Reconstitution of CDH23 by the CRE/lox approach in 293T cells. HEK293T cells were transduced with triple AAV-CDH23 vectors at an MOI of 3x104 (per vector) (lane 1: E1 vector alone; lane 2: E2 vector alone; lane 3: E3 vector alone, lane 4: E1+E3+E3 co-transduced), and cell lysates were subjected to SDS-PAGE and immunoblotting with HA tag antibodies. Lysates from full-length CDH23 expression plasmid transfected cells were used as a positive control (lane 5). Arrowhead marks the reconstituted full-length CDH23 proteins. Fig.17C shows reconstitution of CDH23 by the CRE/lox approach in mouse retinas. Triple AAV- CDH23 vectors were subretinally administered to wild-type mice as indicated (lane 1: E1 vector alone, lane 2: E2 vector alone, lane 3: E3 vector alone, lanes 4- 7: E1+E2+E3) at the dose of 3x109 vg per vector. Treated eyes were collected 2 weeks post-injection and retinal protein extracts were subjected to SDS-PAGE and immunoblotting. Each lane represents individual eyes. Detailed Description The present invention is composed in one embodiment of AAV vectors containing a series of mutant lox sequences and an AAV vector to express CRE recombinase. The lox site sequences described in this invention were developed by combining 2 classes of loxP variants: 1) non-compatible mutant variants of loxP (Figures 1 and 2) reaction equilibrium-modifying mutant variants of loxP (Figure 1B). The canonical loxP site consists of two 13-bp inverted repeats (left and right elements; LE and RE, respectively) separated by an asymmetric 8-bp core/spacer sequence. The asymmetry of the core gives the loxP site directionality. While the left and right elements are the binding sites of the CRE recombinase, the core participates in the strand exchange reaction during recombination. The non-compatible mutant variants of loxP (e.g., loxN and lox2272; Figure 1, or lox 66 and lox 71) have mutations within the core, and these mutations prevent strand exchange (and consequently recombination) between non-compatible lox sites while allowing recombination between homologous sites (Lee and Saito,1998); Siegel et al., 2001; Livet et al., 2007). The reaction equilibrium-modifying mutant variants of loxP (e.g., loxJT15 and loxJTZ17; Figure 1B) have mutations within the either LE or RE but not in both (Thomson et al., 2003; Albert et al., 1995). These single-element mutations do not affect the binding of CRE to the lox site, and recombination between these mutant lox sites is as efficient as wild-type loxP sites. However, recombination between LE and RE single mutants produces an LE/RE double mutant and a canonical loxP site. The presence of mutations in both LE and RE significantly reduces the affinity of CRE to the lox site, making LE/RE double mutants a poor substrate of CRE. The production of LE/RE double mutants as a reaction product drastically alters the reaction equilibrium. While recombination between canonical loxP sites is fully reversible as the initial substrates and the products are the same, the forward reaction is strongly favored over the reverse reaction when LE and RE single mutants are used as substrates because the LE/RE double mutants are a poor substrate of CRE. This causes the CRE-mediated recombination nearly unidirectional and greatly increases the product/substrate ratio at the equilibrium. For example, 2 pairs of lox sites were designed that enable sequence- specific, unidirectional recombination by combining the non-compatible and the reaction equilibrium-modifying mutant variants of loxP (Figure 2). The loxN- based pair (Figure 2A) was generated by replacing the core sequence of loxJT15 and loxJTZ17, which is derived from the canonical loxP, with that of loxN. The lox2272-based pair (Figure 2B) was generated by replacing the core sequence of loxJT15 and loxJTZ17 with that of lox2272. Similarly, the loxHT1- and the loxHT2-based pairs were generated by replacing the core of loxJT15 and loxJTZ17 with that of loxHT1 and loxHT2, respectively (Figure 2C and D). As these new lox site pairs and the original loxJT15:loxJTZ17 pair have non- compatible core sequences, these 5 pairs do not recombine with heterologous pairs and therefore can be used to simultaneously mediate up to 5 sequence-specific recombination reactions. In this disclosure, 3 sets of AAV vectors are described that contain the aforementioned 3 of the 5 mentioned pairs of mutant lox sites to deliver up to 16- kb of genes. The first set is composed of two AAV vectors to deliver up to 8 kb. The second and the third sets are composed of 3 and 4 AAV vectors, respectively, to deliver up to 12 kb and 16 kb. The CRE expression cassette may be delivered via a separate AAV vector or included in one of the AAV vectors to deliver cargo genes if space allows. Definitions The term “AAV” refers to adeno-associated virus, and may be used to refer to the naturally occurring wild-type virus itself or derivatives thereof. The term covers all subtypes, serotypes and pseudotypes, and both naturally occurring and recombinant forms, except where required otherwise. The AAV genome is built of single stranded DNA, and comprises inverted terminal repeats (ITRs) at both ends of the DNA strand, and two open reading frames: rep and cap, encoding replication and capsid proteins, respectively. A foreign polynucleotide can replace the native rep and cap genes. AAVs can be made with a variety of different serotype capsids which have varying transduction profiles or, as used herein, “tropism” for different tissue types. As used herein, the term “serotype” refers to an AAV which is identified by and distinguished from other AAVs based on capsid protein reactivity with defined antisera, e.g., AAV1, AAV2, AAV3, AAV4, AAV5, AAV6, AAV7, AAV8, AAV9, and AAVrh10. For example, serotype AAV2 is used to refer to an AAV which contains capsid proteins encoded from the cap gene of AAV2 and a genome containing 5' and 3' ITR sequences from the same AAV2 serotype. Pseudotyped AAV as refers to an AAV that contains capsid proteins from one serotype and a viral genome including 5'-3' ITRs of a second serotype. Pseudotyped rAAV would be expected to have cell surface binding properties of the capsid serotype and genetic properties consistent with the ITR serotype. Pseudotyped rAAV are produced using standard techniques described in the art. The term “about” is used herein to mean a value that is ±10% of the recited value. As used herein, by “administering” is meant a method of giving a dosage of a composition described herein (e.g., rAAVs or a pharmaceutical composition thereof) to a subject. The compositions utilized in the methods described herein can be administered by any suitable route, including, for example, by inhalation, nebulization, aerosolization, intranasally, intratracheally, intrabronchially, orally, parenterally (e.g., intravenously, subcutaneously, or intramuscularly), orally, nasally, rectally, topically, or buccally. In some embodiments, a composition described herein is administered in aerosolized particles intratracheally and/or intrabronchially using an atomizer sprayer (e.g., with a MADgic® laryngo- tracheal mucosal atomization device). The compositions utilized in the methods described herein can also be administered locally or systemically. The method of administration can vary depending on various factors (e.g., the components of the composition being administered and the severity of the condition being treated). A “control element” or “control sequence” is a nucleotide sequence involved in an interaction of molecules that contributes to the functional regulation of a polynucleotide, including replication, duplication, transcription, splicing, translation, or degradation of the polynucleotide. The regulation may affect the frequency, speed, or specificity of the process, and may be enhancing or inhibitory in nature. Control elements known in the art include, for example, transcriptional regulatory sequences such as promoters and enhancers. A promoter is a DNA region capable under certain conditions of binding RNA polymerase and initiating transcription of a coding region usually located downstream (in the 3' direction) from the promoter. Promoters include AAV promoters, e.g., P5, P19, P40 and AAV ITR promoters, as well as heterologous promoters. An “expression vector” is a vector comprising a region which encodes a polypeptide of interest, and is used for effecting the expression of the protein in an intended target cell. An expression vector also comprises control elements operatively linked to the encoding region to facilitate expression of the protein in the target. The combination of control elements and a gene or genes to which they are operably linked for expression is sometimes referred to as an “expression cassette,” a large number of which are known and available in the art or can be readily constructed from components that are available in the art. A “gene” refers to a polynucleotide containing at least one open reading frame that is capable of encoding a particular protein after being transcribed and translated. The term “gene delivery” refers to the introduction of an exogenous polynucleotide into a cell for gene transfer, and may encompass targeting, binding, uptake, transport, localization, replicon integration and expression. The term “gene transfer” refers to the introduction of an exogenous polynucleotide into a cell which may encompass targeting, binding, uptake, transport, localization and replicon integration, but is distinct from and does not imply subsequent expression of the gene. The term “gene expression” or “expression” refers to the process of gene transcription, translation, and post-translational modification. A “helper virus” for AAV refers to a virus that allows AAV (e.g., wild- type AAV) to be replicated and packaged by a mammalian cell. A variety of such helper viruses for AAV are known in the art, including adenoviruses, herpes viruses and poxviruses such as vaccinia. The adenoviruses encompass a number of different subgroups, although Adenovirus type 5 of subgroup C is most commonly used. Numerous adenoviruses of human, non-human mammalian and avian origin are known and available from depositories such as the ATCC. Viruses of the herpes family include, for example, herpes simplex viruses (HSV) and Epstein-Barr viruses (EBV), as well as cytomegaloviruses (CMV) and pseudorabies viruses (PRV); which are also available from depositories such as ATCC. “Heterologous” means derived from a genotypically distinct entity from that of the rest of the entity to which it is compared. For example, a polynucleotide introduced by genetic engineering techniques into a different cell type is a heterologous polynucleotide (and, when expressed, can encode a heterologous polypeptide). “Host cells,” “cell lines,” “cell cultures,” “packaging cell line” and other such terms denote eukaryotic cells, e.g., mammalian cells, such as human cells, useful in the present disclosure. These cells can be used as recipients for recombinant vectors, viruses or other transfer polynucleotides, and include the progeny of the original cell that was transduced. It is understood that the progeny of a single cell may not necessarily be completely identical (in morphology or in genomic complement) to the original parent cell. An “isolated” plasmid, virus, or other substance refers to a preparation of the substance devoid of at least some of the other components that may also be present where the substance or a similar substance naturally occurs or is initially prepared from. Thus, for example, an isolated substance may be prepared by using a purification technique to enrich it from a source mixture. Enrichment can be measured on an absolute basis, such as weight per volume of solution, or it can be measured in relation to a second, potentially interfering substance present in the source mixture. Increasing enrichments of the embodiments of this disclosure are increasingly more some. Thus, for example, a 2-fold enrichment is some, 10-fold enrichment is more some, 100-fold enrichment is more some, 1000-fold enrichment is even more some. As used herein, the term “operable linkage” or “operably linked” refers to a physical or functional juxtaposition of the components so described as to permit them to function in their intended manner. More specifically, for example, two DNA sequences operably linked means that the two DNAs are arranged (cis or trans) in such a relationship that at least one of the DNA sequences is able to exert a physiological effect upon the other sequence. For example, an enhancer and/or a promoter can be operably linked with a transgene (e.g., a therapeutic transgene). “Packaging” as used herein refers to a series of subcellular events that results in the assembly and encapsidation of a viral vector, particularly an AAV vector. Thus, when a suitable vector is introduced into a packaging cell line under appropriate conditions, it can be assembled into a viral particle. Functions associated with packaging of viral vectors, particularly AAV vectors, are described herein and in the art. The term “polynucleotide” refers to a polymeric form of nucleotides of any length, including deoxyribonucleotides or ribonucleotides, or analogs thereof. A polynucleotide may comprise modified nucleotides, such as methylated or capped nucleotides and nucleotide analogs, and may be interrupted by non- nucleotide components. If present, modifications to the nucleotide structure may be imparted before or after assembly of the polymer. The term polynucleotide, as used herein, refers interchangeably to double- and single-stranded molecules. Unless otherwise specified or required, any embodiment of the disclosure described herein that is a polynucleotide encompasses both the double-stranded form and each of two complementary single-stranded forms known or predicted to make up the double-stranded form. The terms "nucleic acid," "polynucleotide," and "oligonucleotide" are used interchangeably and refer to a deoxyribonucleotide or ribonucleotide polymer, in linear or circular conformation, and in either single-or double-stranded form. For the purposes of the present disclosure, these terms are not to be construed as limiting with respect to the length of a polymer. The terms can encompass known analogues of natural nucleotides, as well as nucleotides that are modified in the base, sugar and/or phosphate moieties (e.g., phosphorothioate backbones). In general, an analogue of a particular nucleotide has the same base-pairing specificity; i.e., an analogue of A will base-pair with T. The terms “polypeptide” and “protein” are used interchangeably herein to refer to polymers of amino acids of any length. The terms also encompass an amino acid polymer that has been modified; for example, disulfide bond formation, glycosylation, acetylation, phosphorylation, lipidation, or conjugation with a labeling component. Polypeptides such as “ABCA4” and the like, when discussed in the context of gene therapy and compositions therefor, refer to the respective intact polypeptide, or any fragment or genetically engineered derivative thereof that retains the desired biochemical function of the intact protein. Similarly, references to genes for use in gene therapy (typically referred to as “transgenes” to be delivered to a recipient cell), include polynucleotides encoding the intact polypeptide or any fragment or genetically engineered derivative possessing the desired biochemical function. By “pharmaceutical composition” is meant any composition that contains a therapeutically or biologically active agent (e.g., a polynucleotide comprising a transgene or a portion thereof), either incorporated into a viral vector (e.g., an rAAV vector) or independent of a viral vector (e.g., incorporated into a liposome, microparticle, or nanoparticle)) that is suitable for administration to a subject. Any of these formulations can be prepared by well-known and accepted methods of art. See, for example, Remington: The Science and Practice of Pharmacy (21st ed.), ed. A.R. Gennaro, Lippincott Williams & Wilkins, 2005, and Encyclopedia of Pharmaceutical Technology, ed. J. Swarbrick, Informa Healthcare, 2006, each of which is hereby incorporated by reference. By “pharmaceutically acceptable diluent, excipient, carrier, or adjuvant” is meant a diluent, excipient, carrier, or adjuvant which is physiologically acceptable to the subject while retaining the therapeutic properties of the pharmaceutical composition with which it is administered. “Recombinant,” as applied to a polynucleotide means that the polynucleotide is the product of various combinations of cloning, restriction and/or ligation steps, and other procedures that result in a construct that is distinct from a polynucleotide found in nature. A recombinant virus is a viral particle comprising a recombinant polynucleotide. The terms respectively include replicates of the original polynucleotide construct and progeny of the original virus construct. By “recombinant adeno-associated virus (AAV)” or “rAAV vector” is meant a recombinantly-produced AAV or AAV particle that comprises a polynucleotide sequence not of AAV origin (e.g., a polynucleotide comprising a transgene, which may be operably linked to one or more enhancer and/or promoters) to be delivered into a cell, either in vivo, ex vivo, or in vitro. The rAAV may use naturally occurring capsid proteins from any AAV serotype. In some embodiments, non-naturally occurring (e.g., chimeric) capsids may be used in the rAAVs described herein. By “reference” is meant any sample, standard, or level that is used for comparison purposes. A “normal reference sample” or a “wild-type reference sample” can be, for example, a sample from a subject not having the disorder (e.g., retinal dysfunction). A “positive reference” sample, standard, or value is a sample, standard, value, or number derived from a subject that is known to have a disorder, which may be matched to a sample of a subject by at least one of the following criteria: age, weight, disease stage, and overall health. The terms “subject” and “patient” are used interchangeably herein to refer to any mammal (e.g., a human, a primate, a cat, a dog, a ferret, a cow, a horse, a pig, a goat, a rat, or a mouse). For example, the subject is a human. A “terminator” refers to a polynucleotide sequence that tends to diminish or prevent read-through transcription (i.e., it diminishes or prevent transcription originating on one side of the terminator from continuing through to the other side of the terminator). The degree to which transcription is disrupted is typically a function of the base sequence and/or the length of the terminator sequence. In particular, as is well known in numerous molecular biological systems, particular DNA sequences, generally referred to as “transcriptional termination sequences” are specific sequences that tend to disrupt read-through transcription by RNA polymerase, presumably by causing the RNA polymerase molecule to stop and/or disengage from the DNA being transcribed. Typical example of such sequence- specific terminators include polyadenylation (“polyA”) sequences, e.g., SV40 polyA. In addition to or in place of such sequence-specific terminators, insertions of relatively long DNA sequences between a promoter and a coding region also tend to disrupt transcription of the coding region, generally in proportion to the length of the intervening sequence. This effect presumably arises because there is always some tendency for an RNA polymerase molecule to become disengaged from the DNA being transcribed, and increasing the length of the sequence to be traversed before reaching the coding region would generally increase the likelihood that disengagement would occur before transcription of the coding region was completed or possibly even initiated. Terminators may thus prevent transcription from only one direction (“uni-directional” terminators) or from both directions (“bi-directional” terminators), and may be comprised of sequence- specific termination sequences or sequence-non-specific terminators or both. A variety of such terminator sequences are known in the art; and illustrative uses of such sequences within the context of the present disclosure are provided below. A “therapeutic gene,” “prophylactic gene,” “target polynucleotide,” “transgene,” “gene of interest” and the like generally refer to a gene or genes to be transferred using a vector. Typically, in the context of the present disclosure, such genes are located within the rAAV vector (which vector is flanked by inverted terminal repeat (ITR) regions and thus can be replicated and encapsidated into rAAV particles). Target polynucleotides can be used in this disclosure to generate rAAV vectors for a number of different applications. Such polynucleotides include, but are not limited to: (i) polynucleotides encoding proteins useful in other forms of gene therapy to relieve deficiencies caused by missing, defective or sub-optimal levels of a structural protein or enzyme; (ii) polynucleotides that are transcribed into anti-sense molecules; (iii) polynucleotides that are transcribed into decoys that bind transcription or translation factors; (iv) polynucleotides that encode cellular modulators such as cytokines; (v) polynucleotides that can make recipient cells susceptible to specific drugs, such as the herpes virus thymidine kinase gene; (vi) polynucleotides for cancer therapy, such as E1A tumor suppressor genes or p53 tumor suppressor genes for the treatment of various cancers; and (vii) polynucleotides for gene editing (e.g., CRISPR). To effect expression of the transgene in a recipient host cell, it is in one embodiment operably linked to a promoter, either its own or a heterologous promoter. A large number of suitable promoters are known in the art, the choice of which depends on the desired level of expression of the target polynucleotide; whether one desires constitutive expression, inducible expression, cell-specific or tissue-specific expression, etc. The rAAV vector may also contain a selectable marker. By “therapeutically effective amount” is meant the amount of a composition administered to improve, inhibit, or ameliorate a condition of a subject, or a symptom of a disorder or disease, in a clinically relevant manner. Any improvement in the subject is considered sufficient to achieve treatment. In one embodiment, an amount sufficient to treat is an amount that reduces, inhibits, or prevents the occurrence or one or more symptoms of a disease or disorder or is an amount that reduces the severity of, or the length of time during which a subject suffers from, one or more symptoms of the disease or disorder (e.g., by at least about 10%, about 20%, or about 30%, or by at least about 50%, about 60%, or about 70%, or by at least about 80%, about 90%, about 95%, about 99%, or more, relative to a control subject that is not treated with a composition described herein). An effective amount of the pharmaceutical composition used to practice the methods described herein varies depending upon the manner of administration and the age, body weight, and general health of the subject being treated. A physician or researcher can decide the appropriate amount and dosage regimen. In particular, a "therapeutically effective amount" refers to an amount effective, at dosages and for periods of time necessary, to achieve the desired therapeutic result. A therapeutically effective amount is also one in which any toxic or detrimental effects of the vector(s)are outweighed by the therapeutically beneficial effects. As used herein, an "effective amount" or a "therapeutically effective amount" of a set of vectors, e.g., a recombinant AAV encoding a portion of a gene product, refers to an amount of the set that alleviates, in whole or in part, symptoms associated with the disorder or condition, or halts or slows further progression or worsening of those symptoms, or prevents or provides prophylaxis for the disorder or condition, e.g., an amount that is effective to prevent, inhibit or treat in the individual one or more symptoms. “Transduction” or “transducing” as used herein, are terms referring to a process for the introduction of an exogenous polynucleotide, e.g., a transgene in rAAV, into a host cell leading to expression of the polynucleotide, e.g., the transgene in the cell. The process generally includes 1) endocytosis of the AAV after it has bound to a cell surface receptor, 2) escape from endosomes or other intracellular compartments in the cytosol of a cell, 3) trafficking of the viral particle or viral genome to the nucleus, 4) uncoating of the virus particles, and generation of expressible double stranded AAV genome forms, including circular intermediates. The rAAV expressible double stranded form may persist as a nuclear episome or optionally may integrate into the host genome. The alteration of any or a combination of endocytosis of the AAV after it has bound to a cell surface receptor, escape from endosomes or other intracellular compartments to the cytosol of a cell, trafficking of the viral particle or viral genome to the nucleus, or uncoating of the virus particles, and generation of expressive double stranded AAV genome forms, including circular intermediates, may result in altered expression levels or persistence of expression, or altered trafficking to the nucleus, or altered types or relative numbers of host cells or a population of cells expressing the introduced polynucleotide. Altered expression or persistence