AU2015204349B2 - Use of interfering RNA in the production of transgenic animals - Google Patents

Abstract

The invention provides cells and animals, as well as methods of producing cells and animals, that express at least one interfering RNA molecule to regulate the expression of a specific gene or family of genes. The invention further provides novel iRNA molecules, as well 5 as DNA templates for producing iRNA molecules.

Description

USE OF INTERFERING RNA IN THE PRODUCTION OF TRANSGENIC ANIMALS

This patent application claims priority to U.S.S.N. 60/523,938, filed November 21, 2003, the contents of which are herein incorporated by reference.

This application is a divisional application of Australian patent application no. 2012205138, which is a divisional of Australian patent application no. 2004316293, the entire disclosures of which are incorporated herein by reference.

FIELD OF THE INVENTION

The invention provides cells and animals, as well as methods of producing cells and animals, that express at least one interfering RNA molecule to regulate the expression of a specific gene or family of genes. The invention further provides novel iRNA molecules, as well as DNA templates for producing iRNA molecules.

BACKGROUND OF THE INVENTION

Reference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the art.

To exploit the potential of transgenic cells and animals in both research and therapeutic use, practical techniques must exist to control the expression of exogenous and endogenous gene transcription, and that can be adapted to produce animals in which either endogenous or exogenous gene function is heritably eliminated. Current techniques are limited in their ability to meet these requirements.

Targeted disruption of gene function is presently accomplished via techniques including microinjection or transfection of exogenous inhibitory nucleic acids, mutagenesis, and homologous recombination. Traditionally, a selected gene has been disrupted in cells by recombination with a targeting vector or by random disruption with an integration vector. Cells in which the genes of interest are disrupted can be confirmed using, for example, a selection marker inserted into the genome, or by functionally testing for the gene of interest. Once the disruption has been confirmed in the cell, a heterozygous animal can be produced by cloning via somatic cell nuclear transfer or production of offspring from embryonic stem cells. The heterozygous animal can then sometimes be bred to produce homozygous animals in which the desired gene disruption is present in each allele so that the full gene complement is rendered non-functional. The heterozygous animal can also be subject to further genetic targeting or mutagenesis. (Shastry et al. Mol. Cellul Biochem. 136:171-182 (1994) and Galli-Taliadoros et al. (1995) J. Immunol. Meth 181:1-15 (1995)).

Although potentially valuable, traditional techniques require time consuming and laborious production and screening programs, and demonstrate a very low success rate: Furthermore, the commonly used techniques axe limited to organisms which are known to be receptive to genetic manipulation (where, for example, selectable marker genes, the ability to control genetic segregation, or sexual reproduction have been proven). Because of their low success rate, these techniques are also limited to plications in which a large number of cells or organisms can be sacrificed to isolate the desired phenotype, hi addition, the known techniques axe not readily applied to tiie modulation of exogenous genes, such as those introduced to a cell by viral infection, or to genes with redundant functions which do not lead to different assessable phenotypes. Similarly, because the gene disruption must be maintained in a homozygous state to obtain the desired phenotype, this technique cannot be widely adopted due to the required inbreeding. Any application that benefits from genetic diversity is not amenable to current methodologies.

An alternative technology for disrupting the expression of a gene has recently emerged. RNA interference (iRNA) was originally described in the model organism. C. degaus (Fire et al. Nature 391:806-311 (1998); U.S. Patent No. 6,506,559 to Fire et al). Genetic and biochemical data, primarily arising from studies in low®: eukaryotes, indicate possible mechanisms for RNA interference. Small, noncoding RNA molecules mediate a posttranscriptional gene-silencing mechanism that regulates the expression of developmental genes by inhibiting the translation of target mRNAs. This mechanism is common to plants, fungi, and animals, and the generation of these microRNAs (miRNAs, also known as small inhibitory RNAs or siRNAs) involves a series of sequential steps, where primary RNA transcripts (pri-miRNAs) are cleaved in the nucleus to smaller pre-miRNAs. RNase El, such as Drosha, is a nuclease that executes the initiation step of nriRNA processing in the nucleus (Lee et al (25 September 2003) Nature 425,415-419). Drosha cleaves prkniKNA to release pre-miRNA These are transported to the cytosol where Dicer, a member of the RNAse EC nuclease family, further processes them to yield mature miRNAs from the pre-miRNAs. MiRNAs associate with multicomponent ribonucleoprotein complexes, or RISCs, which effect the silencing of the target mJRNA molecules (Holding, C. “Modeling miRNA > mechanisms”, The Scientist, September 25, 2003). RISC binds to only one strand of the double stcandedmiRNA molecule. The other strand is degraded by the cell.