of a polynucleotide introduced via rAAV can be determined by methods well known to the art including, but not limited to, protein expression, e.g., by ELISA, flow cytometry and Western blot, measurement of DNA and RNA production by hybridization assays, e.g., Northern blots, Southern blots and gel shift mobility assays, or quantitative or non-quantitative reverse transcription, polymerase chain reaction (PCR), or digital droplet PCR assays. “Treatment” of an individual or a cell is any type of intervention in an attempt to alter the natural course of the individual or cell at the time the treatment is initiated, e.g., eliciting a prophylactic, curative or other beneficial effect in the individual. For example, treatment of an individual may be undertaken to decrease or limit the pathology caused by any pathological condition, including (but not limited to) an inherited or induced genetic deficiency, infection by a viral, bacterial, or parasitic organism, a neoplastic or aplastic condition, or an immune system dysfunction such as autoimmunity or immunosuppression. Treatment includes (but is not limited to) administration of a composition, such as a pharmaceutical composition, and administration of compatible cells that have been treated with a composition. Treatment may be performed either prophylactically or therapeutically; that is, either prior or subsequent to the initiation of a pathologic event or contact with an etiologic agent. Treatment may reduce one or more symptoms of a pathological condition. Detecting an improvement in, or the absence of, one or more symptoms of a disorder, indicates successful treatment. For example, "treating" or "treatment" within the meaning herein refers to an alleviation of symptoms associated with a disorder or disease, "inhibiting" means inhibition of further progression or worsening of the symptoms associated with the disorder or disease, and "preventing" refers to prevention of the symptoms associated with the disorder or disease. A “variant” refers to a polynucleotide or a polypeptide that is substantially homologous to a native or reference polynucleotide or polypeptide. For example, a variant polynucleotide may be substantially homologous to a native or reference polynucleotide, but which has a polynucleotide sequence different from that of the native or reference polynucleotide because of one or a plurality of deletions, insertions, and/or substitutions. In another example, a variant polypeptide may be substantially homologous to a native or reference polypeptide, but which has an amino acid sequence different from that of the native or reference polypeptide because of one or a plurality of deletions, insertions, and/or substitutions. Variant polypeptide-encoding polynucleotide sequences encompass sequences that comprise one or more additions, deletions, or substitutions of nucleotides when compared to a native or reference polynucleotide sequence, but that encode a variant protein or fragment thereof that retains activity. A wide variety of mutagenesis approaches are known in the art and can be applied by a person of ordinary skill in the art. A variant polynucleotide or polypeptide sequence can be at least 80%, at least 85%, at least at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or more, identical to a native or reference sequence. The degree of homology (percent identity) between a native and a variant sequence can be determined, for example, by comparing the two sequences using freely available computer programs commonly employed for this purpose on the world wide web (e.g., BLASTp or BLASTn with default settings). A “vector” as used herein refers to a macromolecule or association of macromolecules that comprises or associates with a polynucleotide and which can be used to mediate delivery of the polynucleotide to a cell, either in vitro or in vivo. Illustrative vectors include, for example, plasmids, viral vectors, liposomes and other gene delivery vehicles. The polynucleotide to be delivered, sometimes referred to as a transgene, may comprise a coding sequence of interest in gene therapy (such as a gene encoding a protein of therapeutic or interest), a coding sequence of interest in vaccine development (such as a polynucleotide expressing a protein, polypeptide or peptide suitable for eliciting an immune response in a mammal), and/or a selectable or detectable marker. Definitions As used herein, "individual" (as in the subject of the treatment) means a mammal. Mammals include, for example, humans; non-human primates, e.g., apes and monkeys; and non-primates, e.g., dogs, cats, rats, mice, cattle, horses, sheep, and goats. Non-mammals include, for example, fish and birds. The term "disease" or "disorder" are used interchangeably, and are used to refer to diseases or conditions wherein lack of or reduced amounts of a specific gene product, e.g., a lysosomal storage enzyme, plays a role in the disease such that a therapeutically beneficial effect can be achieved by supplementing, e.g., to at least 1% of normal levels. "Substantially" as the term is used herein means completely or almost completely; for example, a composition that is "substantially free" of a component either has none of the component or contains such a trace amount that any relevant functional property of the composition is unaffected by the presence of the trace amount, or a compound is "substantially pure" is there are only negligible traces of impurities present. An "AAV virus" refers to a viral particle composed of at least one AAV capsid protein and an encapsidated polynucleotide. If the particle comprises a heterologous polynucleotide (i.e., a polynucleotide other than a wild-type AAV genome such as a transgene to be delivered to a mammalian cell), it is typically referred to as "rAAV". An AAV "capsid protein" includes a capsid protein of a wild-type AAV, as well as modified forms of an AAV capsid protein which are structurally and or functionally capable of packaging a rAAV genome and bind to at least one specific cellular receptor which may be different than a receptor employed by wild type AAV. A modified AAV capsid protein includes a chimeric AAV capsid protein such as one having amino acid sequences from two or more serotypes of AAV, e.g., a capsid protein formed from a portion of the capsid protein from AAV9 fused or linked to a portion of the capsid protein from AAV- 2, and a AAV capsid protein having a tag or other detectable non-AAV capsid peptide or protein fused or linked to the AAV capsid protein, e.g., a portion of an antibody molecule which binds a receptor other than the receptor for AAV9, such as the transferrin receptor, may be recombinantly fused to the AAV9 capsid protein. A "pseudotyped" rAAV is an infectious virus having any combination of an AAV capsid protein and an AAV genome. Capsid proteins from any AAV serotype may be employed with a rAAV genome which is derived or obtainable from a wild-type AAV genome of a different serotype or which is a chimeric genome, i.e., formed from AAV DNA from two or more different serotypes, e.g., a chimeric genome having 2 inverted terminal repeats (ITRs), each ITR from a different serotype or chimeric ITRs. The use of chimeric genomes such as those comprising ITRs from two AAV serotypes or chimeric ITRs can result in directional recombination which may further enhance the production of transcriptionally active intermolecular concatamers. Thus, the 5’ and 3’ ITRs within a rAAV vector of the invention may be homologous, i.e., from the same serotype, heterologous, i.e., from different serotypes, or chimeric, i.e., an ITR which has ITR sequences from more than one AAV serotype. The terms "polypeptide," "peptide" and "protein" are used interchangeably to refer to a polymer of amino acid residues. The term also applies to amino acid polymers in which one or more amino acids are chemical analogues or modified derivatives of corresponding naturally-occurring amino acids. The term "sequence" refers to a nucleotide sequence of any length, which can be DNA or RNA; can be linear, circular or branched and can be either single- stranded or double stranded. The term "donor sequence" refers to a nucleotide sequence that is inserted into a genome. A donor sequence can be of any length, for example between 2 and 10,000 nucleotides in length (or any integer value therebetween or thereabove), preferably between about 100 and 1,000 nucleotides in length (or any integer therebetween), more preferably between about 200 and 500 nucleotides in length. A "homologous, non-identical sequence" refers to a first sequence which shares a degree of sequence identity with a second sequence, but whose sequence is not identical to that of the second sequence. For example, a polynucleotide comprising the wild-type sequence of a mutant gene is homologous and non- identical to the sequence of the mutant gene. In certain embodiments, the degree of homology between the two sequences is sufficient to allow homologous recombination therebetween, utilizing normal cellular mechanisms. Two homologous non-identical sequences can be any length and their degree of non- homology can be as small as a single nucleotide (e.g., for correction of a genomic point mutation by targeted homologous recombination) or as large as 10 or more kilobases (e.g., for insertion of a gene at a predetermined ectopic site in a chromosome). Two polynucleotides comprising the homologous non-identical sequences need not be the same length. For example, an exogenous polynucleotide (i.e., donor polynucleotide) of between 20 and 10,000 nucleotides or nucleotide pairs can be used. A "disease associated gene" is one that is defective in some manner in, for example, a monogenic disease. An "exogenous" molecule is a molecule that is not normally present in a cell, but can be introduced into a cell by one or more genetic, biochemical or other methods. "Normal presence in the cell" is determined with respect to the particular developmental stage and environmental conditions of the cell. Thus, for example, a molecule that is present only during embryonic development of muscle is an exogenous molecule with respect to an adult muscle cell. Similarly, a molecule induced by heat shock is an exogenous molecule with respect to a non-heat- shocked cell. An exogenous molecule can comprise, for example, a functioning version of a malfunctioning endogenous molecule or a malfunctioning version of a normally-functioning endogenous molecule. An exogenous molecule can be, among other things, a small molecule, such as is generated by a combinatorial chemistry process, or a macromolecule such as a protein, nucleic acid, carbohydrate, lipid, glycoprotein, lipoprotein, polysaccharide, any modified derivative of the above molecules, or any complex comprising one or more of the above molecules. Nucleic acids include DNA and RNA, can be single-or double-stranded; can be linear, branched or circular; and can be of any length. Nucleic acids include those capable of forming duplexes, as well as triplex-forming nucleic acids. An exogenous molecule can be the same type of molecule as an endogenous molecule, e.g., an exogenous protein or nucleic acid. For example, an exogenous nucleic acid can comprise an infecting viral genome, a plasmid or episome introduced into a cell, or a chromosome that is not normally present in the cell. Methods for the introduction of exogenous molecules into cells are known to those of skill in the art and include, but are not limited to, lipid-mediated transfer (e.g., liposomes, including neutral and cationic lipids), electroporation, direct injection, cell fusion, particle bombardment, calcium phosphate co-precipitation, DEAE-dextran-mediated transfer and viral vector-mediated transfer. An exogenous molecule can also be the same type of molecule as an endogenous molecule but derived from a different species than the cell is derived from. For example, a human nucleic acid sequence may be introduced into a cell line originally derived from a mouse or hamster. By contrast, an "endogenous" molecule is one that is normally present in a particular cell at a particular developmental stage under particular environmental conditions. For example, an endogenous nucleic acid can comprise a chromosome, the genome of a mitochondrion, chloroplast or other organelle, or a naturally- occurring episomal nucleic acid. Vectors For AAV vectors, the genome can include deletions of sequences encoding or promoter sequences for rep, cap, or both,, since the functions provided by these genes can be provided in trans. The resultant vector is referred to as being “defective” in these functions. In order to replicate and package the vector, the missing functions are complemented with a packaging gene, or a plurality thereof, which together encode the necessary functions for the various missing rep and/or cap gene products. The packaging genes or gene cassettes are in one embodiment not flanked by AAV ITRs and in one embodiment do not share any substantial homology with the rAAV genome. Thus, in order to minimize homologous recombination during replication between the vector sequence and separately provided packaging genes, it is desirable to avoid overlap of the two polynucleotide sequences. The level of homology and corresponding frequency of recombination increase with increasing length of homologous sequences and with their level of shared identity. The level of homology that will pose a concern in a given system can be determined theoretically and confirmed experimentally, as is known in the art. Typically, however, recombination can be substantially reduced or eliminated if the overlapping sequence is less than about a 25 nucleotide sequence if it is at least 80% identical over its entire length, or less than about a 50 nucleotide sequence if it is at least 70% identical over its entire length. Of course, even lower levels of homology further reduce the likelihood of recombination. It appears that, even without any overlapping homology, there is some residual frequency of generating replication competent AAV (RCA). Even further reductions in the frequency of generating RCA (e.g., by nonhomologous recombination) can be obtained by “splitting” the replication and encapsidation functions of AAV, as described by Allen et al., WO 98/27204). The rAAV vector construct, and the complementary packaging gene constructs can be implemented in this disclosure in a number of different forms. Viral particles, plasmids, and stably transformed host cells can all be used to introduce such constructs into the packaging cell, either transiently or stably. In certain embodiments of this disclosure, the AAV vectors and complementary packaging gene(s), if any, are provided in the form of bacterial plasmids, AAV particles, or any combination thereof. In other embodiments, either the AAV vector sequence, the packaging gene(s), or both, are provided in the form of genetically altered (e.g., inheritably altered) eukaryotic cells. The development of host cells inheritably altered to express the AAV vector sequence, AAV packaging genes, or both, provides an established source of the material that is expressed at a reliable level. A variety of different genetically altered cells can thus be used in the context of this disclosure. By way of illustration, a mammalian host cell may be used with at least one intact copy of a stably integrated rAAV vector. An AAV packaging plasmid comprising at least an AAV rep gene operably linked to a promoter can be used to supply replication functions (as described in U.S. Pat. No. 5,658,776). Alternatively, a stable mammalian cell line with an AAV rep gene operably linked to a promoter can be used to supply replication functions (see, e.g., Trempe et al., (WO 95/13392); Burstein et al. (WO 98/23018); and Johnson et al. (U.S. Pat. No.5,656,785)). The AAV cap gene, providing the encapsidation proteins as described above, can be provided together with an AAV rep gene or separately (see, e.g., the above-referenced applications and patents as well as Allen et al. (WO 98/27204). Other combinations are possible and included within the scope of this disclosure. Approaches for producing rAAVs, e.g., rAAVs that contain capsid proteins are known in the art. See, e.g., Excoffon et al. Proc. Natl. Acad. Sci. USA 106(10):3865-3870, 2009 and U.S. Patent No. 10,046,016, each of which is incorporated herein by reference in its entirety. Compositions described herein (e.g., rAAVs or pharmaceutical compositions) may be used in vivo as well as ex vivo. In vivo gene therapy comprises administering the vectors of this disclosure directly to a subject. Pharmaceutical compositions can be supplied as liquid solutions or suspensions, as emulsions, or as solid forms suitable for dissolution or suspension in liquid prior to use. For administration into the respiratory tract, one exemplary mode of administration is by aerosol, using a composition that provides either a solid or liquid aerosol when used with an appropriate aerosolubilizer device. Another some mode of administration into the respiratory tract is using a flexible fiberoptic bronchoscope to instill the vectors. A composition described herein (e.g., rAAVs or pharmaceutical compositions) can be administered by any suitable route, e.g., by inhalation, nebulization, aerosolization, intranasally, intratracheally, intrabronchially, orally, parenterally (e.g., intravenously, subcutaneously, or intramuscularly), orally, nasally, rectally, topically, or buccally. They can also be administered locally or systemically. In some embodiments, a composition described herein is administered in aerosolized particles intratracheally and/or intrabronchially using an atomizer sprayer (e.g., with a MADgic® laryngo-tracheal mucosal atomization device). In some embodiments, the composition is administered parentally. In other some embodiments, the composition is administered systemically. Vectors can also be introduced by way of bioprostheses, including, by way of illustration, vascular grafts (PTFE and dacron), heart valves, intravascular stents, intravascular paving as well as other non-vascular prostheses. General techniques regarding delivery, frequency, composition and dosage ranges of vector solutions are within the skill of the art. For administration to the upper (nasal) or lower respiratory tract by inhalation, the compositions described herein (e.g., rAAVs or pharmaceutical compositions) are conveniently delivered from an insufflator, nebulizer or a pressurized pack or other convenient means of delivering an aerosol spray. Pressurized packs may comprise a suitable propellant such as dichlorodifluoromethane, trichlorofluoromethane, dichlorotetrafluoroethane, carbon dioxide or other suitable gas. In the case of a pressurized aerosol, the dosage unit may be determined by providing a valve to deliver a metered amount. Alternatively, for administration by inhalation or insufflation, the composition may take the form of a dry powder, for example, a powder mix of the agent and a suitable powder base such as lactose or starch. The powder composition may be presented in unit dosage form in, for example, capsules or cartridges, or, e.g., gelatine or blister packs from which the powder may be administered with the aid of an inhalator, insufflator or a metered-dose inhaler. For intra-nasal administration, the agent may be administered via nose drops, a liquid spray, such as via a plastic bottle atomizer or metered-dose inhaler. Typical of atomizers are the Mistometer (Wintrop) and the Medihaler (Riker). Administration of the compositions described herein (e.g., rAAVs or pharmaceutical compositions) may be continuous or intermittent, depending, for example, upon the recipient's physiological condition, whether the purpose of the administration is therapeutic or prophylactic, and other factors known to skilled practitioners. The compositions described herein can be administered once, or multiple times (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, or more times), at the same or at different sites. The administration of the agents of the disclosure may be essentially continuous over a preselected period of time or may be in a series of spaced doses. Exemplary rAAV Vectors Adeno-associated viruses of any serotype are suitable to prepare rAAV, since the various serotypes are functionally and structurally related, even at the genetic level. All AAV serotypes apparently exhibit similar replication properties mediated by homologous rep genes; and all generally bear three related capsid proteins such as those expressed in AAV2. The degree of relatedness is further suggested by heteroduplex analysis which reveals extensive cross-hybridization between serotypes along the length of the genome; and the presence of analogous self-annealing segments at the termini that correspond to ITRs. The similar infectivity patterns also suggest that the replication functions in each serotype are under similar regulatory control. Among the various AAV serotypes, AAV2 is most commonly employed. An AAV vector typically comprises a polynucleotide that is heterologous to AAV. The polynucleotide is typically of interest because of a capacity to provide a function to a target cell in the context of gene therapy, such as up- or down-regulation of the expression of a certain phenotype. Such a heterologous polynucleotide or “transgene,” generally is of sufficient length to provide the desired function or encoding sequence. Where transcription of the heterologous polynucleotide is desired in the intended target cell, it can be operably linked to its own or to a heterologous promoter, depending for example on the desired level and/or specificity of transcription within the target cell, as is known in the art. Various types of promoters and enhancers are suitable for use in this context. Constitutive promoters provide an ongoing level of gene transcription, and may be preferred when it is desired that the therapeutic or prophylactic polynucleotide be expressed on an ongoing basis. Inducible promoters generally exhibit low activity in the absence of the inducer, and are up-regulated in the presence of the inducer. They may be preferred when expression is desired only at certain times or at certain locations, or when it is desirable to titrate the level of expression using an inducing agent. Promoters and enhancers may also be tissue-specific: that is, they exhibit their activity only in certain cell types, presumably due to gene regulatory elements found uniquely in those cells. Illustrative examples of promoters are the SV40 late promoter from simian virus 40, the Baculovirus polyhedron enhancer/promoter element, Herpes Simplex Virus thymidine kinase (HSV tk), the immediate early promoter from cytomegalovirus (CMV) and various retroviral promoters including LTR elements. Inducible promoters include heavy metal ion inducible promoters (such as the mouse mammary tumor virus (mMTV) promoter or various growth hormone promoters), and the promoters from T7 phage which are active in the presence of T7 RNA polymerase. By way of illustration, examples of tissue- specific promoters include various surfactin promoters (for expression in the lung), myosin promoters (for expression in muscle), ), rhodopsin kinase (GRK1) promoters (for expression in the retina) and albumin promoters (for expression in the liver). A large variety of other promoters are known and generally available in the art, and the sequences of many such promoters are available in sequence databases such as the GenBank database. Where translation is also desired in the intended target cell, the heterologous polynucleotide will preferably also comprise control elements that facilitate translation (such as a ribosome binding site or “RBS” and a polyadenylation signal). Accordingly, the heterologous polynucleotide generally comprises at least one coding region operatively linked to a suitable promoter, and may also comprise, for example, an operatively linked enhancer, ribosome binding site and poly-A signal. The heterologous polynucleotide may comprise one encoding region, or more than one encoding regions under the control of the same or different promoters. The entire unit, containing a combination of control elements and encoding region, is often referred to as an expression cassette. The heterologous polynucleotide is integrated by recombinant techniques into or in place of the AAV genomic coding region (i.e., in place of the AAV rep and cap genes), but is generally flanked on either side by AAV inverted terminal repeat (ITR) regions. This means that an ITR appears both upstream and downstream from the coding sequence, either in direct juxtaposition, e.g., (although not necessarily) without any intervening sequence of AAV origin in order to reduce the likelihood of recombination that might regenerate a replication-competent AAV genome. However, a single ITR may be sufficient to carry out the functions normally associated with configurations comprising two ITRs (see, for example, WO 94/13788), and vector constructs with only one ITR can thus be employed in conjunction with the packaging and production methods of the present invention. The native promoters for rep are self-regulating, and can limit the amount of AAV particles produced. The rep gene can also be operably linked to a heterologous promoter, whether rep is provided as part of the vector construct, or separately. Any heterologous promoter that is not strongly down-regulated by rep gene expression is suitable; but inducible promoters may be preferred because constitutive expression of the rep gene can have a negative impact on the host cell. A large variety of inducible promoters are known in the art; including, by way of illustration, heavy metal ion inducible promoters (such as metallothionein promoters); steroid hormone inducible promoters (such as the MMTV promoter or growth hormone promoters); and promoters such as those from T7 phage which are active in the presence of T7 RNA polymerase. One sub-class of inducible promoters are those that are induced by the helper virus that is used to complement the replication and packaging of the rAAV vector. A number of helper-virus- inducible promoters have also been described, including the adenovirus early gene promoter which is inducible by adenovirus E1A protein; the adenovirus major late promoter; the herpesvirus promoter which is inducible by herpesvirus proteins such as VP16 or 1CP4; as well as vaccinia or poxvirus inducible promoters. Methods for identifying and testing helper-virus-inducible promoters have been described (see, e.g., WO 96/17947). Thus, methods are known in the art to determine whether or not candidate promoters are helper-virus-inducible, and whether or not they will be useful in the generation of high efficiency packaging cells. Briefly, one such method involves replacing the p5 promoter of the AAV rep gene with the putative helper-virus-inducible promoter (either known in the art or identified using well-known techniques such as linkage to promoter-less “reporter” genes). The AAV rep-cap genes (with p5 replaced), e.g., linked to a positive selectable marker such as an antibiotic resistance gene, are then stably integrated into a suitable host cell (such as the HeLa or A549 cells exemplified below). Cells that are able to grow relatively well under selection conditions (e.g., in the presence of the antibiotic) are then tested for their ability to express the rep and cap genes upon addition of a helper virus. As an initial test for rep and/or cap expression, cells can be readily screened using immunofluorescence to detect Rep and/or Cap proteins. Confirmation of packaging capabilities and efficiencies can then be determined by functional tests for replication and packaging of incoming rAAV vectors. Using this methodology, a helper-virus-inducible promoter derived from the mouse metallothionein gene has been identified as a suitable replacement for the p5 promoter, and used for producing high titers of rAAV particles (as described in WO 96/17947). Removal of one or more AAV genes is in any case desirable, to reduce the likelihood of generating replication-competent AAV (“RCA”). Accordingly, encoding or promoter sequences for rep, cap, or both, may be removed, since the functions provided by these genes can be provided in trans, e.g., in a stable line or via co-transfection. The resultant vector is referred to as being “defective” in these functions. In order to replicate and package the vector, the missing functions are complemented with a packaging gene, or a plurality thereof, which together encode the necessary functions for the various missing rep and/or cap gene products. The packaging genes or gene cassettes are in one embodiment not flanked by AAV ITRs and in one embodiment do not share any substantial homology with the rAAV genome. Thus, in order to minimize homologous recombination during replication between the vector sequence and separately provided packaging genes, it is desirable to avoid overlap of the two polynucleotide sequences. The level of homology and corresponding frequency of recombination increase with increasing length of homologous sequences and with their level of shared identity. The level of homology that will pose a concern in a given system can be determined theoretically and confirmed experimentally, as is known in the art. Typically, however, recombination can be substantially reduced or eliminated if the overlapping sequence is less than about a 25 nucleotide sequence if it is at least 80% identical over its entire length, or less than about a 50 nucleotide sequence if it is at least 70% identical over its entire length. Of course, even lower levels of homology are preferable since they will further reduce the likelihood of recombination. It appears that, even without any overlapping homology, there is some residual frequency of generating RCA. Even further reductions in the frequency of generating RCA (e.g., by nonhomologous recombination) can be obtained by “splitting” the replication and encapsidation functions of AAV, as described by Allen et al., WO 98/27204). The rAAV vector construct, and the complementary packaging gene constructs can be implemented in this invention in a number of different forms. Viral particles, plasmids, and stably transformed host cells can all be used to introduce such constructs into the packaging cell, either transiently or stably. In certain embodiments, the AAV vectors and complementary packaging gene(s), if any, are provided in the form of bacterial plasmids, AAV particles, or any combination thereof. In other embodiments, either the AAV vector sequence, the packaging gene(s), or both, are provided in the form of genetically altered (preferably inheritably altered) eukaryotic cells. The development of host cells inheritably altered to express the AAV vector sequence, AAV packaging genes, or both, provides an established source of the material that is expressed at a reliable level. A variety of different genetically altered cells can thus be used in the context of this invention. By way of illustration, a mammalian host cell may be used with at least one intact copy of a stably integrated rAAV vector. An AAV packaging plasmid comprising at least an AAV rep gene operably linked to a promoter can be used to supply replication functions (as described in U.S. Patent 5,658,776). Alternatively, a stable mammalian cell line with an AAV rep gene operably linked to a promoter can be used to supply replication functions (see, e.g., Trempe et al., WO 95/13392); Burstein et al. (WO 98/23018); and Johnson et al. (U.S. No. 5,656,785). The AAV cap gene, providing the encapsidation proteins as described above, can be provided together with an AAV rep gene or separately (see, e.g., the above-referenced applications and patents as well as Allen et al. (WO 98/27204). Other combinations are possible and included within the scope of this invention. Compositions and Routes of Delivery Any route of administration may be employed so long as that route and the amount administered are prophylactically or therapeutically useful. In vivo administration of the components, e.g., delivered in a viral vector such as an AAV vector(s), and compositions containing them, can be accomplished by any suitable method and technique presently or prospectively known to those skilled in the art. The subject polynucleotides or polypeptides can be formulated in a physiologically- or pharmaceutically-acceptable form and administered by any suitable route known in the art including, for example, oral, nasal, rectal, transdermal, vaginal, and parenteral routes of administration. As used herein, the term parenteral includes subcutaneous, intradermal, intravenous, intramuscular, intraperitoneal, subretinal, intracochlear, intrathecal, and intracisternal administration, such as by injection. Administration of the compositions can be a single administration, or at continuous or distinct intervals as can be readily determined by a person skilled in the art. In one embodiment, a polynucleotide component is stably incorporated into the genome of a person of animal in need of treatment. Methods for providing gene therapy are well known in the art. The compositions can also be administered utilizing liposome and nano- technology, slow release capsules, implantable pumps, and biodegradable containers, and orally or intestinally administered intact plant cells expressing the therapeutic product. These delivery methods can, advantageously, provide a uniform dosage over an extended period of time. Suitable dose ranges for are generally about 103 to 1015 infectious units of viral vector per microliter delivered in 1 to 3000 microliters of single injection volume. For instance, viral genomes or infectious units of vector per micro liter would generally contain about 104, 105, 106, 107, 108, 109, 1010, 1011, 1012, 1013, 1014, 1015, 1016, or1017 viral genomes or infectious units of viral vector delivered in about 10, 50, 100, 200, 500, 1000, or 2000 microliters. It should be understood that the aforementioned dosage is merely an exemplary dosage and those of skill in the art will understand that this dosage may be varied. Effective doses may be extrapolated from dose-responsive curves derived from in vitro or in vivo test systems. In one embodiment, suitable dose ranges are generally about 103 to 1015 infectious units of viral vector per microliter delivered in, for example, 1, 2, 5, 10, 25, 50, 75or 100 or more milliliters, e.g.,1 to 10,000 milliliters or 0.5 to 15 milliliters, of single injection volume. For instance, viral genomes or infectious units of vector per microliter would generally contain about 104, 105, 106, 107, 108, 109, 1010, 1011, 1012, 1013, or 1014 viral genomes or infectious units of viral vector. In one embodiment, suitable dose ranges, generally about 103 to 1015 infectious units of viral vector per microliter delivered in, for example, 1, 2, 5, 10, 25, 50, 75 or 100 or more milliliters, e.g., 1 to 10,000 milliliters or 0.5 to 15 milliliters. For instance, viral genomes or infectious units of vector per microliter would generally contain about 104, 105, 106, 107, 108, 109, 1010, 1011, 1012, 1013, 1014, 1015, 1016, or 1017 viral genomes or infectious units of viral vector, e.g., at least 1.2 x 1011 genomes or infectious units, for instance at least 2 x 1011 up to about 2 x 1012 genomes or infectious units or about 1 x 1013 to about 5 x 1016 genomes or infectious units. . Administration of vectors in accordance with the present disclosure can be achieved by direct injection of the composition or by the use of infusion pumps. For injection, the composition can be formulated in liquid solutions, e.g., in physiologically compatible buffers such as Hank's solution, Ringer's solution or phosphate buffer. In one embodiment, the vectors(s) may be administered by any route including parenterally. In one embodiment, the vector(s) may be administered by subretinal, intracochlear, subcutaneous, intramuscular, or intravenous injection, orally, intrathecally, or intracranially, or by sustained release, e.g., using a subcutaneous implant. The vector(s) may be dissolved or dispersed in a liquid carrier vehicle. For parenteral administration, the active material may be suitably admixed with an acceptable vehicle, e.g., of the vegetable oil variety such as peanut oil, cottonseed oil and the like. Other parenteral vehicles such as organic compositions using solketal, glycerol, formal, and aqueous parenteral formulations may also be used. For parenteral application by injection, the vector(s) may comprise an aqueous solution of a water soluble pharmaceutically acceptable salt of the active acids according to the invention, desirably in a concentration of 0.01-10%, and optionally also a stabilizing agent and/or buffer substances in aqueous solution. Dosage units of the solution may advantageously be enclosed in ampules. The vector(s) may be in the form of an injectable unit dose. Examples of carriers or diluents usable for preparing such injectable doses include diluents such as water, ethyl alcohol, macrogol, propylene glycol, ethoxylated isostearyl alcohol, polyoxyisostearyl alcohol and polyoxyethylene sorbitan fatty acid esters, pH adjusting agents or buffers such as sodium citrate, sodium acetate and sodium phosphate, stabilizers such as sodium pyrosulfite, EDTA, thioglycolic acid and thiolactic acid, isotonic agents such as sodium chloride and glucose, local anesthetics such as procaine hydrochloride and lidocaine hydrochloride. Furthermore, usual solubilizing agents and analgesics may be added. Injections can be prepared by adding such carriers to the enzyme or other active, following procedures well known to those of skill in the art. A thorough discussion of pharmaceutically acceptable excipients is available in REMINGTON'S PHARMACEUTICAL SCIENCES (Mack Pub. Co., N.J. 1991). The pharmaceutically acceptable formulations can easily be suspended in aqueous vehicles and introduced through conventional hypodermic needles or using infusion pumps. Prior to introduction, the formulations can be sterilized, e.g., using filters. When the vector(s) is administered in the form of a subcutaneous implant, the compound is suspended or dissolved in a slowly dispersed material known to those skilled in the art, or administered in a device which slowly releases the active material through the use of a constant driving force such as an osmotic pump. In such cases, administration over an extended period of time is possible. The dosage at which the vector(s) is administered may vary within a wide range and will depend on various factors such as the severity of the disease, the age of the patient, etc., and may have to be individually adjusted. Compositions described herein may be employed in combination with another medicament. The compositions can appear in conventional forms, for example, aerosols, solutions, suspensions, or topical applications, or in lyophilized form. Typical compositions include the vector(s) and a pharmaceutically acceptable excipient which can be a carrier or a diluent. For example, the active agent(s) may be mixed with a carrier, or diluted by a carrier, or enclosed within a carrier. When the active agent is mixed with a carrier, or when the carrier serves as a diluent, it can be solid, semi-solid, or liquid material that acts as a vehicle, excipient, or medium for the active agent. Some examples of suitable carriers are water, salt solutions, alcohols, polyethylene glycols, polyhydroxyethoxylated castor oil, peanut oil, olive oil, gelatin, lactose, terra alba, sucrose, dextrin, magnesium carbonate, sugar, cyclodextrin, amylose, magnesium stearate, talc, gelatin, agar, pectin, acacia, stearic acid or lower alkyl ethers of cellulose, silicic acid, fatty acids, fatty acid amines, fatty acid monoglycerides and diglycerides, pentaerythritol fatty acid esters, polyoxyethylene, hydroxymethylcellulose and polyvinylpyrrolidone. Similarly, the carrier or diluent can include any sustained release material known in the art, such as glyceryl monostearate or glyceryl distearate, alone or mixed with a wax. The formulations can be mixed with auxiliary agents which do not deleteriously react with the vector(s). Such additives can include wetting agents, emulsifying and suspending agents, salt for influencing osmotic pressure, buffers and/or coloring substances preserving agents, sweetening agents or flavoring agents. The compositions can also be sterilized if desired. If a liquid carrier is used, the preparation can be in the form of a liquid such as an aqueous liquid suspension or solution. Acceptable solvents or vehicles include sterilized water, Ringer's solution, or an isotonic aqueous saline solution. The vector(s) may be provided as a powder suitable for reconstitution with an appropriate solution as described above. Examples of these include, but are not limited to, freeze dried, rotary dried or spray dried powders, amorphous powders, granules, precipitates, or particulates. The composition can optionally contain stabilizers, pH modifiers, surfactants, bioavailability modifiers and combinations of these. A unit dosage form can be in individual containers or in multi-dose containers. Compositions contemplated by the present disclosure may include, for example, micelles or liposomes, or some other encapsulated form, or can be administered in an extended release form to provide a prolonged storage and/or delivery effect, e.g., using biodegradable polymers, e.g., polylactide- polyglycolide. Examples of other biodegradable polymers include poly(orthoesters) and poly(anhydrides). Polymeric nanoparticles, e.g., comprised of a hydrophobic core of polylactic acid (PLA) and a hydrophilic shell of methoxy-poly(ethylene glycol) (MPEG), may have improved solubility and targeting to the CNS. Regional differences in targeting between the microemulsion and nanoparticle formulations may be due to differences in particle size. Liposomes are very simple structures consisting of one or more lipid bilayers of amphiphilic lipids, i.e., phospholipids or cholesterol. The lipophilic moiety of the bilayers is turned towards each other and creates an inner hydrophobic environment in the membrane. Liposomes are suitable drug carriers for some lipophilic drugs which can be associated with the non-polar parts of lipid bilayers if they fit in size and geometry. The size of liposomes varies from 20 nm to few μm. Mixed micelles are efficient detergent structures which are composed of bile salts, phospholipids, tri, di- and monoglycerides, fatty acids, free cholesterol and fat soluble micronutrients. As long-chain phospholipids are known to form bilayers when dispersed in water, the preferred phase of short chain analogues is the spherical micellar phase. A micellar solution is a thermodynamically stable system formed spontaneously in water and organic solvents. The interaction between micelles and hydrophobic/lipophilic drugs leads to the formation of mixed micelles (MM), often called swollen micelles, too. In the human body, they incorporate hydrophobic compounds with low aqueous solubility and act as a reservoir for products of digestion, e.g. monoglycerides. Lipid microparticles includes lipid nano- and microspheres. Microspheres are generally defined as small spherical particles made of any material which are sized from about 0.2 to 100 μm. Smaller spheres below 200 nm are usually called nanospheres. Lipid microspheres are homogeneous oil/water microemulsions similar to commercially available fat emulsions, and are prepared by an intensive sonication procedure or high pressure emulsifying methods (grinding methods). The natural surfactant lecithin lowers the surface tension of the liquid, thus acting as an emulsifier to form a stable emulsion. The structure and composition of lipid nanospheres is similar to those of lipid microspheres, but with a smaller diameter. Polymeric nanoparticles serve as carriers for a broad variety of ingredients. The active components may be either dissolved in the polymetric matrix or entrapped or adsorbed onto the particle surface. Polymers suitable for the preparation of organic nanoparticles include cellulose derivatives and polyesters such as poly(lactic acid), poly(glycolic acid) and their copolymer. Due to their small size, their large surface area/volume ratio and the possibility of functionalization of the interface, polymeric nanoparticles are ideal carrier and release systems. If the particle size is below 50 nm, they are no longer recognized as particles by many biological and also synthetic barrier layers, but act similar to molecularly disperse systems. Thus, the composition can be formulated to provide quick, sustained, controlled, or delayed release, or any combination thereof, of the active agent after administration to the individual by employing procedures well known in the art. In one embodiment, the enzyme is in an isotonic or hypotonic solution. In one embodiment, for enzymes that are not water soluble, a lipid based delivery vehicle may be employed, e.g., a microemulsion such as that described in WO 2008/049588, the disclosure of which is incorporated by reference herein, or liposomes. In one embodiment, the preparation can contain an agent, dissolved or suspended in a liquid carrier, such as an aqueous carrier, for aerosol application. The carrier can contain additives such as solubilizing agents, e.g., propylene glycol, surfactants, absorption enhancers such as lecithin (phosphatidylcholine) or cyclodextrin, or preservatives such as parabens. Exemplary Human Nucleotide Sequences and Encoded Proteins The viral vector sets may in one embodiment comprise sequences for a therapeutic gene. In one embodiment, the gene is intraflagellar transport 140 (IFT140), and the nucleotide sequence comprises gcagcagtgt tgacggatac gtgagaagaa aacggcgtgg tagctcggag tgtggaatcg ggcgcgaacc tgagttctga gaagtgtgga agcacgtctg aggcaagcgg aataacctgg cccccgacgc tcgggcctcg gagctgcacg tgcgtgcccg atcgccttcg gctctttccg gccgctcggg gcgcttcggg agtcctcggg gccgcctcgc tcaccttcgg ctatttccgc gttcctggcg cgccgttgtc ccggcaacgc gcggcggctc agcggcctgg cagaggtttc agcgctgagg aggcctgagt tccgtcatgg ccctctatta tgaccaccag atagaagccc cggatgcagc agggtcaccc tcatttatca gctggcaccc tgtccatcca ttcttggcag ttgcttacat cagcacaacc tcaacaggca gcgtggatat ttacctggag caaggggagt gcgtgccaga tacacacgtc gagaggccgt tccgggttgc ttccctgtgc tggcacccga cgcggctggt gctggctgtg ggctgggaga ctggagaagt gacggtgttt aacaagcagg acaaggagca gcacacgatg cccctgacac acacagccga catcaccgtg ctccgttgga gccccagtgg aaactgcctg ctgtctgggg acaggcttgg tgtcttgctc ttgtggaggt tggaccaaag gggccgagtg caagggacgc ctctgctgaa acacgagtat gggaaacacc tcacgcactg catcttccgg ctcccccctc ctggcgagga cctggttcag ttggcaaagg cagctgtgag cggtgatgag aaagccctgg acatgtttaa ctggaagaag agcagttctg gaagtttgct gaagatgggg tctcacgagg ggctgttgtt ctttgtcagt ctgatggacg ggacagtgca ctatgtggat gagaagggca agaccactca ggtggtgtcc gcagacagca cgattcagat gctgttctac atggagaaga gggaggcact ggtggtggtc acagagaacc tccggctgtc cctgtacacg gtgcctcctg agggcaaagc agaagaagtg atgaaggtca agctgagcgg gaaaaccggc cgccgggcag acatcgcttt gattgaaggc agccttctcg tgatggccgt cggggaggct gccctcagat tctgggacat agaacgagga gagaattata tactgagtcc agatgagaag tttggctttg agaaaggaga gaatatgaac tgtgtgtgtt actgtaaagt caaaggtctt ctggccgctg gtaccgacag agggcgagta gccatgtgga ggaaagtacc agacttcctg ggcagccccg gggcagaggg caaggacagg tgggcccttc agacccctac cgagctccaa ggaaacatca cgcaaatcca gtggggttcc aggaagaacc tgctggcagt gaacagcgtc atctccgtgg ccatcctcag cgagcgggcc atgtcgtcac acttccacca gcaagtggcc gccatgcagg tctccccgag tctgctgaat gtgtgcttcc tgtccacggg ggtcgcacac agcctgcgca ccgacatgca catcagtgga gtgtttgcca ccaaggatgc tgtcgcagtc tggaacggaa ggcaggtggc gatcttcgag ctttctggag ccgcgatacg gagtgcaggg accttcttgt gtgagacgcc tgtgttagca atgcatgaag aaaacgttta cacggtggag tcaaaccgag ttcaagttcg aacctggcag gggactgtca aacaactcct ccttttctcg gagactgagg ggaatccctg cttcttggac atctgtggga atttcctggt tgtagggaca gacttggctc actttaaaag ctttgatctt tcccgaagag aggccaaagc acactgtagc tgcaggagcc tggcggagct ggtccctggg gtggggggca tcgcttctct gcggtgcagc agcagcggga gcaccatcag catcctcccc agcaaggctg acaacagccc tgattccaaa atctgcttct acgatgttga aatggacaca gtgaccgtct ttgacttcaa gactggacaa attgatcgga gagagacgct gtcctttaat gagcaagaga ctaataagag ccacctcttt gtggatgagg gactgaaaaa ttatgttccc gtgaaccact tctgggacca gagtgagccc cggctgtttg tatgcgaagc cgtgcaggag acgccgcgct cccagcctca gtctgcaaac gggcagcccc aagatgggcg cgctggccct gcggcagatg ttttgatcct gtccttcttc atttccgaag agcacggctt cctgcttcat gagagcttcc cccggcctgc cacctcccac agtctcctgg ggatggaagt gccttattac tacttcacaa gaaagcccga agaagcagac agagaagacg aggtggagcc tgggtgccac cacatccctc agatggtgtc caggagaccc ctgcgagact ttgtggggct ggaggactgc gacaaggcca cccgggacgc catgctccac ttcagcttct ttgtcaccat aggagacatg gacgaagcct tcaaatccat caagctcatc aaaagtgagg ccgtctggga gaacatggcg cgcatgtgcg tgaagaccca gcggctggac gtggccaagg tgtgcctggg gaacatgggc catgcccgcg gggcccgagc gctgcgtgag gcggagcagg agccggagct agaggcccgc gtggccgtgc tggccacgca gctgggcatg ctggaggacg ccgagcagct gtacaggaag tgcaagcgcc acgacctcct gaacaagttc taccaggctg cgggccggtg gcaggaggcc ctccaggtag ccgagcacca cgatcgcgtg cacctgcgca gcacctacca ccgctatgcc gggcacctgg aggccagcgc cgactgcagc cgggccctca gttactacga gaagtcggac acgcaccgct tcgaggtgcc caggatgctg tcggaggacc tgccgtccct ggagctctac gtgaataaaa tgaaggataa gaccctgtgg cggtggtggg cgcagtacct ggagagccag ggcgagatgg acgccgcgct gcactactac gagctggccc gggaccactt ctccctggtc cgcatccact gcttccaggg caatgtccag aaggctgcgc aaatagccaa cgagacagga aacctggcgg cctcctacca cctcgcccgc cagtacgaga gccaggagga ggtcgggcag gcggtgcact tctacacccg ggcacaggcc ttcaagaatg ccatccgcct gtgcaaggag aacggcctgg acgaccagct catgaacttg gccctgctga gctcccccga ggacatgatc gaggcggccc gatactacga ggagaagggc gtgcagatgg acagggcggt catgctgtac cacaaggctg gccacttctc caaggccctg gagctggcct ttgccaccca gcagtttgtg gccctacagc tcatagcaga ggacctggat gagacgtcag accctgcgct cctggcccgc tgctccgact tcttcatcga gcacagtcag tacgagaggg cggtagagct gctgctggct gccaggaagt atcaggaagc cctgcagctg tgcctggggc agaacatgag catcaccgag gagatggcgg aaaagatgac cgtggccaag gactcctcgg acctgcctga ggagtcgcgg cgggagctgc tggagcagat agcagactgc tgcatgcgcc agggcagcta ccacctggcc accaagaagt acacgcaggc cggcaacaag ctgaaggcca tgagggcgct gctcaaatcc ggagacacgg agaaaatcac gttcttcgcg agcgtgtcca ggcagaagga aatctacatc atggctgcta actacctgca gtccctggac tggcggaagg agccggagat catgaagaac atcatcggct tctacaccaa ggggcgggcc ctggacctcc tggctggctt ttatgacgct tgtgcccagg tggagattga tgaataccag aactacgaca aagcccacgg ggcgctgacc gaggcctaca agtgcctggc caaggccaag gccaagagcc ccctggacca ggagaccagg ctggcgcagc tgcagagcag gatggcactg gtgaagaggt tcatccaggc ccgcaggacg tacacagagg accccaagga gtccatcaag cagtgtgagc tgctcctgga ggaaccagac ctggacagca ccatccgcat cggggacgtc tatggcttcc tggtggagca ctacgtgcgg aaggaggaat accagacggc ctacagattc ctggaggaga tgcggcggcg gcttcccttg gccaacatgt cctactacgt gagcccgcag gccgtggacg ccgtgcaccg ggggctgggt ctcccactgc cacgcaccgt ccccgagcag gtccgccaca acagcatgga ggacgccagg gagctggacg aggaggtggt ggaagaggca gatgacgacc cctgaggggc ctgggcccca ggaccagcgt gctgctgcag