In plants, insects, and nematodes, RNA interference is the only practical method of generating targeted knockout (K.O) genotypes. However, until recently, RNA interference technology did not appear to be applicable to mammalian systems. In mammals, dsRNA activates dsKNA-activated protean kinase (PER), resulting in an apoptotic cascade and cell death (Dear et al (1597) Proc Natl Acad Sci USA Apr 1:94(7):3279-83.). Thus, ENA interference appeared to tie limited to genetic modulation of lower eukaryotes. However, Elbashir and colleagues in 2001 discovered that PKR activation requires dsRNA longer than about 30 base pairs. Therefore, short ENA sequences can be introduced into a mammalian cell without initiating an apoptotic cascade. Based on data developed in C. degans, siENA sequences of 21-23 base pahs were known to be effective in limiting gene expression. Therefore, by providing these sequences in isolation, it became possible to target reduced gene expression while circumventing the cell's natural defense mechanism (Elbashir et al., (2001) Nature 411:494-498). Within 3 months of the Elbashir ei al. publication, a range of siENA molecules, all less than 30 base pairs long, bad been demonstrated to effectively reduce gene expression in mammalian cells (Caplen et al. (2001) Proc Natl Acad Sci 98(17): 9742-9747). These double stranded siENA molecules contained a sense strand and an antisense strand. Subsequent to these discoveries, several groups have identified some additional strategies to stabilize double stranded interfering ENA molecules, as well as create different types of iRNA molecules, to introduce them into cells. U.S. Patent No. 6,506,559 to Fire et al claims methods to inhibit expression of a target gene in a cell in vitro by introduction of a ENA into the cell in an amount sufficient to inhibit expression of a target gene, wherein the ENA is a double-stranded molecule with a first strand consisting essentially of a ribonucleotide sequence which corresponds to a nucleotide sequence of the target gene and a second strand consisting essentially of a ribonucleotide sequence which is complementary to the nucleotide sequence of the target gene, wherein the first and the second ribonucleotide strands are separate complementary strands that hybridize to each other to form said double-stranded molecule, and the double-stranded molecule inhibits expression of the target gene. PCT Publication No. WO 03/012052 by Caplen et al. discloses small synthetic double stranded ENA molecules, fifteen to forty nucleotides in length, with a 3’ or 5’ overhang of about 0-5 nucleotides on each strand, wherein the sequence of the double stranded RNA is substantially identical to a portion of mKNA or transcript of the target gene. This publication also discloses arrays of siENA that can be used to test the effects of gene ‘silencing’ on cell function. U.S. Publication No. 2003/0166282 by Brown et al. discloses high potency siENA molecules. This publication describes methods of synthesis, such as enzymatic, of siENA molecules, as well as the use of modified nucleotide analogs in the siENA molecule.

The delivery of small, double stranded RNA molecules into cells is not amenable to in vivo use, in part due to inefficiency and uncertainty of the delivery of die molecules and also because ft results in only transient expression, of the iRNA. The next advance in iRNA technology was the production of iRNA molecules inside die cell from DNA templates to obtain stable expression of die iRNA molecule in a cell. U.S. Patent No. 6,573,099 and PCT Publication No. WO 99749029 by Benitec Australia Ltd. claim isolated genetic constructs which are capable of delaying, repressing or otherwise reducing the expression of a target gene in an animal cell which is transfected with the genetic construct, wherein the genetic construct contains at least two copies of a structural gene sequence. The structural gene sequence is described as a nucleotide sequence which, is substantially identical to at least a region of the target gene, and wherein at least two copies of the structural gene sequence are placed operably under the control of a single promoter sequence such that at least one copy of die structural gene sequence is placed operably in the sense orientation under the control of the promoter sequence.