aaaggcatct tctggaattt ttttgtcagc tgtggcaaag ccagcatttt tgctgggaaa aaacatgtct gtgttggaat acgcgacaga gctgggcgag aacgcagcgg cccgggccgg cggagggtgt gacccgtctg caccttgctc tgtcccacct gcctctgggt gcccggcagc tccactagat ttttggattc attcctttga agggagtcgg gttcaccctt ccatcgtatt ctcccaacta cacattgtaa agcctgagaa acttctagaa cctcaggaag ctgcagctgg agggctgggg cacctgcccc cctgctcccc acacatcata tcctccccat actcctgcag ggcccacggc tcctgagcaa cagctgggac acccgggcct tggcggctgc accccctgct aggctctgcc caccggccac caacactcct gtaattccaa taaagcagtt tattttctga ga (SEQ ID NO:1), or a nucleotide sequence which has at least 80%, 85%, 87%, 90%, 92%, 93%, 94%, 95%, 98%, 99% or more nucleic acid sequence identity thereto, or a nucleotide sequence that encodes a polypeptide having MALYYDHQIEAPDAAGSPSFISWHPVHPFLAVAYISTTSTGSVD IYLEQGECVPDTHVERPFRVASLCWHPTRLVLAVGWETGEVTVFNKQDKEQHTMPLTH TADITVLRWSPSGNCLLSGDRLGVLLLWRLDQRGRVQGTPLLKHEYGKHLTHCIFRLP PPGEDLVQLAKAAVSGDEKALDMFNWKKSSSGSLLKMGSHEGLLFFVSLMDGTVHYVD EKGKTTQVVSADSTIQMLFYMEKREALVVVTENLRLSLYTVPPEGKAEEVMKVKLSGK TGRRADIALIEGSLLVMAVGEAALRFWDIERGENYILSPDEKFGFEKGENMNCVCYCK VKGLLAAGTDRGRVAMWRKVPDFLGSPGAEGKDRWALQTPTELQGNITQIQWGSRKNL LAVNSVISVAILSERAMSSHFHQQVAAMQVSPSLLNVCFLSTGVAHSLRTDMHISGVF ATKDAVAVWNGRQVAIFELSGAAIRSAGTFLCETPVLAMHEENVYTVESNRVQVRTWQ GTVKQLLLFSETEGNPCFLDICGNFLVVGTDLAHFKSFDLSRREAKAHCSCRSLAELV PGVGGIASLRCSSSGSTISILPSKADNSPDSKICFYDVEMDTVTVFDFKTGQIDRRET LSFNEQETNKSHLFVDEGLKNYVPVNHFWDQSEPRLFVCEAVQETPRSQPQSANGQPQ DGRAGPAADVLILSFFISEEHGFLLHESFPRPATSHSLLGMEVPYYYFTRKPEEADRE DEVEPGCHHIPQMVSRRPLRDFVGLEDCDKATRDAMLHFSFFVTIGDMDEAFKSIKLI KSEAVWENMARMCVKTQRLDVAKVCLGNMGHARGARALREAEQEPELEARVAVLATQL GMLEDAEQLYRKCKRHDLLNKFYQAAGRWQEALQVAEHHDRVHLRSTYHRYAGHLEAS ADCSRALSYYEKSDTHRFEVPRMLSEDLPSLELYVNKMKDKTLWRWWAQYLESQGEMD AALHYYELARDHFSLVRIHCFQGNVQKAAQIANETGNLAASYHLARQYESQEEVGQAV HFYTRAQAFKNAIRLCKENGLDDQLMNLALLSSPEDMIEAARYYEEKGVQMDRAVMLY HKAGHFSKALELAFATQQFVALQLIAEDLDETSDPALLARCSDFFIEHSQYERAVELL LAARKYQEALQLCLGQNMSITEEMAEKMTVAKDSSDLPEESRRELLEQIADCCMRQGS YHLATKKYTQAGNKLKAMRALLKSGDTEKITFFASVSRQKEIYIMAANYLQSLDWRKE PEIMKNIIGFYTKGRALDLLAGFYDACAQVEIDEYQNYDKAHGALTEAYKCLAKAKAK SPLDQETRLAQLQSRMALVKRFIQARRTYTEDPKESIKQCELLLEEPDLDSTIRIGDV YGFLVEHYVRKEEYQTAYRFLEEMRRRLPLANMSYYVSPQAVDAVHRGLGLPLPRTVP EQVRHNSMEDARELDEEVVEEADDDP (SEQ ID NO:2), or a polypeptide sequence which has at least 80%, 85%, 87%, 90%, 92%, 93%, 94%, 95%, 98%, 99% or more amino acid sequence identity thereto. In one embodiment, the gene is usherin (USH2A), transcript variant 1, and the nucleotide sequence comprises agttccaaga gggccaccaa gcagaccacg ctctgagctt caggtaacca agtgtttgct ctgcagaata ctttacctgg gcacccaagt cttccttcca gcattcctgc tgctacagcc tatttgctga gtaaccaggg gttacagcag cgttgccagg caacgaggga cagcggtcct gttgaagagc catttgtcac actgagggga ctggttgaaa tgcaataaag aaatgatacc agcagctact catgtcttcg ccattgctaa gaacgtcgtt ggtattacct tactctgaga acgtgtctgc agtttccaga aaatggagta tcgcaacatc acttaaagta ccctgcttca aagtattgct ggcaagtggc gtgggcctga ttatttattt agaaatgctt tatcaggagg agaatgcttt tttgtaaaca tgaattgccc agttctttca ttgggctctg gcttcttgtt tcaggtcatt gaaatgttga tctttgccta ttttgcttca atatccttga ctgagtcacg aggtcttttc ccaaggctgg agaacgtggg agctttcaag aaagtttcca tcgtgccaac ccaagcagta tgtggactcc cagaccgaag cactttttgt cacagctctg ctgctgctga aagtattcag ttctgtaccc agcggttttg tattcaggat tgcccataca gatcttcaca ccctacctac actgcccttt tctcagcagg cctcagtagc tgcatcacac cagacaagaa tgatctgcat cctaacgccc atagcaattc tgcaagtttt atttttggaa atcacaagag ctgcttttct tctcctcctt ctccaaagct gatggcatca tttaccttag ctgtatggct gaaacctgag caacaaggtg taatgtgtgt tatagaaaag acagtagatg ggcagattgt gttcaaactt acaatatctg agaaagagac catgttttat tatcgcacag taaatggttt gcaacctcca ataaaagtaa tgacactggg gagaattctt gtgaagaaat ggattcatct tagtgtgcag gtgcatcaga caaaaatcag cttctttatc aatggcgtgg agaaggatca tacacctttc aatgcaagaa ctctaagtgg ttcaattaca gattttgcat ctggtactgt gcaaatagga cagagtttaa atggtttaga gcagtttgtc ggaagaatgc aagattttcg attataccaa gtggcactta caaacagaga gattctggaa gtcttctctg gagatcttct cagattgcat gcccaatcac attgccgttg ccctggcagc cacccgcggg tccacccttt ggcacagcgg tactgcattc ctaatgatgc aggagacaca gctgataata gagtgtcacg gttgaatcct gaagcccatc ctctctcttt tgtcaatgat aatgatgttg gtacttcatg ggtttcaaat gtgtttacaa acattacaca gcttaatcaa ggagtgacta tttcagttga tttggaaaat ggacagtatc aggtgtttta tattatcatt cagttcttta gtccacaacc aacggaaata aggattcaaa ggaagaagga aaatagttta gattgggagg actggcaata ttttgccagg aattgtggtg cttttggaat gaaaaacaat ggagatttgg aaaaacctga ttctgtcaac tgtcttcagc tttccaattt tactccatat tcccgtggca atgtcacatt tagcatcctg acacctggac caaattatcg tcctggatac aataacttct ataatacccc atctcttcaa gagttcgtaa aagccacgca aataaggttt cattttcatg ggcagtacta tacaactgag actgctgtta acctcagaca cagatattat gcagtggacg aaatcaccat tagtgggaga tgtcagtgcc atggtcatgc cgataactgc gacacaacaa gccagccata tagatgcctc tgctcccagg agagcttcac tgaaggactt cattgtgatc gctgcttgcc tctttataat gacaagcctt tccgccaagg tgatcaagtt tacgctttca attgtaaacc ttgtcaatgc aacagccatt ccaaaagctg ccattacaac atctctgtag acccatttcc ttttgagcac ttcagagggg gaggaggagt ttgtgatgat tgtgagcata acactacagg aaggaactgt gagctgtgca aggattactt tttccgacaa gttggtgcag atccttcggc catagatgtt tgcaaaccct gtgactgtga tacagttggc actagaaatg gtagcattct ttgtgatcag attggaggac agtgtaattg taagagacac gtgtctggca ggcagtgcaa tcagtgccag aatggattct acaatctaca agagttggat cctgatggct gcagtccctg taactgcaat acctctggga cagtggatgg agatattacc tgtcaccaaa attcaggcca gtgcaagtgc aaagcaaacg ttattgggct taggtgtgat cattgcaatt ttggatttaa atttctccga agctttaatg atgttggatg tgagccctgc cagtgtaacc tccatggctc agtgaacaaa ttctgcaatc ctcactctgg gcagtgtgag tgcaaaaaag aagccaaagg acttcagtgt gacacctgca gagaaaactt ttatgggtta gatgtcacca attgtaaggc ctgtgactgt gacacagctg gatccctccc tgggactgtc tgtaatgcta agacagggca gtgcatctgc aagcccaatg ttgaagggag acagtgcaat aaatgtttgg agggaaactt ctacctacgg caaaataatt ctttcctctg tctgccttgc aactgtgata agactgggac aataaatggc tctctgctgt gtaacaaatc aacaggacaa tgtccttgca aattaggggt aacaggtctt cgctgtaatc agtgtgagcc tcacaggtac aatttgacca ttgacaattt tcaacactgc cagatgtgtg agtgtgattc cttggggaca ttacctggga ccatttgtga cccaatcagt ggccagtgcc tgtgtgtgcc taatcgtcaa ggaagaaggt gtaatcagtg tcaaccaggt ttttatattt ctccaggcaa tgccactggc tgcctgccat gctcatgcca tacaactggt gcagttaatc acatctgtaa tagcctgact ggtcagtgtg tttgccaaga tgcttccatt gctgggcaac gttgtgacca atgcaaagac cattactttg gatttgatcc tcagactgga agatgtcagc cttgtaattg tcatctctca ggagccttga atgaaacctg tcacttggtc acaggccagt gtttctgtaa acaatttgtc actggctcaa agtgtgatgc ttgtgttccc agtgcaagcc acttggatgt caacaatcta ttgggttgca gcaaaactcc attccagcaa cctccgccca gaggacaagt tcaaagttct tctgctatca atctctcctg gagtccacct gattctccaa atgcccactg gcttacttac agtttactca gggatggttt tgaaatctac acaacagagg atcaataccc atacagtatt caatacttct tagacacaga cctgttacca tataccaaat attcctatta cattgagacc accaatgtgc atggttcaac aaggagtgta gctgtcactt acaagacaaa accaggggtc ccagagggaa acttgacttt aagttatatc attcctattg gctcagactc tgtgacactt acctggacaa cactctcaaa tcaatctggt cccatagaga aatatatttt gtcctgtgcc cctttggctg gtggtcagcc atgtgtttcc tacgaaggtc atgaaacctc agctaccatc tggaatctgg ttccatttgc caagtacgat ttttctgtac aggcgtgtac tagcgggggc tgtttacaca gcttgcccat tacagtgacc acagcccagg cccctcccca aagactaagt ccacctaaga tgcagaaaat cagttctaca gaacttcatg tagaatggtc tccaccagcg gaactaaatg gaataattat aagatatgaa ctatacatga gaagactgag atctactaaa gaaaccacat ctgaggaaag tcgagttttt cagagcagtg gttggctcag tcctcattca tttgtagaat cggccaatga aaatgcatta aaacctcctc aaacaatgac aaccatcact ggcttggagc catacaccaa gtatgagttc agagtcttag ctgtgaatat ggctggaagt gtgtcttctg cctgggtctc agaaagaacg ggagaatcag cacctgtatt catgatccct ccttcagtct ttcccctctc ttcgtactct ctcaatatct cctgggagaa gccagcagat aatgttacaa gaggaaaagt tgtggggtat gacatcaata tgctttctga acaatcacct caacagtcta ttcccatggc gttttcacag ctgttgcaca ctgctaaatc ccaagaacta tcttacactg tagaaggact gaaaccttat aggatatatg agtttactat tactctctgc aattcagttg gttgtgtgac cagtgcttcg ggagcaggac aaactttagc agcagcacca gcacaactga ggccacctct ggttaaagga atcaacagca caacaatcca tcttaggtgg tttccacctg aagaactgaa tggaccctct cctatatatc agctggaaag gagagagtca tctctaccag ctctgatgac cacgatgatg aaaggaatcc gtttcatagg aaatgggtat tgtaaatttc ccagctccac tcacccagtc aatacagact tcactggtaa gtgtgtttga cattgcttta tttaggagac acgaagctcc aaaatgtttt ctatattttc atatcccttt acaatgaatt tttattatac ctacttagag aaatactaat tcagcccttt gatagctttt gcctgattgt ttcagcatgt ccatcttttt agaattctgg ggaaaaaagt caggtaagtg aaggaaagga aaaataaaag atgaagatga agaagcagcc ttattggatc aaagtatgtg ctttgtattt gtctttttgt gaagtatgtg ccaggacatg tttcttgaaa tattattcac tgtgttctct gagcaaatga gtttgcaaaa tgccctcatg ctattggaga ttctcagtat gcaccccgtt actgaaactc caaaaagcat tgtaagaaag ctattcaact ttgcttagct aatcatgcct aacagatatt tgatgtaatg ttttcttttt ctttctcttg ctgtttcctt cttctttttt tcactgtgac aacttaatat ctcatgttct atgaagaaca ttgtggggaa aactaatccc agggaaaaga taacttctct aagccaggac tatggtaaag caagtgaggc tcttgtttcg gtcacaaaat ttaaaggcac taaaaaactc agtgttaatg taaattttaa tgcaatattt ttaaaaatga aaatcaatgt gaaagcacta taaaaatatt atcaaaagct taaataaaga cagattgaac tctgtaccag cacaatcctg cctcactggc cttaccctcc tcctggcctt actagtaccg caatattttg gaagtcccat gacctctgtg acttacagct tctaatagca tgatttcaat atagctgtaa aaaaactcta cttatggtac accatttttc caatttttaa aaaaatttac aaagtataag atatatatta ttatgtaaac tcataaagat gttcatttaa tcatccatga gaaagtcatt ttggagcaaa tagctagtct ttaaaatatt gcatatgtga agacaatgaa atggaattcg agctataaaa atttgtattg ttttattttt acttaaaata gtaaatagtt tgcttttcat tgagactggc tgctgatgca ccttggtaat gaatcatgat tatattctaa ctgagatata ttgagattaa tgcatgatta actactctct cagtacatca aaatcattgc agagtattag aaattgaacc attgagctaa aaatgctcaa cttctgcttt atattcttaa aatggcaaaa aa (SEQ ID NO:3), or a nucleotide sequence which has at least 80%, 85%, 87%, 90%, 92%, 93%, 94%, 95%, 98%, 99% or more nucleic acid sequence identity thereto, or a nucleotide sequence that encodes MNCPVLSLGSGFLFQVIEMLIFAYFASISLTESRGLFPRLENVG AFKKVSIVPTQAVCGLPDRSTFCHSSAAAESIQFCTQRFCIQDCPYRSSHPTYTALFS AGLSSCITPDKNDLHPNAHSNSASFIFGNHKSCFSSPPSPKLMASFTLAVWLKPEQQG VMCVIEKTVDGQIVFKLTISEKETMFYYRTVNGLQPPIKVMTLGRILVKKWIHLSVQV HQTKISFFINGVEKDHTPFNARTLSGSITDFASGTVQIGQSLNGLEQFVGRMQDFRLY QVALTNREILEVFSGDLLRLHAQSHCRCPGSHPRVHPLAQRYCIPNDAGDTADNRVSR LNPEAHPLSFVNDNDVGTSWVSNVFTNITQLNQGVTISVDLENGQYQVFYIIIQFFSP QPTEIRIQRKKENSLDWEDWQYFARNCGAFGMKNNGDLEKPDSVNCLQLSNFTPYSRG NVTFSILTPGPNYRPGYNNFYNTPSLQEFVKATQIRFHFHGQYYTTETAVNLRHRYYA VDEITISGRCQCHGHADNCDTTSQPYRCLCSQESFTEGLHCDRCLPLYNDKPFRQGDQ VYAFNCKPCQCNSHSKSCHYNISVDPFPFEHFRGGGGVCDDCEHNTTGRNCELCKDYF FRQVGADPSAIDVCKPCDCDTVGTRNGSILCDQIGGQCNCKRHVSGRQCNQCQNGFYN LQELDPDGCSPCNCNTSGTVDGDITCHQNSGQCKCKANVIGLRCDHCNFGFKFLRSFN DVGCEPCQCNLHGSVNKFCNPHSGQCECKKEAKGLQCDTCRENFYGLDVTNCKACDCD TAGSLPGTVCNAKTGQCICKPNVEGRQCNKCLEGNFYLRQNNSFLCLPCNCDKTGTIN GSLLCNKSTGQCPCKLGVTGLRCNQCEPHRYNLTIDNFQHCQMCECDSLGTLPGTICD PISGQCLCVPNRQGRRCNQCQPGFYISPGNATGCLPCSCHTTGAVNHICNSLTGQCVC QDASIAGQRCDQCKDHYFGFDPQTGRCQPCNCHLSGALNETCHLVTGQCFCKQFVTGS KCDACVPSASHLDVNNLLGCSKTPFQQPPPRGQVQSSSAINLSWSPPDSPNAHWLTYS LLRDGFEIYTTEDQYPYSIQYFLDTDLLPYTKYSYYIETTNVHGSTRSVAVTYKTKPG VPEGNLTLSYIIPIGSDSVTLTWTTLSNQSGPIEKYILSCAPLAGGQPCVSYEGHETS ATIWNLVPFAKYDFSVQACTSGGCLHSLPITVTTAQAPPQRLSPPKMQKISSTELHVE WSPPAELNGIIIRYELYMRRLRSTKETTSEESRVFQSSGWLSPHSFVESANENALKPP QTMTTITGLEPYTKYEFRVLAVNMAGSVSSAWVSERTGESAPVFMIPPSVFPLSSYSL NISWEKPADNVTRGKVVGYDINMLSEQSPQQSIPMAFSQLLHTAKSQELSYTVEGLKP YRIYEFTITLCNSVGCVTSASGAGQTLAAAPAQLRPPLVKGINSTTIHLRWFPPEELN GPSPIYQLERRESSLPALMTTMMKGIRFIGNGYCKFPSSTHPVNTDFTGKCV (SEQ ID NO:4), or a polypeptide sequence which has at least 80%, 85%, 87%, 90%, 92%, 93%, 94%, 95%, 98%, 99% or more amino acid sequence identity thereto. In one embodiment, the gene is ATP binding cassette subfamily A member 4 (ABCA4), and the nucleotide sequence comprises ggacacagcg tccggagcca gaggcgctct taacggcgtt tatgtccttt gctgtctgag gggcctcagc tctgaccaat ctggtcttcg tgtggtcatt agcatgggct tcgtgagaca gatacagctt ttgctctgga agaactggac cctgcggaaa aggcaaaaga ttcgctttgt ggtggaactc gtgtggcctt tatctttatt tctggtcttg atctggttaa ggaatgccaa cccactctac agccatcatg aatgccattt ccccaacaag gcgatgccct cagcaggaat gctgccgtgg ctccagggga tcttctgcaa tgtgaacaat ccctgttttc aaagccccac cccaggagaa tctcctggaa ttgtgtcaaa ctataacaac tccatcttgg caagggtata tcgagatttt caagaactcc tcatgaatgc accagagagc cagcaccttg gccgtatttg gacagagcta cacatcttgt cccaattcat ggacaccctc cggactcacc cggagagaat tgcaggaaga ggaatacgaa taagggatat cttgaaagat gaagaaacac tgacactatt tctcattaaa aacatcggcc tgtctgactc agtggtctac cttctgatca actctcaagt ccgtccagag cagttcgctc atggagtccc ggacctggcg ctgaaggaca tcgcctgcag cgaggccctc ctggagcgct tcatcatctt cagccagaga cgcggggcaa agacggtgcg ctatgccctg tgctccctct cccagggcac cctacagtgg atagaagaca ctctgtatgc caacgtggac ttcttcaagc tcttccgtgt gcttcccaca ctcctagaca gccgttctca aggtatcaat ctgagatctt ggggaggaat attatctgat atgtcaccaa gaattcaaga gtttatccat cggccgagta tgcaggactt gctgtgggtg accaggcccc tcatgcagaa tggtggtcca gagaccttta caaagctgat gggcatcctg tctgacctcc tgtgtggcta ccccgaggga ggtggctctc gggtgctctc cttcaactgg tatgaagaca ataactataa ggcctttctg gggattgact ccacaaggaa ggatcctatc tattcttatg acagaagaac aacatccttt tgtaatgcat tgatccagag cctggagtca aatcctttaa ccaaaatcgc ttggagggcg gcaaagcctt tgctgatggg aaaaatcctg tacactcctg attcacctgc agcacgaagg atactgaaga atgccaactc aacttttgaa gaactggaac acgttaggaa gttggtcaaa gcctgggaag aagtagggcc ccagatctgg tacttctttg acaacagcac acagatgaac atgatcagag ataccctggg gaacccaaca gtaaaagact ttttgaatag gcagcttggt gaagaaggta ttactgctga agccatccta aacttcctct acaagggccc tcgggaaagc caggctgacg acatggccaa cttcgactgg agggacatat ttaacatcac tgatcgcacc ctccgcctgg tcaatcaata cctggagtgc ttggtcctgg ataagtttga aagctacaat gatgaaactc agctcaccca acgtgccctc tctctactgg aggaaaacat gttctgggcc ggagtggtat tccctgacat gtatccctgg accagctctc taccacccca cgtgaagtat aagatccgaa tggacataga cgtggtggag aaaaccaata agattaaaga caggtattgg gattctggtc ccagagctga tcccgtggaa gatttccggt acatctgggg cgggtttgcc tatctgcagg acatggttga acaggggatc acaaggagcc aggtgcaggc ggaggctcca gttggaatct acctccagca gatgccctac ccctgcttcg tggacgattc tttcatgatc atcctgaacc gctgtttccc tatcttcatg gtgctggcat ggatctactc tgtctccatg actgtgaaga gcatcgtctt ggagaaggag ttgcgactga aggagacctt gaaaaatcag ggtgtctcca atgcagtgat ttggtgtacc tggttcctgg acagcttctc catcatgtcg atgagcatct tcctcctgac gatattcatc atgcatggaa gaatcctaca ttacagcgac ccattcatcc tcttcctgtt cttgttggct ttctccactg ccaccatcat gctgtgcttt ctgctcagca ccttcttctc caaggccagt ctggcagcag cctgtagtgg tgtcatctat ttcaccctct acctgccaca catcctgtgc ttcgcctggc aggaccgcat gaccgctgag ctgaagaagg ctgtgagctt actgtctccg gtggcatttg gatttggcac tgagtacctg gttcgctttg aagagcaagg cctggggctg cagtggagca acatcgggaa cagtcccacg gaaggggacg aattcagctt cctgctgtcc atgcagatga tgctccttga tgctgctgtc tatggcttac tcgcttggta ccttgatcag gtgtttccag gagactatgg aaccccactt ccttggtact ttcttctaca agagtcgtat tggcttggcg gtgaagggtg ttcaaccaga gaagaaagag ccctggaaaa gaccgagccc ctaacagagg aaacggagga tccagagcac ccagaaggaa tacacgactc cttctttgaa cgtgagcatc cagggtgggt tcctggggta tgcgtgaaga atctggtaaa gatttttgag ccctgtggcc ggccagctgt ggaccgtctg aacatcacct tctacgagaa ccagatcacc gcattcctgg gccacaatgg agctgggaaa accaccacct tgtccatcct gacgggtctg ttgccaccaa cctctgggac tgtgctcgtt gggggaaggg acattgaaac cagcctggat gcagtccggc agagccttgg catgtgtcca cagcacaaca tcctgttcca ccacctcacg gtggctgagc acatgctgtt ctatgcccag ctgaaaggaa agtcccagga ggaggcccag ctggagatgg aagccatgtt ggaggacaca ggcctccacc acaagcggaa tgaagaggct caggacctat caggtggcat gcagagaaag ctgtcggttg ccattgcctt tgtgggagat gccaaggtgg tgattctgga cgaacccacc tctggggtgg acccttactc gagacgctca atctgggatc tgctcctgaa gtatcgctca ggcagaacca tcatcatgtc cactcaccac atggacgagg ccgacctcct tggggaccgc attgccatca ttgcccaggg aaggctctac tgctcaggca ccccactctt cctgaagaac tgctttggca caggcttgta cttaaccttg gtgcgcaaga tgaaaaacat ccagagccaa aggaaaggca gtgaggggac ctgcagctgc tcgtctaagg gtttctccac cacgtgtcca gcccacgtcg atgacctaac tccagaacaa gtcctggatg gggatgtaaa tgagctgatg gatgtagttc tccaccatgt tccagaggca aagctggtgg agtgcattgg tcaagaactt atcttccttc ttccaaataa gaacttcaag cacagagcat atgccagcct tttcagagag ctggaggaga cgctggctga ccttggtctc agcagttttg gaatttctga cactcccctg gaagagattt ttctgaaggt cacggaggat tctgattcag gacctctgtt tgcgggtggc gctcagcaga aaagagaaaa cgtcaacccc cgacacccct gcttgggtcc cagagagaag gctggacaga caccccagga ctccaatgtc tgctccccag gggcgccggc tgctcaccca gagggccagc ctcccccaga gccagagtgc ccaggcccgc agctcaacac ggggacacag ctggtcctcc agcatgtgca ggcgctgctg gtcaagagat tccaacacac catccgcagc cacaaggact tcctggcgca gatcgtgctc ccggctacct ttgtgttttt ggctctgatg ctttctattg ttatccctcc ttttggcgaa taccccgctt tgacccttca cccctggata tatgggcagc agtacacctt cttcagcatg gatgaaccag gcagtgagca gttcacggta cttgcagacg tcctcctgaa taagccaggc tttggcaacc gctgcctgaa ggaagggtgg cttccggagt acccctgtgg caactcaaca ccctggaaga ctccttctgt gtccccaaac atcacccagc tgttccagaa gcagaaatgg acacaggtca acccttcacc atcctgcagg tgcagcacca gggagaagct caccatgctg ccagagtgcc ccgagggtgc cgggggcctc ccgccccccc agagaacaca gcgcagcacg gaaattctac aagacctgac ggacaggaac atctccgact tcttggtaaa aacgtatcct gctcttataa gaagcagctt aaagagcaaa ttctgggtca atgaacagag gtatggagga atttccattg gaggaaagct cccagtcgtc cccatcacgg gggaagcact tgttgggttt ttaagcgacc ttggccggat catgaatgtg agcgggggcc ctatcactag agaggcctct aaagaaatac ctgatttcct taaacatcta gaaactgaag acaacattaa ggtgtggttt aataacaaag gctggcatgc cctggtcagc tttctcaatg tggcccacaa cgccatctta cgggccagcc tgcctaagga caggagcccc gaggagtatg gaatcaccgt cattagccaa cccctgaacc tgaccaagga gcagctctca gagattacag tgctgaccac ttcagtggat gctgtggttg ccatctgcgt gattttctcc atgtccttcg tcccagccag ctttgtcctt tatttgatcc aggagcgggt gaacaaatcc aagcacctcc agtttatcag tggagtgagc cccaccacct actgggtgac caacttcctc tgggacatca tgaattattc cgtgagtgct gggctggtgg tgggcatctt catcgggttt cagaagaaag cctacacttc tccagaaaac cttcctgccc ttgtggcact gctcctgctg tatggatggg cggtcattcc catgatgtac ccagcatcct tcctgtttga tgtccccagc acagcctatg tggctttatc ttgtgctaat ctgttcatcg gcatcaacag cagtgctatt accttcatct tggaattatt tgagaataac cggacgctgc tcaggttcaa cgccgtgctg aggaagctgc tcattgtctt cccccacttc tgcctgggcc ggggcctcat tgaccttgca ctgagccagg ctgtgacaga tgtctatgcc cggtttggtg aggagcactc tgcaaatccg ttccactggg acctgattgg gaagaacctg tttgccatgg tggtggaagg ggtggtgtac ttcctcctga ccctgctggt ccagcgccac ttcttcctct cccaatggat tgccgagccc actaaggagc ccattgttga tgaagatgat gatgtggctg aagaaagaca aagaattatt actggtggaa ataaaactga catcttaagg ctacatgaac taaccaagat ttatccaggc acctccagcc cagcagtgga caggctgtgt gtcggagttc gccctggaga gtgctttggc ctcctgggag tgaatggtgc cggcaaaaca accacattca agatgctcac tggggacacc acagtgacct caggggatgc caccgtagca ggcaagagta ttttaaccaa tatttctgaa gtccatcaaa atatgggcta ctgtcctcag tttgatgcaa ttgatgagct gctcacagga cgagaacatc tttaccttta tgcccggctt cgaggtgtac cagcagaaga aatcgaaaag gttgcaaact ggagtattaa gagcctgggc ctgactgtct acgccgactg cctggctggc acgtacagtg ggggcaacaa gcggaaactc tccacagcca tcgcactcat tggctgccca ccgctggtgc tgctggatga gcccaccaca gggatggacc cccaggcacg ccgcatgctg tggaacgtca tcgtgagcat catcagagaa gggagggctg tggtcctcac atcccacagc atggaagaat gtgaggcact gtgtacccgg ctggccatca tggtaaaggg cgcctttcga tgtatgggca ccattcagca tctcaagtcc aaatttggag atggctatat cgtcacaatg aagatcaaat ccccgaagga cgacctgctt cctgacctga accctgtgga gcagttcttc caggggaact tcccaggcag tgtgcagagg gagaggcact acaacatgct ccagttccag gtctcctcct cctccctggc gaggatcttc cagctcctcc tctcccacaa ggacagcctg ctcatcgagg agtactcagt cacacagacc acactggacc aggtgtttgt aaattttgct aaacagcaga ctgaaagtca tgacctccct ctgcaccctc gagctgctgg agccagtcga caagcccagg actgatcttt cacaccgctc gttcctgcag ccagaaagga actctgggca gctggaggcg caggagcctg tgcccatatg gtcatccaaa tggactggcc agcgtaaatg accccactgc agcagaaaac aaacacacga ggagcatgca gcgaattcag aaagaggtct ttcagaagga aaccgaaact gacttgctca cctggaacac ctgatggtga aaccaaacaa atacaaaatc cttctccaga ccccagaact agaaaccccg ggccatccca ctagcagctt tggcctccat attgctctca tttcaagcag atctgctttt ctgcatgttt gtctgtgtgt ctgcgttgtg tgtgattttc atggaaaaat aaaatgcaaa tgcactcatc acaaacta (SEQ ID NO:5) or a nucleotide sequence which has at least 80%, 85%, 87%, 90%, 92%, 93%, 94%, 95%, 98%, 99% or more nucleic acid sequence identity thereto, or a nucleotide sequence that encodes MGFVRQIQLLLWKNWTLRKRQKIRFVVELVWPLSLFLVLIWLRN ANPLYSHHECHFPNKAMPSAGMLPWLQGIFCNVNNPCFQSPTPGESPGIVSNYNNSIL ARVYRDFQELLMNAPESQHLGRIWTELHILSQFMDTLRTHPERIAGRGIRIRDILKDE ETLTLFLIKNIGLSDSVVYLLINSQVRPEQFAHGVPDLALKDIACSEALLERFIIFSQ RRGAKTVRYALCSLSQGTLQWIEDTLYANVDFFKLFRVLPTLLDSRSQGINLRSWGGI LSDMSPRIQEFIHRPSMQDLLWVTRPLMQNGGPETFTKLMGILSDLLCGYPEGGGSRV LSFNWYEDNNYKAFLGIDSTRKDPIYSYDRRTTSFCNALIQSLESNPLTKIAWRAAKP LLMGKILYTPDSPAARRILKNANSTFEELEHVRKLVKAWEEVGPQIWYFFDNSTQMNM IRDTLGNPTVKDFLNRQLGEEGITAEAILNFLYKGPRESQADDMANFDWRDIFNITDR TLRLVNQYLECLVLDKFESYNDETQLTQRALSLLEENMFWAGVVFPDMYPWTSSLPPH VKYKIRMDIDVVEKTNKIKDRYWDSGPRADPVEDFRYIWGGFAYLQDMVEQGITRSQV QAEAPVGIYLQQMPYPCFVDDSFMIILNRCFPIFMVLAWIYSVSMTVKSIVLEKELRL KETLKNQGVSNAVIWCTWFLDSFSIMSMSIFLLTIFIMHGRILHYSDPFILFLFLLAF STATIMLCFLLSTFFSKASLAAACSGVIYFTLYLPHILCFAWQDRMTAELKKAVSLLS PVAFGFGTEYLVRFEEQGLGLQWSNIGNSPTEGDEFSFLLSMQMMLLDAAVYGLLAWY LDQVFPGDYGTPLPWYFLLQESYWLGGEGCSTREERALEKTEPLTEETEDPEHPEGIH DSFFEREHPGWVPGVCVKNLVKIFEPCGRPAVDRLNITFYENQITAFLGHNGAGKTTT LSILTGLLPPTSGTVLVGGRDIETSLDAVRQSLGMCPQHNILFHHLTVAEHMLFYAQL KGKSQEEAQLEMEAMLEDTGLHHKRNEEAQDLSGGMQRKLSVAIAFVGDAKVVILDEP TSGVDPYSRRSIWDLLLKYRSGRTIIMSTHHMDEADLLGDRIAIIAQGRLYCSGTPLF LKNCFGTGLYLTLVRKMKNIQSQRKGSEGTCSCSSKGFSTTCPAHVDDLTPEQVLDGD VNELMDVVLHHVPEAKLVECIGQELIFLLPNKNFKHRAYASLFRELEETLADLGLSSF GISDTPLEEIFLKVTEDSDSGPLFAGGAQQKRENVNPRHPCLGPREKAGQTPQDSNVC SPGAPAAHPEGQPPPEPECPGPQLNTGTQLVLQHVQALLVKRFQHTIRSHKDFLAQIV LPATFVFLALMLSIVIPPFGEYPALTLHPWIYGQQYTFFSMDEPGSEQFTVLADVLLN KPGFGNRCLKEGWLPEYPCGNSTPWKTPSVSPNITQLFQKQKWTQVNPSPSCRCSTRE KLTMLPECPEGAGGLPPPQRTQRSTEILQDLTDRNISDFLVKTYPALIRSSLKSKFWV NEQRYGGISIGGKLPVVPITGEALVGFLSDLGRIMNVSGGPITREASKEIPDFLKHLE TEDNIKVWFNNKGWHALVSFLNVAHNAILRASLPKDRSPEEYGITVISQPLNLTKEQL SEITVLTTSVDAVVAICVIFSMSFVPASFVLYLIQERVNKSKHLQFISGVSPTTYWVT NFLWDIMNYSVSAGLVVGIFIGFQKKAYTSPENLPALVALLLLYGWAVIPMMYPASFL FDVPSTAYVALSCANLFIGINSSAITFILELFENNRTLLRFNAVLRKLLIVFPHFCLG RGLIDLALSQAVTDVYARFGEEHSANPFHWDLIGKNLFAMVVEGVVYFLLTLLVQRHF FLSQWIAEPTKEPIVDEDDDVAEERQRIITGGNKTDILRLHELTKIYPGTSSPAVDRL CVGVRPGECFGLLGVNGAGKTTTFKMLTGDTTVTSGDATVAGKSILTNISEVHQNMGY CPQFDAIDELLTGREHLYLYARLRGVPAEEIEKVANWSIKSLGLTVYADCLAGTYSGG NKRKLSTAIALIGCPPLVLLDEPTTGMDPQARRMLWNVIVSIIREGRAVVLTSHSMEE CEALCTRLAIMVKGAFRCMGTIQHLKSKFGDGYIVTMKIKSPKDDLLPDLNPVEQFFQ GNFPGSVQRERHYNMLQFQVSSSSLARIFQLLLSHKDSLLIEEYSVTQTTLDQVFVNF AKQQTESHDLPLHPRAAGASRQAQD (SEQ ID NO:6), or a polypeptide sequence which has at least 80%, 85%, 87%, 90%, 92%, 93%, 94%, 95%, 98%, 99% or more amino acid sequence identity thereto. In one embodiment, the gene is centrosomal protein 290 (CEP290), and the nucleotide sequence comprises), 1 attctggcct tggcggagtt ggggatggtg tcgcctagca gccgctgccg ctttggcttg 61 ctcgggacca tttggctgga cccagagtcc gcgtggaacc gcgataggga tctgtcaggg 121 cccgcggccg ggtccagctt ggtggttgcg gtagtgagag gcctccgctg gttgccaggc 181 ttggtctaga ggtggagcac agtgaaagaa ttcaagatgc cacctaatat aaactggaaa 241 gaaataatga aagttgaccc agatgacctg ccccgtcaag aagaactggc agataattta 301 ttgatttcct tatccaaggt ggaagtaaat gagctaaaaa gtgaaaagca agaaaatgtg 361 atacaccttt tcagaattac tcagtcacta atgaagatga aagctcaaga agtggagctg 421 gctttggaag aagtagaaaa agctggagaa gaacaagcaa aatttgaaaa tcaattaaaa 481 actaaagtaa tgaaactgga aaatgaactg gagatggctc agcagtctgc aggtggacga 541 gatactcggt ttttacgtaa tgaaatttgc caacttgaaa aacaattaga acaaaaagat 601 agagaattgg aggacatgga aaaggagttg gagaaagaga agaaagttaa tgagcaattg 661 gctcttcgaa atgaggaggc agaaaatgaa aacagcaaat taagaagaga gaacaaacgt 721 ctaaagaaaa agaatgaaca actttgtcag gatattattg actaccagaa acaaatagat 781 tcacagaaag aaacactttt atcaagaaga ggggaagaca gtgactaccg atcacagttg 841 tctaaaaaaa actatgagct tatccaatat cttgatgaaa ttcagacttt aacagaagct 901 aatgagaaaa ttgaagttca gaatcaagaa atgagaaaaa atttagaaga gtctgtacag 961 gaaatggaga agatgactga tgaatataat agaatgaaag ctattgtgca tcagacagat 1021 aatgtaatag atcagttaaa aaaagaaaac gatcattatc aacttcaagt gcaggagctt 1081 acagatcttc tgaaatcaaa aaatgaagaa gatgatccaa ttatggtagc tgtcaatgca 1141 aaagtagaag aatggaagct aattttgtct tctaaagatg atgaaattat tgagtatcag 1201 caaatgttac ataacctaag ggagaaactt aagaatgctc agcttgatgc tgataaaagt 1261 aatgttatgg ctctacagca gggtatacag gaacgagaca gtcaaattaa gatgctcacc 1321 gaacaagtag aacaatatac aaaagaaatg gaaaagaata cttgtattat tgaagatttg 1381 aaaaatgagc tccaaagaaa caaaggtgct tcaacccttt ctcaacagac tcatatgaaa 1441 attcagtcaa cgttagacat tttaaaagag aaaactaaag aggctgagag aacagctgaa 1501 ctggctgagg ctgatgctag ggaaaaggat aaagaattag ttgaggctct gaagaggtta 1561 aaagattatg aatcgggagt atatggttta gaagatgctg tcgttgaaat aaagaattgt 1621 aaaaaccaaa ttaaaataag agatcgagag attgaaatat taacaaagga aatcaataaa 1681 cttgaattga agatcagtga tttccttgat gaaaatgagg cacttagaga gcgtgtgggc 1741 cttgaaccaa agacaatgat tgatttaact gaatttagaa atagcaaaca cttaaaacag 1801 cagcagtaca gagctgaaaa ccagattctt ttgaaagaga ttgaaagtct agaggaagaa 1861 cgacttgatc tgaaaaaaaa aattcgtcaa atggctcaag aaagaggaaa aagaagtgca 1921 acttcaggat taaccactga ggacctgaac ctaactgaaa acatttctca aggagataga 1981 ataagtgaaa gaaaattgga tttattgagc ctcaaaaata tgagtgaagc acaatcaaag 2041 aatgaatttc tttcaagaga actaattgaa aaagaaagag atttagaaag gagtaggaca 2101 gtgatagcca aatttcagaa taaattaaaa gaattagttg aagaaaataa gcaacttgaa 2161 gaaggtatga aagaaatatt gcaagcaatt aaggaaatgc agaaagatcc tgatgttaaa 2221 ggaggagaaa catctctaat tatccctagc cttgaaagac tagttaatgc tatagaatca 2281 aagaatgcag aaggaatctt tgatgcgagt ctgcatttga aagcccaagt tgatcagctt 2341 accggaagaa atgaagaatt aagacaggag ctcagggaat ctcggaaaga ggctataaat 2401 tattcacagc agttggcaaa agctaattta aagatagacc atcttgaaaa agaaactagt 2461 cttttacgac aatcagaagg atcaaatgtt gtttttaaag gaattgactt acctgatggg 2521 atagcaccat ctagtgccag tatcattaat tctcagaatg aatatttaat acatttgtta 2581 caggaactag aaaataaaga aaaaaagtta aagaatttag aagattctct tgaagattac 2641 aacagaaaat ttgctgtaat tcgtcatcaa caaagtttgt tgtataaaga atacctaagt 2701 gaaaaggaga cctggaaaac agaatctaaa acaataaaag aggaaaagag aaaacttgag 2761 gatcaagtcc aacaagatgc tataaaagta aaagaatata ataatttgct caatgctctt 2821 