In 2002, Brummelkamp et al. (Science (2002) 296:550-553) reported a stable vector system for expressing siRNA in mammalian cells. The vector contained an RNA polymerase HI HI promoter, followed "by a siRNA sequence and a poly-T tail (pSUPER). The siRNA contained a sense strand, a loop sequence of rive, seven or nine nucleotides and an antisense sequence. Also in 2002, Brummerlkamp et al (Cancer Cell (published online August 22, 2002) reported die use of a retroviral to express siRNA (pRETRO-SUPER). PCT Publication WO 03/006477 by the University of Massachusetts discloses RNA hairpins structures that provide increased stability to the dsKNA The hairpins, made of a stem complementary to a target and a second stem complementary to it and a loop portion connecting the two, are putatively cleaved inside the cell to provide a duplexed eoKNA Such dsKNA molecules are substrates for the Dicer enzyme, as described above. The publication also discloses expression constructs containing DNA encoding such siRNA molecules under the control of exogenous promoters, such as Pol H or PolHI. U.S. Publication No. 2003/0108923 by Tuschl et al describes isolated RNA from about 21 to about 23 nucleotides in length that mediates RNA interference of an mRNA to which it corresponds, as well as isolated DNA encoding the same. PCT Publication No. WO 03/023015 by the California Institute of Technology discloses a method of expressing an siRNA in a cell using a retroviral vector system. Further, this publication indicates that siRNA expression may be useful for the treatment or prevention of infection by inhibiting aspects of the life cycle of a pathogen through interference with a target nucleic acid in a viral genome or a host cell gene that is necessary for viral replication. This publication is drawn specifically to the treatment of human viral infections. The constructs disclosed include at least one RNA Pol ΓΠ promoter, a RNA sense region, a RNA antisense region and a loop region separating the sense and antisense regions in different orientations. U.S. Patent Application No. 2003/0148519 by Engelke, et al. describes hairpin. RNA structures for expression in a cell. This application describes expression cassettes for expressing siRNA and RNA hairpins in a cells, driven off of exogenous promoter elements, such as the U6 RNA polymerase promoter. PCT Publication No. WO 03/056012 by Cancer Research Technology, Ltd. describes a system for stable expression of siRNA in a celL The system comprises a RNA polymerase HI (Pol ID) promoter, a region encoding a siRNA, and a transcriptional termination element comprising five consecutive thymine residues. Ibis publication discloses that multiple siRNA sequences may be used, however it is suggested that if these are used, they should be expressed as separate transcripts.

The next advance in the development of iRNA technology was to create transgenic animals that are capable of producing iRNA molecules from DNA templates and passing them on to their progeny. Providing heritable expression of iRNA molecules has become a principal research goal The production of cells and animals in which a gene function is effectively eliminated provides both valuable research tools and is invaluable to realize the potential of xenotransplantation, therapeutic cloning, and genetically enhanced agriculture.

In 2002, Hasuwa et al (FBBS Letters 532:227-230) reported a transgene-based RNAi system using an enhanced green fluorescent protean (eGFP) siRNA driven by a PolII promoter in mice and rate. Specifically, the promoter used was the HI promoter and the siRNA region contained seme sequence, a connecting sequence and an antisense sequence to eGFP. This construct allowed for the random integration of the DNA into the animals genome, which was expressed ubiquitously. fix 2003, Carnell et al (Nature Structural Biology 10(2) 91-92) repotted the germliue transmission of RNAi in mice via the random insertion of a transgene containing an \ exogenous promoter and siRNA sequence. Also in 2003, Kunath et al (Nature Biotechnology