cagatggatt cggatgaaat gaaaaaaata cttgcagaaa atagtaggaa aattactgtt 2881 ttgcaagtga atgaaaaatc acttataagg caatatacaa ccttagtaga attggagcga 2941 caacttagaa aagaaaatga gaagcaaaag aatgaattgt tgtcaatgga ggctgaagtt 3001 tgtgaaaaaa ttgggtgttt gcaaagattt aaggaaatgg ccattttcaa gattgcagct 3061 ctccaaaaag ttgtagataa tagtgtttct ttgtctgaac tagaactggc taataaacag 3121 tacaatgaac tgactgctaa gtacagggac atcttgcaaa aagataatat gcttgttcaa 3181 agaacaagta acttggaaca cctggagtgt gaaaacatct ccttaaaaga acaagtggag 3241 tctataaata aagaactgga gattaccaag gaaaaacttc acactattga acaagcctgg 3301 gaacaggaaa ctaaattagg taatgaatct agcatggata aggcaaagaa atcaataacc 3361 aacagtgaca ttgtttccat ttcaaaaaaa ataactatgc tggaaatgaa ggaattaaat 3421 gaaaggcagc gggctgaaca ttgtcaaaaa atgtatgaac acttacggac ttcgttaaag 3481 caaatggagg aacgtaattt tgaattggaa accaaatttg ctgagcttac caaaatcaat 3541 ttggatgcac agaaggtgga acagatgtta agagatgaat tagctgatag tgtgagcaag 3601 gcagtaagtg atgctgatag gcaacggatt ctagaattag agaagaatga aatggaacta 3661 aaagttgaag tgtcaaaact gagagagatt tctgatattg ccagaagaca agttgaaatt 3721 ttgaatgcac aacaacaatc tagggacaag gaagtagagt ccctcagaat gcaactgcta 3781 gactatcagg cacagtctga tgaaaagtcg ctcattgcca agttgcacca acataatgtc 3841 tctcttcaac tgagtgaggc tactgctctt ggtaagttgg agtcaattac atctaaactg 3901 cagaagatgg aggcctacaa cttgcgctta gagcagaaac ttgatgaaaa agaacaggct 3961 ctctattatg ctcgtttgga gggaagaaac agagcaaaac atctgcgcca aacaattcag 4021 tctctacgac gacagtttag tggagcttta cccttggcac aacaggaaaa gttctccaaa 4081 acaatgattc aactacaaaa tgacaaactt aagataatgc aagaaatgaa aaattctcaa 4141 caagaacata gaaatatgga gaacaaaaca ttggagatgg aattaaaatt aaagggcctg 4201 gaagagttaa taagcacttt aaaggatacc aaaggagccc aaaaggtaat caactggcat 4261 atgaaaatag aagaacttcg tcttcaagaa cttaaactaa atcgggaatt agtcaaggat 4321 aaagaagaaa taaaatattt gaataacata atttctgaat atgaacgtac aatcagcagt 4381 cttgaagaag aaattgtgca acagaacaag tttcatgaag aaagacaaat ggcctgggat 4441 caaagagaag ttgacctgga acgccaacta gacatttttg accgtcagca aaatgaaata 4501 ctaaatgcgg cacaaaagtt tgaagaagct acaggatcaa tccctgaccc tagtttgccc 4561 cttccaaatc aacttgagat cgctctaagg aaaattaagg agaacattcg aataattcta 4621 gaaacacggg caacttgcaa atcactagaa gagaaactaa aagagaaaga atctgcttta 4681 aggttagcag aacaaaatat actgtcaaga gacaaagtaa tcaatgaact gaggcttcga 4741 ttgcctgcca ctgcagaaag agaaaagctc atagctgagc taggcagaaa agagatggaa 4801 ccaaaatctc accacacatt gaaaattgct catcaaacca ttgcaaacat gcaagcaagg 4861 ttaaatcaaa aagaagaagt attaaagaag tatcaacgtc ttctagaaaa agccagagag 4921 gagcaaagag aaattgtgaa gaaacatgag gaagaccttc atattcttca tcacagatta 4981 gaactacagg ctgatagttc actaaataaa ttcaaacaaa cggcttggga tttaatgaaa 5041 cagtctccca ctccagttcc taccaacaag cattttattc gtctggctga gatggaacag 5101 acagtagcag aacaagatga ctctctttcc tcactcttgg tcaaactaaa gaaagtatca 5161 caagatttgg agagacaaag agaaatcact gaattaaaag taaaagaatt tgaaaatatc 5221 aaattacagc ttcaagaaaa ccatgaagat gaagtgaaaa aagtaaaagc ggaagtagag 5281 gatttaaagt atcttctgga ccagtcacaa aaggagtcac agtgtttaaa atctgaactt 5341 caggctcaaa aagaagcaaa ttcaagagct ccaacaacta caatgagaaa tctagtagaa 5401 cggctaaaga gccaattagc cttgaaggag aaacaacaga aagcacttag tcgggcactt 5461 ttagaactcc gggcagaaat gacagcagct gctgaagaac gtattatttc tgcaacttct 5521 caaaaagagg cccatctcaa tgttcaacaa atcgttgatc gacatactag agagctaaag 5581 acacaagttg aagatttaaa tgaaaatctt ttaaaattga aagaagcact taaaacaagt 5641 aaaaacagag aaaactcact aactgataat ttgaatgact taaataatga actgcaaaag 5701 aaacaaaaag cctataataa aatacttaga gagaaagagg aaattgatca agagaatgat 5761 gaactgaaaa ggcaaattaa aagactaacc agtggattac agggcaaacc cctgacagat 5821 aataaacaaa gtctaattga agaactccaa aggaaagtta aaaaactaga gaaccaatta 5881 gagggaaagg tggaggaagt agacctaaaa cctatgaaag aaaagaatgc taaagaagaa 5941 ttaattaggt gggaagaagg taaaaagtgg caagccaaaa tagaaggaat tcgaaacaag 6001 ttaaaagaga aagaggggga agtctttact ttaacaaagc agttgaatac tttgaaggat 6061 ctttttgcca aagccgataa agagaaactt actttgcaga ggaaactaaa aacaactggc 6121 atgactgttg atcaggtttt gggaatacga gctttggagt cagaaaaaga attggaagaa 6181 ttaaaaaaga gaaatcttga cttagaaaat gatatattgt atatgagggc ccaccaagct 6241 cttcctcgag attctgttgt agaagattta catttacaaa atagatacct ccaagaaaaa 6301 cttcatgctt tagaaaaaca gttttcaaag gatacatatt ctaagccttc aatttcagga 6361 atagagtcag atgatcattg tcagagagaa caggagcttc agaaggaaaa cttgaagttg 6421 tcatctgaaa atattgaact gaaatttcag cttgaacaag caaataaaga tttgccaaga 6481 ttaaagaatc aagtcagaga tttgaaggaa atgtgtgaat ttcttaagaa agaaaaagca 6541 gaagttcagc ggaaacttgg ccatgttaga gggtctggta gaagtggaaa gacaatccca 6601 gaactggaaa aaaccattgg tttaatgaaa aaagtagttg aaaaagtcca gagagaaaat 6661 gaacagttga aaaaagcatc aggaatattg actagtgaaa aaatggctaa tattgagcag 6721 gaaaatgaaa aattgaaggc tgaattagaa aaacttaaag ctcatcttgg gcatcagttg 6781 agcatgcact atgaatccaa gaccaaaggc acagaaaaaa ttattgctga aaatgaaagg 6841 cttcgtaaag aacttaaaaa agaaactgat gctgcagaga aattacggat agcaaagaat 6901 aatttagaga tattaaatga gaagatgaca gttcaactag aagagactgg taagagattg 6961 cagtttgcag aaagcagagg tccacagctt gaaggtgctg acagtaagag ctggaaatcc 7021 attgtggtta caagaatgta tgaaaccaag ttaaaagaat tggaaactga tattgccaaa 7081 aaaaatcaaa gcattactga ccttaaacag cttgtaaaag aagcaacaga gagagaacaa 7141 aaagttaaca aatacaatga agaccttgaa caacagatta agattcttaa acatgttcct 7201 gaaggtgctg agacagagca aggccttaaa cgggagcttc aagttcttag attagctaat 7261 catcagctgg ataaagagaa agcagaatta atccatcaga tagaagctaa caaggaccaa 7321 agtggagctg aaagcaccat acctgatgct gatcaactaa aggaaaaaat aaaagatcta 7381 gagacacagc tcaaaatgtc agatctagaa aagcagcatt tgaaggagga aataaagaag 7441 ctgaaaaaag aactggaaaa ttttgatcct tcattttttg aagaaattga agatcttaag 7501 tataattaca aggaagaagt gaagaagaat attctcttag aagagaaggt aaaaaaactt 7561 tcagaacaat tgggagttga attaactagc cctgttgctg cttctgaaga gtttgaagat 7621 gaagaagaaa gtcctgttaa tttccccatt tactaaaggt cacctataaa ctttgtttca 7681 tttaactatt tattaacttt ataagttaaa tatacttgga aataagcagt tctccgaact 7741 gtagtatttc cttctcacta ccttgtacct ttatacttag attggaattc ttaataaata 7801 aaattatatg aaattttcaa ctta (SEQ ID NO:7), or a nucleotide sequence which has at least 80%, 85%, 87%, 90%, 92%, 93%, 94%, 95%, 98%, 99% or more nucleic acid sequence identity thereto, or a nucleotide sequence that encodes a polypeptide having MPPNINWKEIMKVDPDDLPRQEELADNLLISLSKVEVNELKSEK QENVIHLFRITQSLMKMKAQEVELALEEVEKAGEEQAKFENQLKTKVMKLENELEMAQ QSAGGRDTRFLRNEICQLEKQLEQKDRELEDMEKELEKEKKVNEQLALRNEEAENENS KLRRENKRLKKKNEQLCQDIIDYQKQIDSQKETLLSRRGEDSDYRSQLSKKNYELIQY LDEIQTLTEANEKIEVQNQEMRKNLEESVQEMEKMTDEYNRMKAIVHQTDNVIDQLKK ENDHYQLQVQELTDLLKSKNEEDDPIMVAVNAKVEEWKLILSSKDDEIIEYQQMLHNL REKLKNAQLDADKSNVMALQQGIQERDSQIKMLTEQVEQYTKEMEKNTCIIEDLKNEL QRNKGASTLSQQTHMKIQSTLDILKEKTKEAERTAELAEADAREKDKELVEALKRLKD YESGVYGLEDAVVEIKNCKNQIKIRDREIEILTKEINKLELKISDFLDENEALRERVG LEPKTMIDLTEFRNSKHLKQQQYRAENQILLKEIESLEEERLDLKKKIRQMAQERGKR SATSGLTTEDLNLTENISQGDRISERKLDLLSLKNMSEAQSKNEFLSRELIEKERDLE RSRTVIAKFQNKLKELVEENKQLEEGMKEILQAIKEMQKDPDVKGGETSLIIPSLERL VNAIESKNAEGIFDASLHLKAQVDQLTGRNEELRQELRESRKEAINYSQQLAKANLKI DHLEKETSLLRQSEGSNVVFKGIDLPDGIAPSSASIINSQNEYLIHLLQELENKEKKL KNLEDSLEDYNRKFAVIRHQQSLLYKEYLSEKETWKTESKTIKEEKRKLEDQVQQDAI KVKEYNNLLNALQMDSDEMKKILAENSRKITVLQVNEKSLIRQYTTLVELERQLRKEN EKQKNELLSMEAEVCEKIGCLQRFKEMAIFKIAALQKVVDNSVSLSELELANKQYNEL TAKYRDILQKDNMLVQRTSNLEHLECENISLKEQVESINKELEITKEKLHTIEQAWEQ ETKLGNESSMDKAKKSITNSDIVSISKKITMLEMKELNERQRAEHCQKMYEHLRTSLK QMEERNFELETKFAELTKINLDAQKVEQMLRDELADSVSKAVSDADRQRILELEKNEM ELKVEVSKLREISDIARRQVEILNAQQQSRDKEVESLRMQLLDYQAQSDEKSLIAKLH QHNVSLQLSEATALGKLESITSKLQKMEAYNLRLEQKLDEKEQALYYARLEGRNRAKH LRQTIQSLRRQFSGALPLAQQEKFSKTMIQLQNDKLKIMQEMKNSQQEHRNMENKTLE MELKLKGLEELISTLKDTKGAQKVINWHMKIEELRLQELKLNRELVKDKEEIKYLNNI ISEYERTISSLEEEIVQQNKFHEERQMAWDQREVDLERQLDIFDRQQNEILNAAQKFE EATGSIPDPSLPLPNQLEIALRKIKENIRIILETRATCKSLEEKLKEKESALRLAEQN ILSRDKVINELRLRLPATAEREKLIAELGRKEMEPKSHHTLKIAHQTIANMQARLNQK EEVLKKYQRLLEKAREEQREIVKKHEEDLHILHHRLELQADSSLNKFKQTAWDLMKQS PTPVPTNKHFIRLAEMEQTVAEQDDSLSSLLVKLKKVSQDLERQREITELKVKEFENI KLQLQENHEDEVKKVKAEVEDLKYLLDQSQKESQCLKSELQAQKEANSRAPTTTMRNL VERLKSQLALKEKQQKALSRALLELRAEMTAAAEERIISATSQKEAHLNVQQIVDRHT RELKTQVEDLNENLLKLKEALKTSKNRENSLTDNLNDLNNELQKKQKAYNKILREKEE IDQENDELKRQIKRLTSGLQGKPLTDNKQSLIEELQRKVKKLENQLEGKVEEVDLKPM KEKNAKEELIRWEEGKKWQAKIEGIRNKLKEKEGEVFTLTKQLNTLKDLFAKADKEKL TLQRKLKTTGMTVDQVLGIRALESEKELEELKKRNLDLENDILYMRAHQALPRDSVVE DLHLQNRYLQEKLHALEKQFSKDTYSKPSISGIESDDHCQREQELQKENLKLSSENIE LKFQLEQANKDLPRLKNQVRDLKEMCEFLKKEKAEVQRKLGHVRGSGRSGKTIPELEK TIGLMKKVVEKVQRENEQLKKASGILTSEKMANIEQENEKLKAELEKLKAHLGHQLSM HYESKTKGTEKIIAENERLRKELKKETDAAEKLRIAKNNLEILNEKMTVQLEETGKRL QFAESRGPQLEGADSKSWKSIVVTRMYETKLKELETDIAKKNQSITDLKQLVKEATER EQKVNKYNEDLEQQIKILKHVPEGAETEQGLKRELQVLRLANHQLDKEKAELIHQIEA NKDQSGAESTIPDADQLKEKIKDLETQLKMSDLEKQHLKEEIKKLKKELENFDPSFFE EIEDLKYNYKEEVKKNILLEEKVKKLSEQLGVELTSPVAASEEFEDEEESPVNFPIY (SEQ ID NO:8), or a polypeptide sequence which has at least 80%, 85%, 87%, 90%, 92%, 93%, 94%, 95%, 98%, 99% or more amino acid sequence identity thereto. In one embodiment, the gene is ALMS1, and the nucleotide sequence comprises 1 aggcgggcgg cactgcgcct aagctgggcc acaaccgcca gtcagggctc tccccttccc 61 ctccctcccc ccctcctcct cctcctctgc cgcccagagc gagacaccaa catggagccc 121 gaggatctgc catggccggg cgagctggag gaggaggagg aggaggagga ggaggaggag 181 gaggaggaag aggaggaggc tgcagcggcg gcggcggcga acgtggacga cgtagtggtc 241 gtggaggagg tggaggaaga ggcggggcgg gagttggact ccgactctca ctacgggccc 301 cagcatctgg aaagtataga cgacgaggag gacgaggagg ccaaggcctg gctgcaggcg 361 caccccggca ggattttgcc tccgctgtcg cccccgcagc accgctactc ggagggcgag 421 cggacctccc tggagaagat tgttccattg acctgtcatg tatggcaaca gatagtatat 481 caaggcaata gtagaacaca aatttctgat actaatgtgg tctgtttgga aacaacagct 541 cagcggggtt ctggggatga tcagaaaaca gaatcttggc attgtcttcc tcaagaaatg 601 gactcttccc aaaccttgga tacatcccag actaggttta atgtgagaac ggaagatact 661 gaagtgacag acttcccctc tctggaggag ggcatattga cgcaatcaga aaatcaagta 721 aaggaaccca acagagatct cttctgttct ccactgctag tcatacaaga tagctttgct 781 tctcctgatt tgcctttgct gacctgtttg acacaagacc aagaatttgc gcctgattct 841 ttatttcatc aaagtgaact aagttttgca cctctgaggg gaattcctga taagtctgaa 901 gatactgaat ggtcttctcg accatcggaa gttagtgaag ctttattcca ggctactgca 961 gaagtagctt cagacttagc aagcagtcgc tttagtgtat ctcagcaccc gcttataggc 1021 agcacagctg ttgggtctca gtgccctttt ttaccttctg aacaagggaa taatgaagag 1081 actatttcgt ctgttgatga actgaaaatt cccaaagact gtgatcgtta tgatgatctt 1141 tgttcatata tgtcatggaa gacacgaaaa gatacacagt ggcctgaaaa caatttagct 1201 gataaagatc aagtttcagt tgcaacttca tttgacataa ctgatgaaaa catagctact 1261 aaaagaagtg accattttga tgctgctcgt tcatatgggc agtattggac acaggaagat 1321 tcatctaagc aggcagaaac atatttaacc aagggcctgc aggggaaggt tgagtctgac 1381 gtcattactc tggatggcct aaatgaaaat gctgttgtat gcagtgaaag agttgctgaa 1441 ctacaaagaa agccaacaag agagtcggaa tatcactctt cagatctcag aatgttgagg 1501 atgtctcctg acactgtgcc aaaggctcct aaacatttaa aagcaggaga cacttctaaa 1561 ggaggcatag ctaaagttac tcaatccaac ttgaagtcag gcatcactac cactcctgtt 1621 gattcagaca ttggatctca tttatccttg tcccttgagg acctgtctca gttggctgta 1681 agttctcctc tagaaactac tactggtcaa cacactgata ctctcaacca aaagacatta 1741 gcagatactc atctaactga agagactctg aaagtcacag ctattcctga accagctgac 1801 cagaagactg caacaccaac agtactctct agttcccact cacatagggg gaagcccagc 1861 attttctacc agcagggctt gccagacagt catctaactg aagaggcttt gaaagtttca 1921 gctgctcctg gactagctga ccagacaact ggcatgtcaa ctctaacctc tacttcctac 1981 tcacatagag agaagcctgg tactttttac caacaagagt taccagagag taacttaacc 2041 gaagagcctt tggaagtttc agctgctcct ggcccagtgg agcagaagac gggaatacct 2101 acagtatcct ctacatccca ctcacatgga gaggacctcc tctttttcta tcgacagacc 2161 ttgccagatg gtcatctaac tgatcaggct ctgaaagtct cagctgtgtc tggaccagct 2221 gaccagaaga ctgggacagc aacagtactc tctactcccc actcacatag agagaagcct 2281 ggtatttttt accaacaaga gtttgcagac agtcatcaaa ctgaagagac tcttactaaa 2341 gtttcagcca ctcctggacc agctgaccag aagactgaga taccagcagt acagtctagt 2401 tcttactcac aaagagaaaa gcctagtatt ttgtacccac aggacttagc agacagtcat 2461 ctacctgaag agggtctgaa agtttcagct gttgctggac cagctgacca gaagactggc 2521 ctaccaacag taccctctag tgcatactca cacagagaga agctccttgt tttctaccaa 2581 caggccttgc tggacagcca tctacccgaa gaggctctga aagtttcagc tgtttctgga 2641 ccagctgacg gaaagactgg gacaccagct gtaacctcta cttcctctgc gtcctcttca 2701 cttggagaaa agcccagtgc tttctatcag cagaccttac ccaatagtca tctaactgaa 2761 gaggctctga aagtatcaat tgttcctgga ccaggtgatc agaagactgg gataccctca 2821 gcaccatcta gtttctactc acacagagag aagcccatta ttttttccca gcagaccctg 2881 ccagactttc ttttccctga agaagctctg aaggtttcag ctgtttctgt attggctgcc 2941 cagaagactg ggacaccaac agtgtcctct aattctcact cacatagcga gaaatctagt 3001 gttttctacc agcaagagtt gccagacagt gatctaccta gagaatctct gaaaatgtct 3061 gctattcctg gactgactga ccagaagact gtcccaacac caacagtacc ttcaggttcc 3121 ttctcacata gagagaagcc cagtattttc tatcaacagg agtggccaga tagttatgca 3181 actgaaaagg ctctgaaagt ttcaactggc cctggaccag ctgaccagaa gactgagata 3241 ccagcagtac agtctagttc ttacccacag agggagaagc ctagtgtttt gtacccacag 3301 gtgttatcag acagtcatct acctgaagag agtctgaaag tttcagcctt ccctggacca 3361 gctgaccaga tgactgacac accagcagta ccgtctactt tctactcaca aagagagaag 3421 cctggtattt tctaccaaca gaccttgcca gagagtcatc tgcctaaaga ggctctgaaa 3481 atttcagtag ctcctggact agcagaccag aagactggca caccaactgt aacctcaact 3541 tcctactcac aacatagaga aaagcccagc attttccacc agcaggcctt gccaggtact 3601 catatacctg aagaggctca gaaagtttca gctgttactg gaccaggtaa ccagaagact 3661 tggataccaa gagtactttc taccttctac tcacaaagag agaaacctgg tattttctat 3721 caacagacct tgccaggtag tcacatacct gaagaggcac agaaagtttc acctgttctt 3781 ggaccagctg accagaagac tgggacacca actccaacct ctgcttctta ctcacacaca 3841 gagaagcctg gtattttcta ccaacaggtc ttgccagata atcatccaac tgaagaggct 3901 ctgaaaattt cagttgcctc tgaaccagtt gaccagacaa ctggcacacc agctgtaacc 3961 tctacttcct actcacaata tagagagaag cccagcattt tctaccaaca gtcgttgcca 4021 agtagtcatc taactgaaga ggctaagaat gtttcagcgg ttcctggacc agctgaccag 4081 aagactgtga taccaatttt accctctact ttctactcac acacagagaa gcctggtgtt 4141 ttctaccaac aggtcttgcc acatagtcat ccaactgaag aggctctgaa aatttcagtt 4201 gcctctgaac cagttgacca gacaactggc acaccaactg taacctctac ttcttactca 4261 caacatacag agaagccgag tattttctac caacagtcgt tgccaggtag tcatctaact 4321 gaagaggcta agaacgtttc agcggttcct ggaccaggtg accggaagac tgggatacca 4381 actttaccct ctactttcta ctcacacaca gagaagcctg gtagtttcta ccaacaggtc 4441 ttgccacata gtcatctacc tgaagaggct ttggaagttt cagttgctcc tggaccagtt 4501 gaccagacga ttggcacacc aactgtaacc tccccttcca gctcatttgg agagaagccc 4561 attgttatct acaaacaggc ctttccagag ggtcatctac ctgaagagtc tctgaaagtt 4621 tcagttgctc ctggaccagt tggccagaca actggcgcac caactataac ctctccttcc 4681 tactcacaac atagagcaaa gtctggcagt ttctaccaac tggcattgct aggtagtcaa 4741 atacctgaag aggctctcag agtttcttct gctcctggac cagctgacca gacaactggc 4801 ataccaacca taacctctac ttcctactca tttggagaga agccgattgt taactacaaa 4861 caggcctttc cagatggtca tctacctgaa gaggctctga aagtttccat tgtttctgga 4921 cctactgaaa aaaagactga cataccagca ggacctttag gttccagtgc acttggagag 4981 aagcccatta ctttctaccg gcaggctctg ctagacagtc ctctaaataa agaggttgtg 5041 aaagtttcag ctgctcctgg accagctgac cagaagactg agacattacc agtacattct 5101 actagctact caaatagggg gaagcctgtc attttctacc agcagaccct atcagacagt 5161 catttacctg aagaagctct gaaagttcca cctgttcctg gaccagatgc ccagaagact 5221 gagacaccat cagtatcctc tagtttatac tcatatagag agaagcccat tgtcttctac 5281 caacaggccc tgccagacag tgagctaact caagaagctc tgaaagtttc agctgttcct 5341 caaccagctg accagaagac tgggttatct actgtaactt cctctttcta ttcacataca 5401 gagaagccta atatttctta ccagcaagag ttgccagata gtcatctaac tgaagaggct 5461 ctgaaagttt caaatgttcc tggaccagct gaccagaaga ctggggtatc aacagtaacc 5521 tctacttcct actcacacag agagaagccc attgtttcct accagcgaga gttgccgcat 5581 tttactgaag caggtttgaa aattttaaga gttcctggac cagctgacca gaagactgga 5641 ataaacatcc tgccctctaa ttcctaccca cagagagagc actctgtcat ttcttatgag 5701 caggagttgc cagatcttac tgaagtaact ttgaaagcaa taggggttcc tgggcctgct 5761 gaccagaaga ctgggataca aatagcatcc tctagttcct actcaaatag agagaaggcc 5821 agtatttttc atcagcagga gttgccagat gttactgaag aagctttaaa tgtttttgtt 5881 gttcctggac aaggtgaccg gaagactgag ataccaacag tacctttaag ttactactca 5941 cgtagagaga agcccagtgt tatctctcaa caggagttgc cagacagtca tctcacagaa 6001 gaggctctga aagtttcacc tgtttctata ccagcagagc agaagactgg gataccaata 6061 ggactgtcta gttcctactc acattcacat aaagagaaac tcaagatttc aactgtgcat 6121 ataccagatg accagaaaac tgagtttcca gcagctaccc ttagttccta ctcacaaata 6181 gagaagccca agatttcaac tgtgattgga ccaaatgacc agaagactcc atcccagaca 6241 gcttttcata gttcctattc tcaaacagta aagcccaata ttttatttca acagcagttg 6301 ccagatagag atcaaagtaa aggtattcta aagatttcag ctgtccctga actaactgat 6361 gtgaatactg gaaaaccagt atctctctct agttcttatt ttcacagaga gaaatcgaat 6421 attttcagtc cacaggaatt gccaggtaga catgtaactg aagatgtgct gaaggtttca 6481 acaattcctg gaccagctgg ccagaaaaca gtattaccaa cagctcttcc tagttccttt 6541 tcacatcgag agaaaccaga tattttctat caaaaggatt tgccagatag acatctaact 6601 gaagatgctc taaagatctc aagtgctctt gggcaagctg atcaaattac cggattacaa 6661 acagttccct ctggtactta ctcacatggt gagaatcaca agcttgtttc agaacatgtc 6721 caaaggctaa tagataattt gaattcttct gactccagtg ttagctcaaa taatgtgctt 6781 ttaaattctc aggctgatga cagagttgta ataaataaac cagaatctgc aggttttaga 6841 gatgttggct ctgaagaaat ccaggatgca gaaaatagtg ctaaaactct taaggaaatt 6901 cggacacttt tgatggaggc agaaaatatg gcactgaaac gatgcaattt tcctgctccc 6961 cttgcccgtt tcagagatat tagtgatatt tcatttatac aatctaagaa ggtggtttgc 7021 ttcaaagaac cctcttccac gggtgtatct aatggtgatt tgcttcacag acagccattc 7081 acagaggaaa gcccaagcag caggtgcata cagaaggata ttggcacaca gacgaatttg 7141 aaatgccgga gaggcattga aaattgggag tttattagtt caactacagt tagaagtcct 7201 ctacaggaag cagagagcaa agtcagtatg gcattagaag aaactcttag gcaatatcaa 7261 gcagccaaat ctgtaatgag gtctgaacct gaagggtgta gtggaaccat tgggaataaa 7321 attattatcc ctatgatgac tgtcataaaa agtgattcaa gtagtgatgc cagtgatgga 7381 aatggttcct gctcgtggga cagtaattta ccagagtctt tggaatcagt ttctgatgtt 7441 cttctaaact tctttccata tgtttcaccc aagacaagta taacagatag cagggaggaa 7501 gagggtgtgt cagagagtga ggatggtggt ggtagcagtg tagattcact ggctgcacat 7561 gtgaaaaacc ttctgcaatg tgaatcctca ctgaatcatg ctaaagaaat actcagaaat 7621 gcagaggaag aggaaagccg ggtacgagca catgcctgga atatgaagtt caatttagca 7681 catgattgtg gatactccat ttcagaatta aatgaagatg acaggaggaa agtagaagag 7741 atcaaggcag agttatttgg tcatggaaga acaactgact tgtccaaggg tttacagagt 7801 ccacggggaa tgggatgcaa gccagaagct gtatgtagtc acattattat tgagagccat 7861 gaaaagggat gtttccggac tctaacttct gaacatccac aactagatag acacccttgt 7921 gctttcagat ctgctggacc ctcagaaatg accagaggac ggcagaaccc atcatcatgc 7981 agagccaagc atgtcaacct ttctgcatcc ttagaccaga acaactccca tttcaaagtt 8041 tggaattcct tgcagttaaa aagtcattcc ccatttcaga actttatacc tgatgaattc 8101 aaaatcagca aaggtcttcg aatgccattc gatgaaaaga tggacccttg gctgtcagaa 8161 ttagtagaac ctgcttttgt gccacctaaa gaagtggatt ttcattcttc atcacaaatg 8221 ccgtccccag aacccatgaa aaagtttact acctccatca ctttttcatc tcaccgacat 8281 tctaaatgca tttccaattc ctctgttgtt aaggttggtg ttactgaagg tagccagtgt 8341 actggagcat ctgtgggggt atttaattct catttcactg aagaacaaaa tcctcccaga 8401 gatcttaaac agaaaacctc ttccccttca tcatttaaaa tgcatagtaa ttcacaagat 8461 aaagaagtga ctattttagc agaaggtaga aggcaaagcc aaaaattacc tgttgatttt 8521 gagcgttctt ttcaagaaga aaaaccctta gaaagatcag attttacagg cagtcattct 8581 gagcccagta ccagggcaaa ttgtagcaat ttcaaggaaa ttcagatttc tgataaccat 8641 acccttatta gcatgggcag accaagttcc accctaggag taaacagatc gagttccaga 8701 ctaggagtaa aagagaagaa tgtaactata actccagatc ttccttcttg catttttctt 8761 gaacaacgag agctctttga acaaagcaaa gccccacgtg cagatgacca tgtgaggaaa 8821 caccattctc cctctcctca acatcaggat tatgtagctc cagaccttcc ttcttgcatt 8881 tttcttgaac aacgagaact ctttgaacag tgcaaagccc catatgtaga tcatcaaatg 8941 agagaaaacc attctcccct tcctcaaggt caggattcta tagcttcaga ccttccgtct 9001 cccatttctc ttgaacaatg ccaaagcaaa gcgccaggtg tagatgacca aatgaataaa 9061 caccattttc cccttcctca aggtcaggat tgtgtagtgg aaaagaataa tcaacataag 9121 cctaaatcac acatttctaa tataaatgtt gaagccaagt tcaatactgt ggtctcccag 9181 tcagccccaa atcactgtac attagcagca tctgcatcta ctcctccttc aaatagaaaa 9241 gcactttctt gtgttcatat aactctttgt cccaagactt cttccaagtt ggatagtgga 9301 actttagatg aaagattcca ttcattggat gctgcttcta aagcgaggat gaatagtgag 9361 tttaactttg acttacatac tgtatcttcg agatcactgg aaccaacctc caaattattg 9421 accagtaaac ctgtagcaca ggatcaagaa tctttaggtt ttctaggacc taaatcttca 9481 ctggatttcc aagtcgtaca gccttctctt ccagacagta acactattac tcaggacttg 9541 aaaaccatac cttctcagaa tagccagata gtaacctcca ggcaaataca agtgaacatt 9601 tcagatttcg aaggacattc caatccagag gggaccccag tatttgcaga tcgattacca 9661 gagaagatga agaccccact ttctgctttc tctgaaaaat tgtcatctga tgcagtcact 9721 cagataacaa cagaaagtcc agaaaagacc ctattttcat ctgagatttt tattaatgct 9781 gaagatcgtg gacatgaaat tatagagcct ggtaaccaga agctacgcaa agctcctgtc 9841 aagtttgcct catcatcttc agtccaacag gttacttttt ctcgcggcac agatggccag 9901 cctttattat tgccatataa gccttctggt agtaccaaga tgtattatgt tccacaatta 9961 agacaaattc ctccatctcc ggattccaaa tcagatacca ccgttgaaag ctcccattca 10021 ggatccaatg atgccattgc tccagacttc ccagctcagg tgctaggcac aagagatgat 10081 gacctctcag ccactgttaa cattaaacat aaagaaggaa tctacagtaa gagggtagtg 10141 actaaggcat ccttgccagt gggagaaaaa cccttgcaga atgaaaatgc agatgcctca 10201 gttcaagtgc taatcactgg ggatgagaac ctctcagaca aaaaacagca agagattcac 10261 agtacaaggg cagtgactga ggctgcccag gctaaagaaa aagaatcttt gcagaaagat 10321 actgcagatt ccagtgctgc tgctgctgca gagcactcag ctcaagtagg agacccagaa 10381 atgaagaact tgccagacac taaagccatt acacagaaag aggagatcca taggaagaag 10441 acagttcccg aggaagcctg gccaaacaat aaagaatccc tacagatcaa tattgaagag 10501 tccgaatgtc attcagaatt tgaaaatact acccgttctg tcttcaggtc agcaaagttt 10561 tacattcatc atcccgtaca cctaccaagt gatcaagata tttgccatga atctttggga 10621 aagagtgttt tcatgagaca ttcttggaaa gatttctttc agcatcatcc agacaaacat 10681 agagaacaca tgtgtcttcc tcttccttat caaaacatgg acaagactaa gacagattat 10741 accagaataa agagcctcag catcaatgtg aatttgggaa acaaagaagt gatggatact 10801 actaaaagtc aagttagaga ttatccaaaa cataatggac aaattagtga tccacaaagg 10861 gatcagaagg tcaccccaga gcaaacaact cagcacactg tgagtttgaa tgaactgtgg 10921 aacaagtatc gggagcgaca gaggcaacag agacagcctg agttgggtga caggaaagaa 10981 ctgtccttgg tggaccgact tgatcggttg gctaaaattc ttcagaatcc aatcacacat 11041 tctctccagg tctcagaaag tacacatgat gatagcagag gggaacgaag tgtgaaggaa 11101 tggagtggta gacaacagca gagaaataag cttcagaaaa agaagcggtt taaaagccta 11161 gagaaaagcc ataaaaatac aggcgagctt aaaaaaagca aggtgctttc tcatcatcga 11221 gctgggaggt ctaatcaaat taaaattgaa cagattaaat ttgataaata tattctgagt 11281 aaacagccag gttttaatta tataagcaac acttcttcgg attgtcggcc ctcagaggag 11341 agtgagctgc tcacagatac taccaccaac atcctttccg gcaccacttc tactgtcgaa 11401 tcagatatat tgacccaaac agatagagag gtggctctgc acgaaaggag tagctctgtt 11461 tccactattg acactgcccg gctgattcaa gcttttggcc atgaaagagt atgcttgtca 11521 cccagacgaa ttaaattata tagcagcatc accaaccaac agaggagata ccttgagaag 11581 cggagcaaac acagcaagaa agtgctgaat acaggtcatc ccctagtgac ttctgagcac 11641 accagaagga gacacatcca ggtagcaaac catgtgattt cttctgactc tatttcctct 11701 tctgccagta gtttcctgag ctcaaactct actttttgca acaagcagaa tgtacacatg 11761 ttaaacaagg gcatacaagc aggtaacttg gagattgtga acggtgccaa aaaacacact 11821 cgagatgttg ggataacttt cccaactcca agttccagcg aggctaaatt ggaagagaac 11881 agtgatgtga cttcttggtc agaagaaaaa cgtgaagaga aaatgctctt taccggttat 11941 cctgaggaca gaaagttaaa aaagaacaag aagaattccc atgaaggagt ttcctggttt 12001 gttcctgtgg aaaatgtgga gtctagatca aagaaggaaa acgtgcctaa cacttgtggc 12061 cctggcatct cctggtttga accaataacc aagaccagac cctggaggga gccactgcgg 12121 gagcagaact gtcaggggca gcacctggac ggtcggggct acctggcagg cccaggcaga 12181 gaggctggca gagacctact gaagccattt gtgagagcaa cccttcagga atcgcttcag 12241 tttcacagac ctgacttcat ctcccgctct ggggagcgga taaagcgcct gaagttaata 12301 gtccaggaga ggaagctgca gagcatgtta cagaccgagc gggatgcact attcaacatt 12361 gacagggaac ggcagggcca ccagaatcgc atgtgcccgc tgcccaagag agtcttcctg 12421 gctatccaga agaacaagcc tatcagcaag aaggaaatga ttcagaggtc caaacggatt 12481 tatgagcagc ttccagaagt acagaaaaag agagaagaag agaagagaaa atcagaatat 12541 aagtcatacc ggctgcgagc ccagctatat aaaaagagag tgaccaatca acttctgggg 12601 agaaaagttc cctgggactg acacaagttt attttcctca gagccttgga attctatttt 12661 atgaacctag agaagcagaa tccttacttt tgtgagtctg gttgaataaa gcttattctt 12721 tgtccatgtg tattttagaa atagtaactt ctaaagagtc tggaacaaag tggtgattaa 12781 aattcctaat ggtttgggag caatactttc tgcatagtgg ccttgtccaa tggcctgtgt 12841 gttacaatga tatgatcatt tctcaagaat aagtcccttt ttgtatgtgt ttttatactt 12901 ttagaaaata aaaactttag attaactc (SEQ ID NO:9), or a nucleotide sequence which has at least 80%, 85%, 87%, 90%, 92%, 93%, 94%, 95%, 98%, 99% or more nucleic acid sequence identity thereto, or a nucleotide sequence that encodes a polypeptide having MEPEDLPWPGELEEEEEEEEEEEEEEEEEAAAAAAANVDDVVVV EEVEEEAGRELDSDSHYGPQHLESIDDEEDEEAKAWLQAHPGRILPPLSPPQHRYSEG ERTSLEKIVPLTCHVWQQIVYQGNSRTQISDTNVVCLETTAQRGSGDDQKTESWHCLP QEMDSSQTLDTSQTRFNVRTEDTEVTDFPSLEEGILTQSENQVKEPNRDLFCSPLLVI QDSFASPDLPLLTCLTQDQEFAPDSLFHQSELSFAPLRGIPDKSEDTEWSSRPSEVSE ALFQATAEVASDLASSRFSVSQHPLIGSTAVGSQCPFLPSEQGNNEETISSVDELKIP KDCDRYDDLCSYMSWKTRKDTQWPENNLADKDQVSVATSFDITDENIATKRSDHFDAA RSYGQYWTQEDSSKQAETYLTKGLQGKVESDVITLDGLNENAVVCSERVAELQRKPTR ESEYHSSDLRMLRMSPDTVPKAPKHLKAGDTSKGGIAKVTQSNLKSGITTTPVDSDIG SHLSLSLEDLSQLAVSSPLETTTGQHTDTLNQKTLADTHLTEETLKVTAIPEPADQKT ATPTVLSSSHSHRGKPSIFYQQGLPDSHLTEEALKVSAAPGLADQTTGMSTLTSTSYS HREKPGTFYQQELPESNLTEEPLEVSAAPGPVEQKTGIPTVSSTSHSHGEDLLFFYRQ TLPDGHLTDQALKVSAVSGPADQKTGTATVLSTPHSHREKPGIFYQQEFADSHQTEET LTKVSATPGPADQKTEIPAVQSSSYSQREKPSILYPQDLADSHLPEEGLKVSAVAGPA DQKTGLPTVPSSAYSHREKLLVFYQQALLDSHLPEEALKVSAVSGPADGKTGTPAVTS TSSASSSLGEKPSAFYQQTLPNSHLTEEALKVSIVPGPGDQKTGIPSAPSSFYSHREK PIIFSQQTLPDFLFPEEALKVSAVSVLAAQKTGTPTVSSNSHSHSEKSSVFYQQELPD SDLPRESLKMSAIPGLTDQKTVPTPTVPSGSFSHREKPSIFYQQEWPDSYATEKALKV STGPGPADQKTEIPAVQSSSYPQREKPSVLYPQVLSDSHLPEESLKVSAFPGPADQMT DTPAVPSTFYSQREKPGIFYQQTLPESHLPKEALKISVAPGLADQKTGTPTVTSTSYS QHREKPSIFHQQALPGTHIPEEAQKVSAVTGPGNQKTWIPRVLSTFYSQREKPGIFYQ QTLPGSHIPEEAQKVSPVLGPADQKTGTPTPTSASYSHTEKPGIFYQQVLPDNHPTEE