May 2003 21: 559-561) reported the generation of knockdown murine embryonic stem(ES) cell lines with transgenic short-haiipin RNA (sKRNA) via random integration. A linearized transgene containing the HI RNA polymerase promoter, followed by sbRNA sequence (sense and antisense sequence separated by a seven base pair spacer), followed by five thymidines to teraafeate transcription was introduced via electroporation into the ES cells to achieve random integration of tire construct, resulting in a genetic null phenotype for the target gene. Kunaih et al. discuss the benefit of assaying gene function in vivo without gene targeting through siRNA technology. PCT Publication No. WO 03/059923 by Tranzyme, Inc. and Ozgene Pty., Ltd. describes the production of genetically modified animals using lentiviral vectors. In particular, the vectors described include selectable markers driven off of an exogenous promoter sequence for random integration. The publication describes the nucleotide sequence of interest contained in the gene transfer vector that includes a polynucleotide sequence, which expresses an KNA molecule capable of mediating KNA interference. WO 03/056022 by Oxford Biomedica, Ltd. describes methods of producing transgenic cells using lentiviral vectors for random insertion into the genome. The nucleotides that can be used include an siRNA and an exogenous promoter, such as a KNA polymerase promoter.

In 2003, it was reported that iKNA targeting strategies were developed to target two genes simultaneously with expression vectors under the control of exogenous promoters for random integration (Yu et al (2003) Molecular Therapy 7: 228-236, Anderson et al (2003) Oligonucleotides, 13: 303-312). Karlas et al (2004 Virology 325: 18-23) discloses inhibition of porcine endogenous retroviruses by iKNA using iKNA molecules corresponding to different parts of the PERV gene. The iKNA molecules were expressed as short hairpin RNAs under the control of an exogenous polymerase ΠΓ promoter in vitro for random integration. U.S. Patent Publication No. 2004/0045043 by Finney and Lofquist, entitled, "Compositions and Methods for Generating Conditional Knockouts" discloses methods to identify disease-associated genes, produce animal models of disease and identify drug candidates through conditional knockout strategies. The publication discloses the use of homologous recombination to engineer siRNA targets (not siRNA molecules) into endogenous genes.

While these initial strategies for providing animals with heritable transgenes have been developed, additional improvements are desired to further control protein expression and minimize adverse effects on the host cell or organism.

It is therefore an aspect of the present invention to provide improved methods to repress the expression of proteins in cells and animals.

In a further aspect, the present invention provides cells and animals with improved ability to repress the expression of a target protein in cells and animals and optimally with minimal disruption of other normal processes.

It is yet another aspect of the present invention, to provide new tools to accomplish the effective repression of proteins.

It is another aspect of the invention to apply new techniques to repress protein to specific areas of long felt need.

SUMMARY OF THE INVENTION

In a first embodiment, the present invention provides a method for producing a non-human transgenic cell, wherein the method comprises introducing into a cell, DNA templates which produce one or more iKNA molecules, wherein the one or more iRNA molecules hybridize to a conserved region of a gene family, wherein the conserved region is at least 90% identical among all members of the gene family.

In a further embodiment, the present invention provides a method for producing a nonhuman transgenic animal which heritably expresses one or more iRNA molecules, wherein the method comprises producing a transgenic cell, further comprising producing the animal via a method selected from: a. somatic cell nuclear transfer; b. microinjection of DNA into oocytes, zygotes or pre-implantation blastomeres; c. transfection of embryonic stem cells; d. sperm-mediated delivery of DNA; or e. transfecting embryos in vivo via the blood stream.

Improved techniques for the repression of expression of protein in cells and animals are provided. In one embodiment, the invention provides new methods and materials for the repression of expression of a protein that include the use of targeted insertion vectors which have a minimal effect on the homeostasis of the cell or animal. In particular, DNA templates that encode an iRNA to repress a target protein are provided that (i) use the endogenous regulatory elements of the cell, such as the endogenous promoter, (ii) are targeted into an intronic sequence of a gene, and/or (hi) do not disrupt the homeostasis of the cell. In a second embodiment, new iRNA molecules and DNA sequences encoding them are provided, as well as methods to produce the same. In one example, an iRNA molecule is provided in which both strands are complementary to a target mRNA (referred to herein as "cTarget") of a protein to be repressed, wbich can be in the form of a hairpin. In a third embodiment, iRNA molecules that regulate the expression of specific genes or family of genes that share a common, homologous sequence, such that the expression of the genes can be functionally eliminated, are provided.

In one aspect of the present invention, methods are provided to produce transgenic cells and animals that express iRNA molecules at a predetermined location, as well as the cells and animals produced thereby. In one embodiment, DNA templates or constructs, which produce iRNA molecules, that contain sequence that targets a particular location in the genome can be introduced into cells, such that the DNA templates are under the control of endogenous regulatory «dements of the cell, such as the promoter and/or other regulatory elements of the gene. Jn another embodiment, the DNA templates can be targeted such that expression of the iRNA molecule can be achieved without disrupting the endogenous gene function. In one embodiment, the DNA templates can be in the form of vectors. The vectors can he introduced into the cells directly, or linearized prior to introduction into the cell. In another embodiment, the DNA templates can be synthesized as oligonucleotides and introduced into cells. Ια one embodiment, the DNA templates can integrate into the genome of the cell -via targeted integration. The targeted integration can be via homologous recombination. The DNA templates can contain 5’ and 3’ targeting sequences that are homologous to the target gene to allow for targeted insertion. The DNA templates can be inserted via homologous recombination into, for example, a housekeeping gene such that tire expression of the iRNA molecule is under the control of the associated promoter of the housekeeping gene. Alternatively, the DNA templates can be inserted via homologous recombination into a gene that is only expressed in particular cells or organs such that the expression of the iRNA molecule is under the control of the associated promoter of the cell or organ specific gene. Such templates can be introduced into mammalian cells, such as human, porcine, ovine or bovine cells, bacterial cells, such as E. Coli, and/or yeast cells.

In other embodiments, the DNA teanplates/constructs used to produce the iRNA molecules can be designed to integrate into exons of the target gene. In another embodiment, the DNA templates used to produce the iRNA molecules can be designed to integrate into introns of the target gene, such as, for example, into a non-e$ssenfial location of an endogenous intron. The DNA templates can be targeted such that the endogenous promoter of the target gene directs transcription of the exogenous DNA template. In still further embodiments, the DNA templates used to produce the iRNA molecules can be embedded in engineered introns for integration into introns or exons of target genes. These engineered introns can be derived from any endogenous intron. In one embodiment, the endogenous intron can be reduced to its minimal functional components, hr another embodiment, restriction sites can be added into the engineered intron. In one embodiment, the restriction enzyme sites allow for placement of the DNA template into the engineered intron. In further embodiments, the synthetic introns can be inserted into endogenous exons or introns without disrupting the function of the endogenous gene.

In another embodiment, methods are provided to produce cells and animals in which interfering BNA molecules are expressed to regulate die expression of target genes. Methods according to this aspect of the invention can include: (i) identifying at least one iRNA sequence that is complementary to the target rtiRNA; (ii) manufacturing a DNA construct encoding die iRNA sequence; (iif) identifying a target endogenous nucleic acid sequences in a cell; (iv) introducing the DNA construct into the cell wherein the DNA construct further contains flanking sequence homologous to the endogenous target gene; and/or (v) expressing the DNA construct in the call under conditions such that the iRNA molecule binds to the target mRNA sequence, thereby regulatrog expression of one or more target mRNAs. In one emtodimjent, the present invention provides methods of producing non-human transgenic animals that heritably express iRNA molecules that regulate the expression of one or more target genes. In one embodiment, the animals can be produced via somatic cell nuclear transfer. The somatic ceil can be engineered to express the iRNA molecule by any of the techniques described herein.

In another aspect of the present invention, ds iRNA molecules are provided in which both strands are complementary to the niRNA target sequence (referred to herein as “cTarget”). Due to the intracellular processing of double stranded iRNA (ds iRNA) molecules, only one of the two strands of the molecule actually functions to inhibit the target mRNA. The present invention provides novel ds iRNA molecules in which both strands can be functional, i.e. can bind to the target RNA sequence. Prior to this discovery, the design of iRNA molecules was such that only one strand of the iRNA molecule was functional (i.e. typically one strand was substantially identical to the target sequence, or the “sense” sequence, and the other strand was the functional strand that was complementary to the target sequence, or the “antisense” sequence), and thus if the nonfunctional strand was processed in vivo, no inhibitory effect was generated.