ALKISVASEPVDQTTGTPAVTSTSYSQYREKPSIFYQQSLPSSHLTEEAKNVSAVPGP ADQKTVIPILPSTFYSHTEKPGVFYQQVLPHSHPTEEALKISVASEPVDQTTGTPTVT STSYSQHTEKPSIFYQQSLPGSHLTEEAKNVSAVPGPGDRKTGIPTLPSTFYSHTEKP GSFYQQVLPHSHLPEEALEVSVAPGPVDQTIGTPTVTSPSSSFGEKPIVIYKQAFPEG HLPEESLKVSVAPGPVGQTTGAPTITSPSYSQHRAKSGSFYQLALLGSQIPEEALRVS SAPGPADQTTGIPTITSTSYSFGEKPIVNYKQAFPDGHLPEEALKVSIVSGPTEKKTD IPAGPLGSSALGEKPITFYRQALLDSPLNKEVVKVSAAPGPADQKTETLPVHSTSYSN RGKPVIFYQQTLSDSHLPEEALKVPPVPGPDAQKTETPSVSSSLYSYREKPIVFYQQA LPDSELTQEALKVSAVPQPADQKTGLSTVTSSFYSHTEKPNISYQQELPDSHLTEEAL KVSNVPGPADQKTGVSTVTSTSYSHREKPIVSYQRELPHFTEAGLKILRVPGPADQKT GINILPSNSYPQREHSVISYEQELPDLTEVTLKAIGVPGPADQKTGIQIASSSSYSNR EKASIFHQQELPDVTEEALNVFVVPGQGDRKTEIPTVPLSYYSRREKPSVISQQELPD SHLTEEALKVSPVSIPAEQKTGIPIGLSSSYSHSHKEKLKISTVHIPDDQKTEFPAAT LSSYSQIEKPKISTVIGPNDQKTPSQTAFHSSYSQTVKPNILFQQQLPDRDQSKGILK ISAVPELTDVNTGKPVSLSSSYFHREKSNIFSPQELPGRHVTEDVLKVSTIPGPAGQK TVLPTALPSSFSHREKPDIFYQKDLPDRHLTEDALKISSALGQADQITGLQTVPSGTY SHGENHKLVSEHVQRLIDNLNSSDSSVSSNNVLLNSQADDRVVINKPESAGFRDVGSE EIQDAENSAKTLKEIRTLLMEAENMALKRCNFPAPLARFRDISDISFIQSKKVVCFKE PSSTGVSNGDLLHRQPFTEESPSSRCIQKDIGTQTNLKCRRGIENWEFISSTTVRSPL QEAESKVSMALEETLRQYQAAKSVMRSEPEGCSGTIGNKIIIPMMTVIKSDSSSDASD GNGSCSWDSNLPESLESVSDVLLNFFPYVSPKTSITDSREEEGVSESEDGGGSSVDSL AAHVKNLLQCESSLNHAKEILRNAEEEESRVRAHAWNMKFNLAHDCGYSISELNEDDR RKVEEIKAELFGHGRTTDLSKGLQSPRGMGCKPEAVCSHIIIESHEKGCFRTLTSEHP QLDRHPCAFRSAGPSEMTRGRQNPSSCRAKHVNLSASLDQNNSHFKVWNSLQLKSHSP FQNFIPDEFKISKGLRMPFDEKMDPWLSELVEPAFVPPKEVDFHSSSQMPSPEPMKKF TTSITFSSHRHSKCISNSSVVKVGVTEGSQCTGASVGVFNSHFTEEQNPPRDLKQKTS SPSSFKMHSNSQDKEVTILAEGRRQSQKLPVDFERSFQEEKPLERSDFTGSHSEPSTR ANCSNFKEIQISDNHTLISMGRPSSTLGVNRSSSRLGVKEKNVTITPDLPSCIFLEQR ELFEQSKAPRADDHVRKHHSPSPQHQDYVAPDLPSCIFLEQRELFEQCKAPYVDHQMR ENHSPLPQGQDSIASDLPSPISLEQCQSKAPGVDDQMNKHHFPLPQGQDCVVEKNNQH KPKSHISNINVEAKFNTVVSQSAPNHCTLAASASTPPSNRKALSCVHITLCPKTSSKL DSGTLDERFHSLDAASKARMNSEFNFDLHTVSSRSLEPTSKLLTSKPVAQDQESLGFL GPKSSLDFQVVQPSLPDSNTITQDLKTIPSQNSQIVTSRQIQVNISDFEGHSNPEGTP VFADRLPEKMKTPLSAFSEKLSSDAVTQITTESPEKTLFSSEIFINAEDRGHEIIEPG NQKLRKAPVKFASSSSVQQVTFSRGTDGQPLLLPYKPSGSTKMYYVPQLRQIPPSPDS KSDTTVESSHSGSNDAIAPDFPAQVLGTRDDDLSATVNIKHKEGIYSKRVVTKASLPV GEKPLQNENADASVQVLITGDENLSDKKQQEIHSTRAVTEAAQAKEKESLQKDTADSS AAAAAEHSAQVGDPEMKNLPDTKAITQKEEIHRKKTVPEEAWPNNKESLQINIEESEC HSEFENTTRSVFRSAKFYIHHPVHLPSDQDICHESLGKSVFMRHSWKDFFQHHPDKHR EHMCLPLPYQNMDKTKTDYTRIKSLSINVNLGNKEVMDTTKSQVRDYPKHNGQISDPQ RDQKVTPEQTTQHTVSLNELWNKYRERQRQQRQPELGDRKELSLVDRLDRLAKILQNP ITHSLQVSESTHDDSRGERSVKEWSGRQQQRNKLQKKKRFKSLEKSHKNTGELKKSKV LSHHRAGRSNQIKIEQIKFDKYILSKQPGFNYISNTSSDCRPSEESELLTDTTTNILS GTTSTVESDILTQTDREVALHERSSSVSTIDTARLIQAFGHERVCLSPRRIKLYSSIT NQQRRYLEKRSKHSKKVLNTGHPLVTSEHTRRRHIQVANHVISSDSISSSASSFLSSN STFCNKQNVHMLNKGIQAGNLEIVNGAKKHTRDVGITFPTPSSSEAKLEENSDVTSWS EEKREEKMLFTGYPEDRKLKKNKKNSHEGVSWFVPVENVESRSKKENVPNTCGPGISW FEPITKTRPWREPLREQNCQGQHLDGRGYLAGPGREAGRDLLKPFVRATLQESLQFHR PDFISRSGERIKRLKLIVQERKLQSMLQTERDALFNIDRERQGHQNRMCPLPKRVFLA IQKNKPISKKEMIQRSKRIYEQLPEVQKKREEEKRKSEYKSYRLRAQLYKKRVTNQLL GRKVPWD (SEQ ID NO:10), or a polypeptide sequence which has at least 80%, 85%, 87%, 90%, 92%, 93%, 94%, 95%, 98%, 99% or more amino acid sequence identity thereto. Recombinases and Recombination Sites The AAV vectors may include any recombination site which may be employed with the corresponding recombinase, which may be provide in trans, e.g., encoded on one of the AAV vectors or expressed in a host cell. Exemplary recombinases and recombination sited include but are not limited to Cre recombinase and lox sites; FLP recombinase and frt sites; Dre recombinase and rox sites; Nigri recombinase (Vibrio nigirpulchritudo) and noxP sites; Vika recombinase and vox sites; or Panto (Pantoea sp.) recombinase and pox sites. The recombination sites to be employed with viral vector sets include those having mutation(s) in the core sequence, mutations in the left or right flanking sequences (the non-mutated versions are palindromic sequences), or combinations thereof. Core sequence pairs that do not allow strand exchange are “non- compatible”. For example, a lox site has up to about 13, 14 or 15 nucleotides of a left flanking sequence, up to about 8 nucleotides of a core sequence and up to about 13, 14 or 15 nucleotides of a right flanking sequence. Thus, mutations in a reference core sequence include 1, 2, 3, 4, 5, 6, 7, or 8 nucleotide substitutions, wherein the substitutions are not necessarily consecutive. Mutations in a flanking sequence include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 or 13 or more nucleotide substitutions, wherein the substitutions are not necessarily consecutive. In one embodiment, a core sequence has 1, 2, 3, 4, or 5 nucleotide substitutions relative to a reference sequence. In one embodiment, a flanking sequence has 1, 2, 3, 4 or 5 nucleotide substitutions relative to a reference sequence. Exemplary lox sequences include but are not limited to: loxP ATAACTTCGTATA (left) (SEQ ID NO:11) GCATACAT (core) TATACGAAGTTAT (right) (SEQ ID NO:12) loxN ATAACTTCGTATA (left) (SEQ ID NO:13) GTATACCT (core) TATACGAAGTTAT (right) (SEQ ID NO:14) Lox2272 ATAACTTCGTATA (left) (SEQ ID NO:15) GGATACTT (core) TATACGAAGTTAT (right) (SEQ ID NO:16) LoxHT1 ATAACTTCGTATA (left) (SEQ ID NO:17) CTATAGCC (core) TATACGAAGTTAT (right) (SEQ ID NO:18) LoxHT2 ATAACTTCGTATA (left) (SEQ ID NO:19) TACTATAC (core) TATACGAAGTTAT (right) (SEQ ID NO:20) loxJT15 AATTATTCGTATA (left) (SEQ ID NO:21) GCATACAT (core) TATACGAAGTTAT (right) (SEQ ID NO:22) loxJTZ17 ATAACTTCGTATA (left) (SEQ ID NO:23) GCATACAT (core) TATAGCAATTTAT (right) (SEQ ID NO:24) lox1517 AATTATTCGTATA (left) (SEQ ID NO:25) GCATACAT (core) TATAGCAATTTAT (right) (SEQ ID NO:26) loxJT15:N AATTATTCGTATA (left) (SEQ ID NO:27) GTATACCT (core) TATACGAAGTTAT (right) (SEQ ID NO:28) lox1517:N AATTATTCGTATA (left) (SEQ ID NO:29) GTATACCT (core) TATAGCAATTTAT (right) (SEQ ID NO:30) loxJT15:22 AATTATTCGTATA (left) (SEQ ID NO:31) GGATACTT (core) TATACGAAGTTAT (right) (SEQ ID NO:32) loxJTZ17:22 ATAACTTCGTATA (left) (SEQ ID NO:33) GGATACCT (core) TATAGCAATTTAT (right) (SEQ ID NO:34) loxJT15:HT1 AATTATTCGTATA (left) (SEQ ID NO:35) CTATAGCC (core) TATACGAAGTTAT (right) (SEQ ID NO:36) loxJTZ17:HT1 ATAACTTCGTATA (left) (SEQ ID NO:37) CTATAGCC (core) TATAGCAATTTAT (right) (SEQ ID NO:38) loxJT15:HT2 AATTATTCGTATA (left) (SEQ ID NO:39) TACTATAC (core) TATACGAAGTTAT (right) (SEQ ID NO:40) loxJTZ17:HT2 ATAACTTCGTATA (left) (SEQ ID NO:41) TACTATAC (core) TATAGCAATTTAT (right) (SEQ ID NO:42) Lox66 ATAACTTCGTATA (left) (SEQ ID NO:43) GCATACAT (core) TATACGAAcggta (right) (SEQ ID NO:44) Lox71 taccgTTCGTATA (left) (SEQ ID NO:45) GCATACAT (core) TATACGAAGTTAT (right). (SEQ ID NO:46) Exemplary products of recombination include but are not limited to: lox1517 AATTATTCGTATA (left) (SEQ ID NO:47) GCATACAT (core) TATAGCAATTTAT (right) (SEQ ID NO:48) Lox72 taccgTTCGTATA (left) (SEQ ID NO:49) GCATACAT (core) TATACGAAcggta (right) (SEQ ID NO:50) An exemplary core sequence comprises: GX1ATAX2X3T, where X1 is absent or is any one of C, T, A or G; where X2 is absent or is any one of C, T, A or G; or where X3 is absent or is any one of C, T, A or G; or any combination thereof. Another exemplary core sequence comprises: X1X2X3TAX4X5X6, where X1 is absent or is any one of C, T, A or G; where X2 is absent or is any one of C, T, A or G; where X3 is absent or is any one of C, T, A or G; where X4 is absent or is any one of C, T, A or G; where X5 is absent or is any one of C, T, A or G; or where X6 is absent or is any one of C, T, A or G; or any combination thereof. In a specific rAAV pair in a set, the core sequence in at least one lox site (if at least one of the rAAV has two lox sites) binds Cre and is compatible. In a specific rAAV pair in a set the core sequences may be incompatible, e.g., as a result of a mutation such as a nucleotide substitution and /or a deletion(s). In one embodiment, the core sequence is asymmetric. Flanking sequences are not necessarily palindromic as one of the flanking sequences in a specific lox site in a rAAV has one or more nucleotide substitutions and/or a deletion(s). In a specific rAAV pair, one of the lox sites for recombination in one of the rAAVs has a mutation(s) in one of the flanking sequences and one of the lox sites in the other rAAV of a pair for recombination has a mutation(s) in the other flanking sequence. In a specific rAAV pair, one of the lox sites for recombination in one of the rAAVs has a sequence in one of the flanking sequences that differs from the corresponding sequence in the lox site for recombination in the other rAAV. An exemplary left flanking sequence comprises: X1X2X3X4X5TTCGTATA, where X1, X2, X3, X4 or X5, individually, is absent or is any one of C, T, A or G. In one embodiment, X2 and X5 are A. In one embodiment X3 and X4 are T. In one embodiment, a left flanking sequence comprises AATTATTCGTATA (SEQ ID NO:51). In one embodiment, a left flanking sequence comprises ATAACTTCGTATA (SEQ ID NO:52). An exemplary right flanking sequence comprises: TATAX1X2AAX3X4X5X6, where X1, X2, X3, X4, X5 or X6, individually, is absent or is any one of C, T, A or G. In one embodiment X1 and X3 are G. In one embodiment X3 and X4 are T. In one embodiment, a right flanking sequence comprises TATAGCAATTTAT (SEQ ID NO:53). In one embodiment, a right flanking sequence comprises TATACGAAGTTAT (SEQ ID NO:54). The invention will be described by the following non-limiting examples. Example 1 AAV vectors are generated with specific therapeutic genes inserted (e.g., genes encoding ABCA4, USH2A, IFT140, or CEP290) useful for AAV gene therapy to prevent, inhibit or treat, for example, ABCA4-associated retinal degeneration, USH2A-associated Usher syndrome, IFT140-associated retinitis pigmentosa, or CEP290-associated Leber congenital amaurosis. However, any therapeutic gene may be inserted into the described vectors, such as genes encoding MYO7A, PCDH15, CACNA1F, CDH23, or ALMS1, or other large genes that cause or are associated with genetic diseases. In the 2-AAV vector set (Figure 3A), the 5’ vector, which carries the first half of a cargo gene, consists of 2 AAV inverted terminal repeats (ITRs), a promoter, a cloning site to insert the first half of a cargo gene, a splice donor (SD) site (sequence: GTAAGTAACAAGGTTAAAGACAGGTTTAAGGAGACCAATAGAAACT GGGCTTGTCGAGACAGAGAACT TGCGTTTCGAGG) (SEQ ID NO:55), and a loxJT15 (or loxJTZ17) site. The 3’ vector, which carries the second half of the cargo, consists of 2 ITRs, a loxJTZ17 (or loxJT15, if loxJTZ17 is used in the 5’ vector) site, a splice acceptor (SA) site (sequence: GTCTTACTGACATCCACTTTGCCTTTCTCTCCACAG) (SEQ ID NO:56), a cloning site to insert the second half of the cargo, and a transcription termination signal. Instead of the loxJT15 and loxJTZ17 pair, the loxJT15:N + loxJTZ17:N or the loxJT15:22 + loxJTZ17:22, the loxJT15:HT1 + loxJTZ17:HT1, or the loxJT15:HT2 + loxJTZ17:HT2 pair may be used. A CMV promoter is included in the 5’ vector for ubiquitous transgene expression, but other promoters (e.g., EF1α, CAG, CBh, etc.) may be used depending on target cells, where the cargo gene is expressed, and desired expression levels. We synthesized minimal SD and SA sites to maximize the space available for cargo genes. For transcriptional termination and mRNA poly-adenylation, a BGH polyA signal was added to the 3’ vector, but it may be replaced with other polyA signals (e.g., SV40 polyA) as needed. The human ABCA4 gene, the coding sequence of which is ~6.8 kb, was split into two fragments and inserted into the 5’ and the 3’ AAV vectors. To test whether the use of the reaction equilibrium-modifying lox sites increases the production of full-length proteins as intended, a 3’ vector was generated with a canonical loxP site and the production of full-length ABCA4 was compared between loxJTZ17- and loxP-containing 3’ vectors. Due to the size restriction, the CRE expression cassette was provided in a separate vector. As shown in Figure 3B, full-length ABCA4 was produced only when both ABCA4_N and ABCA4_C vectors were transduced with the CRE vector (lanes 4 and 5), and if any of the three was omitted, no full-length ABCA4 was produced. In addition, the 3’ vector with loxJTZ17 yielded 5-10 times more ABCA4 than the one with loxP. A plasmid DNA encoding full-length ABCA4 was transfected and used as a positive control (lane 8). These results demonstrate that all components of our vector set work as intended. For genes larger than 8 kb (up to 12 kb), a vector set is provided composed of three AAV vectors (Fig. 4). The same 5’ vector used in the two-AAV set is used. The 3’ vector is also very similar to the one included in the two-AAV set, but loxJTZ17:22 is used instead of loxJTZ17. The middle vector consists of 2 ITRs, a loxJTZ17 site, a SA site, a cloning site to insert a part of the cargo gene, a SD site, and a loxJT15:22 site. The use of non-compatible pairs prevents nonproductive recombinations (e.g., recombination between the 5’ and the 3’ vectors and the deletion of the middle vector after full assembly). For the 3-AAV set, the coding sequences of Green Fluorescent Protein (GFP; ~0.7 kb), human Bardet-Biedl Syndrome 1 (BBS1; ~1.8 kb; with an HA- tag), and human Leucine Zipper Transcription Factor-Like 1 (LZTFL1; ~1.0 kb; with a FLAG-tag) was inserted into the 5’, middle, and 3’ vectors, respectively. The AAV vectors were delivered to HEK293T cells together with a CRE vector, and the expression of GFP-BBS1-LZTFL1 fusion protein was probed by western blotting. As shown in Figure 4B, GFP-BBS1-LZTFL1 fusion proteins, which were recognized by all 3 antibodies (i.e., anti-GFP, anti-HA, and anti-LZTFL1), were produced only when the 3 AAV vectors and the CRE vector were co- transduced (lane 7). The migration rate of the detected protein is in good agreement with the predicted molecular mass of the full-length fusion protein (~130 kDa). Furthermore, the production of GFP-BBS1-LZTFL1 fusion proteins was CRE-dependent, as they were not produced when the CRE vector was omitted (lane 8). These results demonstrate the functionality of the 3-AAV vector set. For genes larger than 12 kb (up to 16 kb), a vector set composed of four AAV vectors (Figure 5) was prepared. The 5’ and the 3’ vectors are the same as the ones used in the 3-AAV vector set. Two middle vectors are introduced in this set. The first middle vector, which carries CDS2, consists of 2 ITRs, a loxJTZ17 site, a SA site, a cloning site to insert a part of the cargo gene, a SD site, and a loxJT15:N site. The second middle vector, which carries CDS3, consists of 2 ITRs, a loxJTZ17:N site, a SA site, a cloning site to insert a part of the cargo gene, a SD site, and a loxJT15:22 site. For the 4-AAV set, the coding sequences of the N-terminal half of IFT140 (~2.0 kb; with a HA tag), IFT57 (~1.3 kb; with a MYC tag), BBS5 (1.0 kb; with a HA tag), and LZTFL1 (with a FLAG tag) were inserted into the 5’, 1st middle, 2nd middle, and 3’ vectors, respectively. The AAV vectors were delivered to HEK293T cells together with a CRE vector, and the expression of IFT140-IFT57- BBS5-LZTFL1 fusion protein was probed by western blotting. As shown in Figure 5B, IFT140-IFT57-BBS5-LZTFL1 fusion proteins, which were recognized by all 3 antibodies (i.e., anti-HA, anti-MYC, and anti-LZTFL1), were produced only when the four AAV vectors and the CRE expression vector were co- transduced (lane 9). The migration rate of the detected protein was very close to the predicted molecular mass of the full-length fusion protein (~200 kDa). These data demonstrate that the four AAV vectors assemble as intended and validate the functionality of the 4-AAV vector set. Example 2 Adeno-associated virus (AAV) is a proven safe gene delivery vehicle for retinal gene therapy, however, its main drawback is the limited packaging capacity. The study provides an example of a generic and effective gene therapy strategy for large therapeutic genes, e.g., for retinal gene therapy. These strategies are used to develop gene therapy vectors for ABCA4- associated retinal dystrophy. ABCA4 is a member of the A subfamily of ATP- binding cassette transporters and is expressed in both rod and cone photoreceptors with weaker expression in RPE cells. ABCA4 localizes to the rim of the photoreceptor outer segment disc membranes and transports all-trans-retinal (covalently bound to phospholipid) from the luminal leaflet to the cytoplasmic leaflet of these membranes. Importantly, mutations in ABCA4 are the most common cause of Mendelian retinal diseases. In a study of 1000 consecutive families seen by a single clinician, 173 of them (17.3%) were found to have disease-causing genotypes in ABCA4. More than 30,000 people in the U.S. are currently affected with ABCA4-associated retinal diseases. Their specific clinical findings range from an extremely aggressive cone-rod dystrophy that begins in the first decade of life and can result in complete blindness by age 40, to a later onset condition limited to the macula. Regardless of their age of onset, most patients with ABCA4-associated disease lose their high acuity central vision, which is essential for detailed tasks such as reading, driving, and recognizing faces. With no established cure for this disease, there is an urgent need to develop one. Gene therapy is a promising treatment option for inherited retinal degenerative disease such as those resulting from mutations in ABCA4. The use of the vectors described herein allows for highly efficient, AAV-based large gene delivery systems. In one exmplae, the CRE-lox site-specific DNA recombination system as well as mutant derivatives of the loxP site facilitate the reconstitution of therapeutic gene cassettes at the DNA level. Because the approaches described herein take advantage of the efficient gene delivery and the safety of the AAV vector, while overcoming its limitation on the packaging capacity, they deliver full-length therapeutic genes/proteins, and so are useful for patients with loss of function mutations. Other hereditary visual impairment-causing genes that are larger than that limit of AAV include but are not limited to ABCA4, USH2A, CEP290, MYO7A, and PCDH15. Reconstitution of the ABCA4 therapeutic gene cassette at the DNA level utilizing the CRE-lox recombination system Inefficient delivery of AAV vectors (i.e., scarce co-transduction) was not the main factor that limited efficient reconstitution of dual AAV vectors. Instead, inefficient recombination of the vectors in the right configuration (scarce recombination of the 5’ and 3’ vectors in the tail-to-head orientation) was. The CRE-lox site-specific DNA recombination system was used to enhance the recombination efficiency of dual AAV vectors (Figure 7A). The 5’ vector is composed of a CMV promoter, 5’ half of the ABCA4 coding sequence, a splice donor (SD) site, and a lox71 site. The 3’ vector is composed of a lox66 site, a splice acceptor (SA) site, 3’ half of the ABCA4 coding sequence, and a polyA transcription termination signal. The use of lox71 and lox66 sites results in the forward reaction (e.g., generation of the reconstituted ABCA4 expression cassette) favored. CRE recombinase is delivered via a separate AAV vector. ABCA45’ and 3’ plasmids are transfected together with a CRE expression vector into HEK293T cells and the production of full-length ABCA4 proteins confirmed by immunoblotting (Figure 7B). Evaluate the safety and efficacy of the new gene therapy strategies using Abca4- null mice in vivo To demonstrate that the developed AAV5-ABCA4 gene therapy vectors are able to produce full-length ABCA4 proteins in vivo, Abca4-/- mice (strain name: Abca4tm1Ght/J; The Jackson lab #023725) at four weeks of age are injected with 1x109 viral particles via a single subretinal injection. To control for potential viral toxicity, the contralateral eyes of some animals are injected with an equal amount of control AAV without a transgene. Animals are sacrificed at 2-3 weeks post-injection, and ABCA4 protein expression and localization are examined by immunoblotting and immunohistochemistry using antibodies against ABCA4. To demonstrate transgene functionality, Abca4-/- mice at two different ages (4 and 12 weeks of age) receive 1x109 viral particles of the AAV5-ABCA4 vectors via subretinal injection. As above, contralateral eyes are used as a control. Each animal is analyzed via fluorescent ophthalmoscopy, optical coherence tomography (OCT), and electroretinography (ERG) at 4-, 10-, and 24-weeks following injection. In mice, deletion of Abca4 results in the accumulation of autofluorescent lipofuscin-like materials in the RPE, which is detectable between 16 and 40 weeks of age. The level of autofluorescent lipofuscin accumulation in treated vs. contralateral control eyes is directly compared in each animal. Specifically, it is determined if treatment with the AAV5-ABCA4 gene augmentation strategy is capable of slowing or preventing lipofuscin accumulation. Following the final examination, animals are sacrificed, and their eyes are used for biochemical and histological studies. Long-term expression of ABCA4 is validated by immunoblotting. In addition, retinal histology is examined for the presence of any abnormalities and rescue effects. Markers of apoptosis (cleaved caspase 3, 9, and PARP) are examined to evaluate overexpression toxicity in vivo. In summary, the CRE-lox site-specific recombination system and mutant variants of the loxP site facilitate the reconstitution of therapeutic gene cassettes at the DNA level. Although positive outcomes have been reported, the efficiency of the hybrid dual AAV approach needs to be improved. For instance, although GFP expression was detected from hybrid dual AAV vectors, an order of magnitude higher multiplicity of infection (MOI) was needed to achieve a similar level of expression, compared to single AAV-based gene delivery. The limiting factor was not the scarce co-infection of two vectors in individual cells but the scarcity of productive recombination. To improve the recombination efficiency, a new strategy was developed that utilizes the CRE-lox system as well as two mutant derivatives of the canonical loxP site. The lox71 and lox66 sites have mutations in one of the two 13-bp inverted repeats. These sites are normally recognized by CRE recombinase and undergo recombination. After recombination, however, they are converted to loxP and lox72 sites, the latter of which has mutations in both inverted repeats and displays a very low affinity for CRE recombinase. Consequently, the reverse reaction is very slow, and the forward reaction is favored, resulting in the enrichment of the reconstituted ABCA4 cassette. Example 3 Described herein is a novel strategy to deliver large genes using AAVs. Cargo genes are split in 2-4 AAV vectors and reconstituted by using the CRE-lox DNA recombination system. The use of novel lox sites, which were generated by combining non-compatible and reaction equilibrium-modifying lox site variants, enables efficient reconstitution of a therapeutic cassette in a pre-determined configuration. This approach enables the development of AAV-based, generic gene replacement therapy vectors by delivering full-length coding sequences of large disease-causing genes. Development of novel lox site variants for sequence-specific, unidirectional recombination The canonical loxP site consists of two 13-bp inverted repeats (left and right elements; LE and RE, respectively) separated by an asymmetric 8-bp spacer/core sequence (Fig.7A). While the left and right elements are the binding sites of the CRE recombinase, the spacer participates in the strand exchange reaction and dictates the compatibility between lox sites (i.e., whether two lox sites can recombine or not). The asymmetry of the spacer also provides the loxP site with directionality. There are two classes of lox site variants. One is non- compatible mutant variants, which include loxm7, loxN, and lox2272 (Lee & Saito, 1998; Livet et al, 2007; Siegel et al., 2001) (Fig.7A). These variants have mutations within the spacer sequence, and these mutations prevent strand exchange (and consequently recombination) between non-compatible lox sites while allowing recombination between homologous (or compatible) sites. A high- throughput screen identified fully non-compatible and promiscuous lox sites (Missirlis et al., 2006). The second group is reaction equilibrium-modifying variants (Figure 1B). These variants have mutations in either LE or RE but not in both (e.g., loxJT15, loxJTZ17, lox71, and lox66) (Albert et al, 1995; Thomson et al., 2003). The single-element mutations do not affect the binding of CRE to the lox site, and recombination between these mutant lox sites occurs as efficiently as between canonical loxP sites. However, the recombination between LE and RE single mutants produces an LE/RE double mutant and a canonical loxP site. The presence of mutations in both LE and RE significantly reduces the affinity of the LE/RE double mutant to CRE, making the double mutant a poor substrate of CRE. While the recombination between canonical loxP sites is fully reversible as the initial substrates and the products have the same lox sites, the reaction equilibrium is drastically shifted toward the forward direction when LE and RE single mutants are used as substrates because the reverse reaction is much slower than the forward reaction. This causes the CRE-mediated recombination nearly unidirectional when the reaction equilibrium-modifying lox sites are used. Although the CRE-lox system is highly efficient, canonical loxP sites (or any combinations of compatible lox sites) cannot be used to assemble more than two DNA fragments (Fig. 8). This is because when there are two or more compatible lox sites in a single DNA fragment, the intervening “floxed” sequence will be rapidly excised. The reverse reaction (i.e., insertion) is much slower than the forward reaction. Furthermore, if all DNA fragments have compatible lox sites, recombination reactions can occur in any combination. Therefore, the order of DNA fragments in end products cannot be specified and a significant proportion of recombination products will be unintended, non-functional products. Lastly, since the CRE-lox recombination is fully reversible, the reconstituted DNA constantly goes through the assembly-disassembly cycle, limiting the yield of the reconstituted DNAs. In principle, the yields of reconstituted products are 50%, 25%, and 12.5% when 2, 3, and 4 fragments are used as substrates, respectively, even when the excision and the order of DNA fragment problems are disregarded. To overcome the aforementioned problems and enable the reconstitution of large genes using multiple AAV vectors and the CRE-lox DNA recombination system, we devised novel lox sites by combining the non-compatible and the reaction equilibrium-modifying lox site variants (Fig.7C). We chose the loxJT15- loxJTZ17 pair for the reaction equilibrium-modifying mutants because this pair was the most effective in inhibiting the reverse-direction recombination (Thomson et al., 2003). For the non-compatible lox sites, we selected loxN, lox2272, loxm7, and two additional lox sites identified by a high-throughput screen (spacer sequences: CTATAGCC (named loxHT1 herein) and TACTATAC (loxHT2) (Missirlis et al., 2006). The loxN-based pair, for example, was generated by replacing the spacer sequence of loxJT15 and loxJTZ17 (GCATACAT) with that of loxN (GTATACCT). These hybrid lox sites should be non-compatible with one another, preventing the excision of intervening sequences and unintended recombinations (Fig. 8D and 8E). At the same time, they should significantly increase the yield of reconstituted genes by inhibiting reverse reactions, particularly when 3 or more AAV vectors are used (Fig.8F). We first tested whether the hybrid lox sites that we developed were fully non-compatible with one another in mammalian cells. To this end, we designed GFP expression cassettes capable of tracking recombination events between different lox sites (Fig.9 and Fig.10). The first reporter construct, referred to as loxP-2272, is composed of a CMV promoter, a GFP coding sequence, and a loxJT15 (15:P) site followed by an in-frame 156-bp segment from the human CEP290 C-terminus (C290C; amino acids 2428-2479) and a stop codon. The coding sequence of the GFP+C290C fusion protein is followed by a loxJTZ17:m7 hybrid (hereafter denoted as 17:m7 for brevity), a FLAG tag, a 17:HT1 hybrid, an HA tag, a 17:HT2 hybrid, a MYC tag, a 17:2272 hybrid, and a V5 tag. Stop codons were added after each of the FLAG, HA, MYC, and V5 tags. In the absence of recombination, this reporter generates 35-kDa GFP+C290C fusion proteins, which can be detected by our CEP290 antibody (Fig.9B and Fig.10). However, when recombination takes place, the C290C fragment is excised and one of the four tags is spliced to GFP in-frame, depending on which lox site recombines with the loxJT15 (15:P) site. For instance, recombination between the 15:P and the 17:HT1 sites results in the production of GFP+HA fusion proteins (~30 kDa). Of note, recombination events not involving the 15:P site, such as between 17:m7 and 17:2272, do not lead to the fusion of associated tags with GFP and therefore go unreported. We created four additional reporter constructs (loxP-N, lox2272-N, loxP- HT2, and lox2272-HT2; Fig. 9A) and examined the compatibility between the hybrid lox sites by co-transfecting these reporters with a CRE expression vector into HEK293T cells. As shown in Fig.9B, reporters containing lox17:N (loxP-N and lox2272-N) expressed GFP+V5 fusion proteins when CRE was present. In contrast, no new GFP fusion proteins were detected in cells transfected with loxP- 2272, loxP-HT2, and lox2272-HT2. These results suggest that the spacer of loxN is partially compatible with those of loxP and lox2272, while loxP and lox2272 are fully incompatible with each other and with loxm7, loxHT1, and loxHT2. As these reporters do not provide information about recombination events that do not involve the first lox site, this experiment does not assess the compatibility among loxm7, loxHT1, and loxHT2. As a positive control for Western blotting (lane 12), we included lysates from cells transfected with FLAG-LZTFL1, HA-LZTFL1, and MYC-BBS1 to rule out the possibility of Western blotting failure, with β-actin serving as a loading control. Based on these data, we selected the spacer sequences of loxP, lox2272, and loxHT1 for the assembly of up to four AAV vectors. The spacers of loxm7 and loxHT2 may be used instead of loxHT1. CRE-lox mediated reconstitution of large genes: three-AAV vector set To evaluate the feasibility of our approach in reconstituting large genes delivered via three separate AAV vectors, we designed a set of three AAV vectors containing the coding sequences of three human genes: the initial 1,923 bp of IFT140, BBS1, and LZTFL1 (Fig. 11A). The first vector comprises a CMV promoter, the first 1,923 bp of the IFT140 coding sequence, a splice donor (SD) site, and a loxJT15 site. An HA tag was added to the N-terminus of IFT140 for the detection of expressed proteins. The second vector contains a loxJTZ17 site, a splice acceptor (SA) site, the coding sequence of BBS1 (1,775 bp; including linker sequences), a SD site, and a lox15:2272 site. The third vector is composed of a lox17:2272 site, a SA site, the LZTFL1 coding sequence (988 bp; including a linker sequence), and a bovine growth hormone (BGH) transcription termination signal. When these three AAV vectors undergo recombination in the correct arrangement, they will lead to the reconstitution of an expression cassette encoding IFT140+BBS1+LZTFL1 fusion proteins. These AAV vectors, all utilizing serotype 2, were transduced individually or in various combinations to HEK293T cells. Two different doses were used: a “low” dose, where 293T cells were transduced at a multiplicity of infection (MOI) of 1.5x104 for each vector, and a “high” dose, with cells being transduced at an MOI of 6.0x104 for each vector. CRE recombinase was delivered via a separate AAV vector (AAV-EF1α-CRE) with an MOI of 0.3x104 for the low dose and 1.2x104 for the high dose. As shown in Figure 4B, we observed robust expression of the IFT140+BBS1+LZTFL1 fusion protein (red arrowheads) using both HA and LZTFL1 antibodies for detection at both low and high doses (upper and lower panels, respectively). The migration rate of the protein was consistent with the predicted molecular weight of the full-length fusion protein, approximately 172 kDa. Endogenous LZTFL1 (marked by blue arrowheads) served as a loading control. Although expression of the IFT140+BBS1+LZTFL1 fusion protein was not detected in the absence of CRE (lane 8) at the low dose, a small amount was detectable at the high dose. These proteins are presumably attributed to the spontaneous, random recombination of AAV genomes occurring after internalization. Our data indicate that the CRE- and hybrid lox site-mediated reconstitution is significantly more efficient than the trans-splicing approach for reconstituting large genes. CRE-lox mediated reconstitution of large genes: four-AAV vector set We next tested the reconstitution of large genes using four AAV vectors. To this end, we prepared AAV vectors containing the coding sequences of the initial 1,923 bp of IFT140, IFT57, BBS5, and LZTFL1 (Fig.12A). The first and last AAV vectors that contained the IFT140 and LZTFL1 coding sequences were the same ones used in the 3-AAV set above. The second vector was constructed with a loxJTZ17 site, a SA site, the IFT57 coding sequence (1,330 bp; including linker sequences), a SD site, and a lox15:HT1 site. The third vector was composed of a lox17:HT1 site, a SA site, the BBS5 coding sequence (1,090 bp; including linker sequences), a SD site, and a lox15:2272 site. These AAV vectors were delivered to 293T cells at an MOI of 2.5x104 per vector. The AAV-EF1α-CRE vector was transduced at an MOI of 0.5x104. If recombination of these AAV vectors occurs in the correct configuration, it will result in the reconstitution of an expression cassette encoding IFT140+IFT57+BBS5+LZTFL1 fusion proteins with a predicted molecular weight of ~200 kDa. As shown in Fig. 12B, the production of the IFT140+IFT57+BBS5+LZTFL1 fusion protein was confirmed by immunoblotting using HA and LZTFL1 antibodies (lane 5). The fusion protein appeared to be unstable and some of them were truncated near the C-terminus, exhibiting doublets. When any of the four AAV vectors was omitted, the full- length fusion protein was not produced (lanes 1-4). Furthermore, in the absence of CRE, the fusion protein was not produced (lane 6). These data validate the successful assembly of the four AAV vectors as intended and underscore the efficacy of our CRE-lox-mediated recombination approach. Reconstitution of ABCA4 by CRE-lox mediated recombination We split the human ABCA4 gene, the coding sequence of which is 6,819 bp, into two segments (3,405 bp and 3,414 bp) and inserted them into the 5’ and the 3’ vectors of the CRE/lox set, respectively (Fig.13A). To test whether the use of the reaction equilibrium-modifying lox sites (i.e., loxJT15 and loxJTZ17) increases the production of full-length proteins as intended, we generated two variations of 3’ vectors, one with a canonical loxP site and the other with a loxJTZ17 site. The 5’ vector contained a CMV promoter and a loxJT15 site, which undergoes recombination with both loxP and loxJTZ17 sites. Due to the size restriction, the CRE expression cassette was delivered via a separate AAV vector. Dual AAV- ABCA4 vectors were delivered to 293T cells at an MOI of 3x104 (per vector) and AAV-EF1α-CRE was transduced at an MOI of 1x104. As shown in Fig. 13B, full-length ABCA4 proteins (~260 kDa) were produced only when both ABCA4_N and ABCA4_C vectors were transduced with the CRE vector (lanes 4 and 5), and if any of the three vectors were omitted, no full-length ABCA4 was produced. In addition, the 3’ vector with loxJTZ17 yielded 5-10 times more ABCA4 than the one with loxP. A plasmid DNA encoding full-length ABCA4 was transfected and used as a positive control (lane 8). These results demonstrate that the use of loxJT15 and loxJTZ17 pair enhances the yield of reconstituted expression cassettes. Reconstitution of IFT140 by CRE-lox mediated recombination We applied the CRE-lox-mediated DNA recombination approach to IFT140, a gene associated with retinitis pigmentosa (RP) and short-rib thoracic dysplasia (OMIM; PMID 26216056, 2696873522503633, 23418020). Although the full- length IFT140 coding sequence (4,389 bp) is small enough to be accommodated within a single AAV vector, additional regulatory sequences such as a promoter, a transcription termination signal, and two inverted terminal repeats (ITRs) must be included in the gene therapy vector, and the addition of such sequences makes the IFT140 expression cassette to exceed the AAV’s packaging capacity. Therefore, at least two AAV vectors are required to deliver the IFT140 gene. Among various dual AAV approaches developed to date, the split-intein-mediated protein trans-splicing method has demonstrated notable effectiveness (Li et al, 2008; Tornabene et al, 2019; Villiger et al, 2018). Among split inteins, gp41 split inteins are one of the most efficient in facilitating protein trans-splicing (our unpublished data). We compared the efficacy of the CRE-lox-mediated DNA recombination approach with that of the gp41 split-intein-mediated protein trans- splicing. We constructed two sets of dual AAV vectors for the delivery of the IFT140 gene. The first set, designed for the CRE-lox approach (Fig. 14A), consists of the 5’ vector that contains a CMV promoter, the first 1,923 bp of the IFT140 coding sequence, an SD site, and a lox15:2272 site and the 3’ vector that contains a lox17:2272 site, an SA site, the rest of the IFT140 coding sequence (2,466 bp), and a BGH transcription termination signal. Since IFT140 is relatively small for dual AAV vectors, there is space to include the CRE gene within the IFT140 vectors. In this regard, we incorporated the CRE coding sequence, along with an N-terminal T2A “self-cleaving” peptide, into the 5’ vector. A BGH polyA signal was also added following the CRE gene. For the protein trans-splicing approach, we chose to split the IFT140 protein at amino acids D767/C768 (Fig. 15). This splitting position was determined based on the IFT140 domain structure and the amino acid residues known to support protein splicing (Shah et al, 2013). The 5’ vector of the second set (Fig.14B) consists of a CMV (or CBh) promoter, the initial 2,301 bp of the IFT140 coding sequence, the N-terminal gp41 split intein (IntN), and a BGH transcription termination signal. The 3’ vector within this set contains the same CMV promoter, the C-terminal gp41 split intein (IntC), the rest of the IFT140 coding sequence (2,088 bp), and a BGH transcription termination signal. To facilitate protein detection, an HA tag was introduced at the N-terminus of IFT140 in both sets. Additionally, we used an IFT140 antibody (140-C Ab), which was raised against human IFT140 aa1114-1462, to detect the C-terminal portion of the protein. Upon transduction into 293T cells (with an MOI of 3x104 for each vector; serotype 2), both sets of IFT140 dual AAV vectors demonstrated efficient production of full-length IFT140 proteins (lanes 2 and 5 in Figure 7C; black arrowheads). However, cells transduced with the protein trans-splicing set exhibited significant levels of unconjugated “half” proteins (lane 5; asterisks). These data indicate that, when an equal number of AAV vectors are transduced, the CRE-lox-mediated recombination approach is at least as effective as the protein trans-splicing approach in producing full-length proteins. Furthermore, the CRE-lox method holds an additional advantage of generating little to no truncated protein products. As a positive control, a plasmid DNA encoding full-length IFT140 with an N-terminal HA tag was transfected and included (lane 6). We further investigated whether the CRE/lox-based dual AAV-IFT140 vectors can produce full-length IFT140 proteins in mouse retinas. To this end, wild-type mouse eyes were subretinally administered with two CRE/lox sets of dual AAV-IFT140 vectors: one with a CMV promoter and the other with a CBh promoter. Both sets of AAV vectors were prepared with the AAV5 serotype and injected at the dose of 5x109 vg per vector. Treated and some of the contralateral control eyes were collected two weeks post-injection and the production of full- length IFT140 proteins was examined by immunoblotting. As shown in Fig.14D, robust expression of full-length IFT140 was detected in all animals injected. These data demonstrate that the CRE/lox-mediated DNA reconstitution approach is a highly reliable method to deliver large genes using AAV. Reconstitution of PCDH15 by CRE-lox mediated recombination Mutations in PCDH15 cause Usher syndrome type 1F (USH1F), which is characterized by profound congenital hearing impairment and progressive vision loss (Ahmed et al, 2001; Alagramam et al, 2001a; Alagramam et al, 2001b). The full-length human PCDH15 CDS spans 5,865 bp, necessitating two AAV vectors for delivery. We applied the split-intein and CRE/lox approaches to PCDH15 and created dual AAV vectors (Figs.16A-16B). As the combined payload capacity of two AAV vectors is ~9 kb, we included the CRE gene (~1.65 kb; with an internal ribosome entry site (IRES) for translation) within the 5’ vector for the CRE/lox set. Notably, the CRE gene becomes “self-inactivated” as recombination progresses and becomes separated from its promoter. For the split-intein set, we designed two variations, where the split occurs at F926/S927 and F1035/T1036. PCDH15 is a single-pass transmembrane protein, with its N-terminal two-thirds situated on the extracellular side of the plasma membrane and the remainder on the cytoplasmic side. While a signal peptide is present at the N-terminus of PCDH15 (and PCDH15_N) for extracellular translocation, it is absent in the C- terminal half. To facilitate the extracellular translocation of IntC (and ensure the presence of IntN and IntC in the same cellular compartments), we introduced the signal peptide of PCDH15 (N-terminal 26 residues) to IntC (Fig.16B). When transduced to 293T cells, the CRE/lox-based dual AAV-PCDH15 vectors robustly produced full-length PCDH15 (Fig. 16C, lane 9). In contrast, although the split-intein-based AAV-PCDH15 vectors efficiently produced the expected individual truncated proteins (lanes 1, 2, 4, and 5), the reconstituted full- length proteins were barely detectable or undetectable (lanes 3 and 6). These data indicate that the CRE/lox method is a more suitable approach for PCDH15. We then applied the CRE-lox-mediated DNA recombination approach to CDH23 gene therapy vectors. Inactivating mutations of CDH23 cause Usher syndrome type 1D (USH1D), which is characterized by profound congenital hearing impairment and progressive vision loss (Bolz et al, 2001; Di Palma et al, 2001). The full-length human CDH23 CDS is 10,065 bp long, requiring three AAV vectors. As the total payload capacity of 3 AAV vectors is ~14 kb (excluding ITRs), we split the CDH23 CDS into 3 pieces (2,176 bp, 4,077 bp, and 3,812 bp) and included the CRE gene (with a T2A peptide) in the 5’ vector (Figure 9A). The loxJT15 and loxJTZ17 pair was used to join the 5’ and the middle vectors and the lox15:2272 and lox17:2272 pair was used for the middle and the 3’ vectors. Since CDH23 is a type-I single transmembrane protein with an N-terminal signal peptide, an HA tag was inserted after the signal peptide for protein detection. A CBh promoter and a BGH polyA signal were used as a promoter and a transcription termination signal, respectively. When transduced to 293T cells at an MOI of 3x104 (per vector), full- length CDH23 proteins were readily detected by immunoblotting (Figure 9B; red arrowhead). A plasmid containing a full-length CDH23 expression cassette was used as a positive control (lane 5), and β-actin was used as a loading control. In addition, we delivered these vectors to wild-type mouse eyes by subretinal injections (serotype: AAV5, dose: 3x109 vg per vector), and expression of full- length CDH23 proteins was detected in all eyes injected with the triple AAV vector sets (Fig.17C, lanes 4-7). Discussion Reconstitution of therapeutic genes via the CRE-lox-mediated DNA recombination has several advantages compared to other approaches that have been described thus far. First, compared to natural recombination-dependent approaches such as trans-splicing, overlapping, and hybrid dual or triple AAV approaches ((Carvalho et al., 2017; Dyka et al., 2014; Dyka et al., 2019; Ghosh et al., 2008)), the CRE-lox-mediated recombination significantly improves the recombination efficiency and the yield of correctly reconstituted genes. This is especially true when triple or quadruple AAV vectors are used. The use of non- compatible, hybrid lox sites prevents the excision of floxed sequences, ensures recombination in a pre-determined configuration, and inhibits the disassembly of reconstituted genes (Figs.8D-8F). The improved efficiency and yield reduce the number of AAV particles needed to transduce target cells, and the use of fewer AAV vectors reduces the potential risks of viral vector-derived toxicity and inflammation. Second, the CRE-lox-mediated DNA recombination approach provides more flexibility regarding splitting positions compared to the protein trans- splicing approach. The efficiency of protein trans-splicing is influenced by the amino acid residues adjacent to split inteins (Chong et al, 1998; Iwai et al., 2006; Shah et al., 2013). The first residue within the C-extein is particularly important, and Cys, Ser, and Thr residues are strongly preferred. This constraint greatly limits the number of possible locations where a protein may be split. Moreover, protein truncations can affect a protein’s structure, stability, and localization, and these factors also influence the overall efficiency and yield of the protein reconstitution. If the target gene encodes a transmembrane or secreted protein, the topology and secretion of each protein fragment should be considered when determining splitting positions. Finding splitting positions for protein trans-splicing ideally requires identifying sites where neither the process of trans-splicing is inhibited, nor the folding and stability of each protein fragment is affected by truncation, while the size of each fragment should be small enough to fit into single AAV vectors. Additionally, it is desirable that the truncated proteins localize to the same compartment or close locations to increase the likelihood of engagement. Identifying optimal splitting positions is challenging and usually involves comparing multiple candidate sites empirically. And the complexity increases if the target gene requires 3 or 4 AAV vectors. In contrast, when using the CRE-lox approach, protein structure, stability, localization, and topology are not factors to consider since the reconstitution happens at the DNA level. Cargo capacity expansion can be achieved by merely adding additional sets of non-compatible lox sites to AAV vectors. Another significant advantage of the CRE-lox approach over protein trans- splicing is the lack or minimal production of truncated proteins. Protein trans- splicing requires the production of “half” proteins before reconstitution, which can have dominant negative or harmful effects if continuously expressed. In contrast, truncated protein production is either absent or low when the CRE-lox strategy is used because the AAV vectors lack a polyA signal, which stabilizes mRNA, or a promoter. Although ITRs have some intrinsic promoter activities, they are very weak in most cells. When the CRE gene is included in the 5’ vector, a truncated protein and CRE are initially produced. However, the vector is converted to a full- length therapeutic cassette and the production of truncated proteins and CRE diminishes as recombination progresses. The lack or minimal production of truncated proteins may be crucial for certain genes if such protein products are toxic to cells, and the “self-inactivation” feature of the CRE-containing 5’ vector provides an additional layer of safety to the CRE-lox approach. Lastly, although the CRE-lox approach requires the delivery of CRE in addition to therapeutic genes, the practical payload capacity of AAV vectors with the CRE-lox approach is either comparable with or larger than that of the split intein-based approach. The protein trans-splicing approach requires each AAV vector to have its own promoter and transcription termination signal to produce therapeutic gene products and split inteins. The repeated inclusion of transcriptional regulatory elements erodes the AAV vector’s combined payload capacity. In contrast, the CRE-lox approach only requires one promoter and one transcriptional termination signal for the entire therapeutic gene, which becomes more beneficial as more AAV vectors are needed. One notable concern of the CRE-lox approach is the prolonged expression of CRE in transduced cells. Prolonged expression of CRE could lead to unintended recombination events in the human genome, potentially resulting in unwanted mutations or genomic instability. Moreover, prolonged CRE expression could also lead to immune responses, which may limit the effectiveness of AAV gene therapies. This could potentially result in the destruction of cells expressing the AAV vectors or a reduction in the efficacy of the AAV gene therapy over time. In this regard, the inclusion of CRE in 5’ vectors and being “self-inactivated” by recombination significantly reduces this risk. Alternatively, an inducible promoter or destabilization domain-fused CRE recombinase may be used. In addition, although numerous transgenic rodent lines expressing CRE have been produced thus far and some phenotypes have been reported (Schmidt et al, 2000), constitutive expression of CRE doesn’t appear to cause serious health concerns in rodents. Like other medical treatments, it is important to consider the potential risks and benefits of CRE-lox-dependent AAV gene therapies. In summary, the CRE-lox approach offers a simple, versatile, and efficient platform for producing AAV gene therapy vectors capable of delivering large genes. As this approach delivers full-length genes, the gene therapy vectors developed using this approach have the potential to be generally applicable to all patients with loss-of-function mutations. The following statements are intended to describe and summarize various embodiments of the invention according to the foregoing description in the specification. Statements 1. A set of AAV vectors comprising: a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; and a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence. 2. A set of AAV vectors comprising: a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third lox site comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; and a third AAV vector having a genome comprising an ITR linked to a fourth lox site comprising a fourth left flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence or the fourth core sequence, wherein the third core sequence and the fourth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence. 3. A set of AAV vectors comprising: a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third lox site comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; a third AAV vector having a genome comprising an ITR linked to a fourth lox site comprising a fourthleft flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a splice donor site linked to a fifth lox site comprising a fifth left flanking sequence linked to a fifth core sequence linked to a fifth right flanking sequence linked to an ITR a fourth AAV vector having a genome comprising an ITR linked to a sixth lox site comprising a sixth left flanking sequence linked to a sixth core sequence linked to a sixth right flanking sequence linked to a splice acceptor linked to a fourth portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence, the fourth core sequence, the fifth core sequence and the sixth core sequence, wherein the third core sequence and the fourth core sequence are compatible, but are not compatible with the fifth core sequence and the sixth core sequence, wherein the fifth core sequence and the sixth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence, and wherein the fifth left flanking sequence and the sixth right flanking sequence have one or more mutations relative to the fifth left flanking sequence and the sixth right flanking sequence or the fifth right flanking sequence and the sixth left flanking sequence have one or more mutations relative to the sixth right flanking sequence and the fifth left flanking sequence. 