In one embodiment, the ds iRNA molecules can contain a first cTarget strand of nucleotides, which hybridizes to a second cTarget strand sequence. In one embodiment, the cTarget strands can contain at least fifteen, sixteen, seventeen, eighteen, nineteen, twenty, twenty- one, twenty-two, twenty-three, twenty-four or twenty-five nucleotides. To obtain such iRNA molecules, segments of cTarget sequence must be evaluated to determine the portions which will hybridize to form a ds iRNA molecule. In one embodiment, segments of cTarget sequence at least 100,200 or 300 nucleotides in length can be analyzed to determine areas of self-hybridization. In one embodiment, these sequences can be entered into a computer program which detects areas of self-hybridization, such as, in one specific embodiment, the MFold softwares, as described in M. Zuker Mfold web server for nucleic acid folding and hybridization prediction. Nucleic Acids Res. 31 (13) 3406-15, (2003), [http://ww.bioMo^i.eduyapphcationshnfold/old/riia/fi»xnl.cgi]. In one embodiment^ the cTarget sequences can be complementary to the same target sequence. In another embodiment, the cTarget sequences can be complementary to different target sequences, ha a further embodiment, the ds iRNA molecule can be palindromic cTarget sequences, in which both strands are identical or functionally identical. In one embodiment, a cTarget sequence cm be analyzed, to identify palindromic sequences, for example, through the use of a computer program, such as DNA Strides:.

In other embodiments, DNA templates are provided, which produce ds iKNA molecules that are two strands of cTarget sequence. 3h one embodiment, DNA templates are provided that produce iSNA precursors. In one embodiment, a spacer nucleotide sequence can separate the two cTarget sequences. In another embodiment, a nucleotide sequence is provided that contains a first strand complementary to a target and a second strand complementary to a target, which substantially hybridizes to the first strand and a spacer sequence connecting the two strands. In one embodiment, the spacer can form a loop or hairpin structure. Such hairpins can be cleaved inside the cell to provide a duplexed mKNA containing the two stems. In one embodiment, the spacer nucleotide sequence can be at least 2, 3, 4, 5, 6, 7, 8, 9, 10 or 15 nucleotides in length. In another embodiment, the spacer sequence can contain nucleotides that form a loop structure, such as a mir30 loop structure, such as disclosed in Seq Π> No 4 or any of the sequences described herein. In one embodiment the loop structure can contain a first nucleotide sequence, such as at least two, three, four or five nucleotides, followed by a second nucleotide sequence, such as at least two, three, four or five nucleotides, followed by a third nucleotide sequence that substantially hybridizes to the first sequence of nucleotides, followed by a fourth string of nucleotides, such as two, three, four or five nucleotides, thereby forming a two loop structure. In one embodiment, this two loop structure can serve as a substrate for a nuclease, such as Drosha.

In a further embodiment, an additional nucleotide sequence can flank the two cTarget strand sequences, hi one embodiment, the additional nucleotide sequence can be at least three, four, five, ten or fifteen nucleotides 5’ and 3’ to the cTarget strands. In one embodiment, a stem sequence can be 5’ and 3' to die cTarget strand sequences. In one embodiment, the stem sequence can contain at least four, five, six or seven nucleotides. The 51 stem sequence can contain a first, second and third nucleotide sequence upstream of the first cTarget strand. The 3’ stem sequence can contain a fourth, fifth and sixth nucleotide sequence, wherein the fifth nucleotide sequence substantially hybridizes to the second nucleotide sequence of the 5’ stem and the fourth and sixth nucleotide sequences do not hybridize to the first and third sequence of the 5’ stem. The stem sequence can be a air30 stem sequence, such disclosed any of the sequences described herein..