4. The set of statements 1, 2 or 3 further comprising a vector encoding Cre. 5. The set of statements 1, 2 or 3 wherein one of the vectors encodes Cre. 6. The set of statements 1, 2 or 3 wherein the gene encodes ABCA4, USH2A, IFT140, CEP290, MYO7A, PCDH15, CACNA1F, CDH23, OTOF, DYSF, DMD, CFTR, RP1, EYS, TSC2, NF1, ATM, LAMA2, SPG11, SPG15, SACS, or ALMS1, or a variant thereof. 7. The set of any one of statements 1 to 6 wherein each vector in the set is the same serotype. 8. The set of any one of statements 1 to 7 wherein each ITR in the set is from the same serotype. 9. The set of any one of statements 1 to 8 which is in a composition. 10. A host cell infected with a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR and a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence. 11. A host cell infected with a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third lox site comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; and a third AAV vector having a genome comprising an ITR linked to a fourth lox site comprising a fourth left flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence or the fourth core sequence, wherein the third core sequence and the fourth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence. 12. A host cell infected with a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third lox site comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; a third AAV vector having a genome comprising an ITR linked to a fourth lox site comprising a fourthleft flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a splice donor site linked to a fifth lox site comprising a fifth left flanking sequence linked to a fifth core sequence linked to a fifth right flanking sequence linked to an ITR; a fourth AAV vector having a genome comprising an ITR linked to a sixth lox site comprising a sixth left flanking sequence linked to a sixth core sequence linked to a sixth right flanking sequence linked to a splice acceptor linked to a fourth portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence, the fourth core sequence, the fifth core sequence and the sixth core sequence, wherein the third core sequence and the fourth core sequence are compatible, but are not compatible with the fifth core sequence and the sixth core sequence, wherein the fifth core sequence and the sixth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence, and wherein the fifth left flanking sequence and the sixth right flanking sequence have one or more mutations relative to the fifth left flanking sequence and the sixth right flanking sequence or the fifth right flanking sequence and the sixth left flanking sequence have one or more mutations relative to the sixth right flanking sequence and the fifth left flanking sequence. 13. The host cell of statements 10, 11 or 12 which expresses Cre. 14. The host cell of statements 10, 11, 12 or 13 which is infected with a virus that encodes Cre. 15. The host cell of any one of statements 10 to 14 wherein the host cell is infected with a composition comprising all of the vectors. 16. The host cell of any one of statements 10 to 15 which is a mammalian host cell. 17. A method to express a gene in a mammalian cell, comprising infecting the cell with a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; and a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence; or a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third lox site comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; and a third AAV vector having a genome comprising an ITR linked to a fourth lox site comprising a fourth left flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence or the fourth core sequence, wherein the third core sequence and the fourth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence; or a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third lox site comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; a third AAV vector having a genome comprising an ITR linked to a fourth lox site comprising a fourthleft flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a splice donor site linked to a fifth lox site comprising a fifth left flanking sequence linked to a fifth core sequence linked to a fifth right flanking sequence linked to an ITR; a fourth AAV vector having a genome comprising an ITR linked to a sixth lox site comprising a sixth left flanking sequence linked to a sixth core sequence linked to a sixth right flanking sequence linked to a splice acceptor linked to a fourth portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence, the fourth core sequence, the fifth core sequence and the sixth core sequence, wherein the third core sequence and the fourth core sequence are compatible, but are not compatible with the fifth core sequence and the sixth core sequence, wherein the fifth core sequence and the sixth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence, and wherein the fifth left flanking sequence and the sixth right flanking sequence have one or more mutations relative to the fifth left flanking sequence and the sixth right flanking sequence or the fifth right flanking sequence and the sixth left flanking sequence have one or more mutations relative to the sixth right flanking sequence and the fifth left flanking sequence. 18. A method to express a gene in a mammal, comprising administering to the mammal an effective amount of a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR and a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence; or a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third lox site comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; and a third AAV vector having a genome comprising an ITR linked to a fourth lox site comprising a fourth left flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence or the fourth core sequence, wherein the third core sequence and the fourth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence, or a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third lox site comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; a third AAV vector having a genome comprising an ITR linked to a fourth lox site comprising a fourthleft flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a splice donor site linked to a fifth lox site comprising a fifth left flanking sequence linked to a fifth core sequence linked to a fifth right flanking sequence linked to an ITR a fourth AAV vector having a genome comprising an ITR linked to a sixth lox site comprising a sixth left flanking sequence linked to a sixth core sequence linked to a sixth right flanking sequence linked to a splice acceptor linked to a fourth portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence, the fourth core sequence, the fifth core sequence and the sixth core sequence, wherein the third core sequence and the fourth core sequence are compatible, but are not compatible with the fifth core sequence and the sixth core sequence, wherein the fifth core sequence and the sixth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence, and wherein the fifth left flanking sequence and the sixth right flanking sequence have one or more mutations relative to the fifth left flanking sequence and the sixth right flanking sequence or the fifth right flanking sequence and the sixth left flanking sequence have one or more mutations relative to the sixth right flanking sequence and the fifth left flanking sequence. 19. The method of statement 18 wherein the mammal is a human. 20. The method of statements 18 or 19 wherein the vectors are systemically administered. 21. The method of statements 18 or 19 wherein the vectors are locally administered. 22. The method of any one of statements 18 to 21 wherein the vectors are injected. 23. The method of any one of statements 18 to 22 wherein the gene is a therapeutic gene. 24. The method of any one of statements 18 to 22 wherein the gene is a prophylactic gene. 25. The method of any one of statements 18 to 23 wherein the mammal has ABCA4-associated retinal degeneration, USH2A-associated Usher syndrome, IFT140-associated retinitis pigmentosa, or CEP290-associated Leber congenital amaurosis. 26. The method of any one of statements 18 to 25 wherein the amount administered prevents, inhibits or treats one or more symptoms of a disease. 27. The method of any one of statements 18 to 26 wherein a composition comprises the vectors that are administered. 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While in the foregoing specification, this technology has been described with many details that have been set forth for purposes of illustration and it will be apparent to those skilled in the art that the technology is susceptible to additional embodiments and that certain of the details herein may be varied considerably without departing from the basic principles of the technology. The specific methods, devices and compositions described herein examples and not intended as limitations on the scope of the invention. Other objects, aspects, and embodiments will occur to those skilled in the art upon consideration of this specification and are encompassed within the spirit of the invention as defined by the scope of the claims. It will be readily apparent to one skilled in the art that varying substitutions and modifications can be made to the technology disclosed herein without departing from the scope and spirit of the technology. The technology illustratively described herein suitably can be practiced in the absence of any element or elements, or limitation or limitations, which is not specifically disclosed herein as essential. The methods and processes illustratively described herein suitably can be practiced in differing orders of steps, and the methods and processes are not necessarily restricted to the orders of steps indicated herein or in the claims. Under no circumstances can the patent be interpreted to be limited to the specific examples or embodiments or methods specifically disclosed herein. Under no circumstances can the patent be interpreted to be limited by any statement made by any Examiner or any other official or employee of the Patent and Trademark Office unless such statement is specifically and without qualification or reservation expressly adopted in a responsive writing by Applicants. The terms and expressions that have been employed are used as terms of description and not of limitation, and there is no intent in the use of such terms and expressions to exclude any equivalent of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the technology as claimed. Thus, it will be understood that although the present technology has been specifically disclosed and optional features, modification and variation of the concepts herein disclosed can be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this technology as defined by the appended claims and statements of the invention. The technology has been described broadly and generically herein. Each of the narrower species and subgeneric groupings falling within the generic disclosure also form part of the technology. This includes the generic description of the technology with a proviso or negative limitation removing any subject matter from the genus, regardless of whether or not the excised material is specifically recited herein. In addition, where features or aspects of the technology are described in terms of Markush groups, those skilled in the art will recognize that the technology is also thereby described in terms of any individual member or subgroup of members of the Markush group.

Claims

WHAT IS CLAIMED IS: 1. A set of AAV vectors comprising: a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; and a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence.
2. A set of AAV vectors comprising: a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third lox site comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; and a third AAV vector having a genome comprising an ITR linked to a fourth lox site comprising a fourth left flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence or the fourth core sequence, wherein the third core sequence and the fourth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence.
3. A set of AAV vectors comprising: a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third lox site comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; a third AAV vector having a genome comprising an ITR linked to a fourth lox site comprising a fourthleft flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a splice donor site linked to a fifth lox site comprising a fifth left flanking sequence linked to a fifth core sequence linked to a fifth right flanking sequence linked to an ITR a fourth AAV vector having a genome comprising an ITR linked to a sixth lox site comprising a sixth left flanking sequence linked to a sixth core sequence linked to a sixth right flanking sequence linked to a splice acceptor linked to a fourth portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence, the fourth core sequence, the fifth core sequence and the sixth core sequence, wherein the third core sequence and the fourth core sequence are compatible, but are not compatible with the fifth core sequence and the sixth core sequence, wherein the fifth core sequence and the sixth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence, and wherein the fifth left flanking sequence and the sixth right flanking sequence have one or more mutations relative to the fifth left flanking sequence and the sixth right flanking sequence or the fifth right flanking sequence and the sixth left flanking sequence have one or more mutations relative to the sixth right flanking sequence and the fifth left flanking sequence.
4. The set of claim 1, 2 or 3 further comprising a vector encoding Cre.
5. The set of claim 1, 2 or 3 wherein one of the vectors encodes Cre.
6. The set of claim 1, 2 or 3 wherein the gene encodes ABCA4, USH2A, IFT140, CEP290, MYO7A, PCDH15, CACNA1F, CDH23, OTOF, DYSF, DMD, CFTR, RP1, EYS, TSC2, NF1, ATM, LAMA2, SPG11, SPG15, SACS, or ALMS1, or a variant thereof.
7. The set of any one of claims 1 to 6 wherein each vector in the set is the same serotype.
8. The set of any one of claims 1 to 7 wherein each ITR in the set is from the same serotype.
9. The set of any one of claim 1 to 8 which is in a composition.
10. A host cell infected with a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR and a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence.
11. A host cell infected with a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third lox site comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; and a third AAV vector having a genome comprising an ITR linked to a fourth lox site comprising a fourth left flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence or the fourth core sequence, wherein the third core sequence and the fourth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence.
12. A host cell infected with a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third lox site comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; a third AAV vector having a genome comprising an ITR linked to a fourth lox site comprising a fourthleft flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a splice donor site linked to a fifth lox site comprising a fifth left flanking sequence linked to a fifth core sequence linked to a fifth right flanking sequence linked to an ITR; a fourth AAV vector having a genome comprising an ITR linked to a sixth lox site comprising a sixth left flanking sequence linked to a sixth core sequence linked to a sixth right flanking sequence linked to a splice acceptor linked to a fourth portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence, the fourth core sequence, the fifth core sequence and the sixth core sequence, wherein the third core sequence and the fourth core sequence are compatible, but are not compatible with the fifth core sequence and the sixth core sequence, wherein the fifth core sequence and the sixth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence, and wherein the fifth left flanking sequence and the sixth right flanking sequence have one or more mutations relative to the fifth left flanking sequence and the sixth right flanking sequence or the fifth right flanking sequence and the sixth left flanking sequence have one or more mutations relative to the sixth right flanking sequence and the fifth left flanking sequence.
13. The host cell of claim 10, 11 or 12 which expresses Cre.
14. The host cell of claim 10, 11, 12 or 13 which is infected with a virus that encodes Cre.
15. The host cell of any one of claims 10 to 14 wherein the host cell is infected with a composition comprising all of the vectors.
16. The host cell of any one of claims 10 to 15 which is a mammalian host cell.
17. A method to express a gene in a mammalian cell, comprising infecting the cell with a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; and a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence; or a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third lox site comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; and a third AAV vector having a genome comprising an ITR linked to a fourth lox site comprising a fourth left flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence or the fourth core sequence, wherein the third core sequence and the fourth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence; or a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third lox site comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; a third AAV vector having a genome comprising an ITR linked to a fourth lox site comprising a fourthleft flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a splice donor site linked to a fifth lox site comprising a fifth left flanking sequence linked to a fifth core sequence linked to a fifth right flanking sequence linked to an ITR; a fourth AAV vector having a genome comprising an ITR linked to a sixth lox site comprising a sixth left flanking sequence linked to a sixth core sequence linked to a sixth right flanking sequence linked to a splice acceptor linked to a fourth portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence, the fourth core sequence, the fifth core sequence and the sixth core sequence, wherein the third core sequence and the fourth core sequence are compatible, but are not compatible with the fifth core sequence and the sixth core sequence, wherein the fifth core sequence and the sixth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence, and wherein the fifth left flanking sequence and the sixth right flanking sequence have one or more mutations relative to the fifth left flanking sequence and the sixth right flanking sequence or the fifth right flanking sequence and the sixth left flanking sequence have one or more mutations relative to the sixth right flanking sequence and the fifth left flanking sequence.
18. A method to express a gene in a mammal, comprising administering to the mammal an effective amount of a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR and a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence; or a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third lox site comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; and a third AAV vector having a genome comprising an ITR linked to a fourth lox site comprising a fourth left flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence or the fourth core sequence, wherein the third core sequence and the fourth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence, or a first AAV vector having a genome comprising an ITR linked to a first portion of an open reading frame for a gene of interest linked to a splice donor site linked to a first lox site comprising a first left flanking sequence linked to a first core sequence linked to a first right flanking sequence linked to an ITR; a second AAV vector having a genome comprising an ITR linked to a second lox site comprising a second left flanking sequence linked to a second core sequence linked to a second right flanking sequence linked to a splice acceptor linked to a second portion of an open reading frame for the gene of interest linked to a splice donor site linked to a third lox site comprising a third left flanking sequence linked to a third core sequence linked to a third right flanking sequence linked to an ITR; a third AAV vector having a genome comprising an ITR linked to a fourth lox site comprising a fourthleft flanking sequence linked to a fourth core sequence linked to a fourth right flanking sequence linked to a splice acceptor linked to a third portion of an open reading frame for the gene of interest linked to a splice donor site linked to a fifth lox site comprising a fifth left flanking sequence linked to a fifth core sequence linked to a fifth right flanking sequence linked to an ITR a fourth AAV vector having a genome comprising an ITR linked to a sixth lox site comprising a sixth left flanking sequence linked to a sixth core sequence linked to a sixth right flanking sequence linked to a splice acceptor linked to a fourth portion of an open reading frame for the gene of interest linked to a transcription termination signal linked to an ITR, wherein the first core sequence and the second core sequence are compatible but are not compatible with the third core sequence, the fourth core sequence, the fifth core sequence and the sixth core sequence, wherein the third core sequence and the fourth core sequence are compatible, but are not compatible with the fifth core sequence and the sixth core sequence, wherein the fifth core sequence and the sixth core sequence are compatible, wherein the first left flanking sequence and the second right flanking sequence have one or more mutations relative to the second left flanking sequence and the first right flanking sequence or the first right flanking sequence and the second left flanking sequence have one or more mutations relative to the second right flanking sequence and the first left flanking sequence, wherein the third left flanking sequence and the fourth right flanking sequence have one or more mutations relative to the fourth left flanking sequence and the third right flanking sequence or the third right flanking sequence and the fourth left flanking sequence have one or more mutations relative to the fourth right flanking sequence and the third left flanking sequence, and wherein the fifth left flanking sequence and the sixth right flanking sequence have one or more mutations relative to the fifth left flanking sequence and the sixth right flanking sequence or the fifth right flanking sequence and the sixth left flanking sequence have one or more mutations relative to the sixth right flanking sequence and the fifth left flanking sequence.
19. The method of claim 18 wherein the mammal is a human.
20. The method of claims 18 or 19 wherein the vectors are systemically administered.
21. The method of claims 18 or 19 wherein the vectors are locally administered.
22. The method of any one of claims 18 to 21 wherein the vectors are injected.
23. The method of any one of claims 18 to 22 wherein the gene is a therapeutic gene.
24. The method of any one of claims 18 to 22 wherein the gene is a prophylactic gene.
25. The method of any one of claims 18 to 23 wherein the mammal has ABCA4-associated retinal degeneration, USH2A-associated Usher syndrome, IFT140-associated retinitis pigmentosa, or CEP290-associated Leber congenital amaurosis.
26. The method of any one of claims 18 to 25 wherein the amount administered prevents, inhibits or treats one or more symptoms of a disease.
27. The method of any one of claims 18 to 26 wherein a composition comprises the vectors that are administered.
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