In another embodiment, the additional nucleotide sequence can be a cloning site 5’ and/or 3’ to the cTarget sequence. In one embodiment, the cloning site can be 5’ and/or 3’ of the stem sequence. The cloning site can contain engineered restriction enzyme sites to allow for cloning and splicing of nucleotide sequences within larger sequences.

In one specific embodiment, the DNA template can produce an RNA molecule with at least two of the following components wherein the Target complement A and Target complement B will be processed by foe cell to form a ds iRNA molecule. One nonlimiting iUoustrative embodiment is depicted bdow:

In an additional embodiment, inhibitory KNAa can be constructed by addition of individual inhibitory RNAs into an array or cluster. In one embodiment, a cluster of individual hairpin iRNAs joined in tandem with or without linker sequence is provided. In one embodiment, this structure can have radial symmetry (see, for example, Figure 2). These radial iSNA molecules can exhibit radial symmetry in structure without having radial symmetry in sequence. In an alternative embodiment, duplex RNAs can be joined with a variety of spacer sequences to produce a structure that is nearly linear or curved (see, for example, Figure 3). These structures can be produced by linking a series of oligonucleotides with or without spacer sequence and then adding the complement sequence of these oligonucleotides in foe reverse order, again with ox without linker sequence. In additional embodiments, these structural strategies can be combined to produce complex structures. In other embodiments, radial iRNAs and linear clustered iRNAs can mediate targeted inhibition of mRNA via small interfering RNAs.

In other embodiments, methods are provided to optimize the hybridization of foe two cTarget strands, or any sequences in which hybridization is desirable. Cytosine resides in putative sequences can be replaced with uracil residues, since non-Watson-Crick base pairing is possible in KNA molecules. These uracil residues can bind to either guanine or adenosine, thereby potentially increasing the degree of hybridization between the strands.

In a further aspect of the present invention, iRNA molecules that regulate the expression of specific genes or family of genes are provided, such that the expression of tire genes can be functionally eliminated. In one embodiment, at least two iRNA molecules are provided that target the same region of a gene. In another embodiment, at least two iRNA molecules are provided that target at least two different regions of the same gene. In a further embodiment, at least two iRNA molecules are provided that target at least two different genes. Additomal embodiments of the invention provide combinations of the above strategies for gene targeting.

In one embodiment, the iRNA molecules can be the same sequence. In an alternate embodiment, the iRNA molecules can be different sequences. In another embodiment, the iRNA molecules can be integrated into either the same or different vectors or DNA templates. In one embodiment, the iRNA molecules within the vector or DNA template are operably linked to a promoter sequence, such as, for example, a ubiquitously expressed promoter or cell-type specific promoter. In another embodiment, the iRNA molecules within the vector or DNA template are not under the control of a promoter sequence. In a further embodiment, these vectors or DNA templates can be introduced into a cell, hi one embodiment, the vector or DNA template can integrate into the genome of the celL The integration into the cell can either be via random integration or targeted integration. The targeted integration can be via homologous recombination.

In other embodiments, at least two iRNA molecules are provided wherein the families of one or more genes can be regulated by expression of the iRNA molecules. In another embodiment, at least three, four or five iRNA molecules are provided wherein the families of one or more genes can be regulated by expression of the iRNA molecules. The iRNA molecule can be homologous to a conserved sequence within one or more genes. The family of genes regulated using such methods of the invention can be endogenous to a cell, a family of related viral genes, a family of genes that are conserved within a viral genus, a family of related eukaryotic parasite genes, or more particularly a family of genes from a porcine endogenous retrovirus. In one specific embodiment, at least two iRNA molecules can target tire at least two different genes, which are members of the same family of genes. The iRNA molecules can target homologous regions within a family of genes and thus one iRNA molecule can target the same region of multiple genes.

The iRNA molecule, for example, can be selected from, but are not limited to the following types of iRNA: antisense oligonucleotides, ribozymes, small interfering RNAs (sERNAs), double stranded RNAs (dsRNAs), inverted repeats, short hairpin RNAs (shRNAs), 'small temporally regulated RNAs, and clustered inhibitory RNAs (ciRNAs), including radial clustered inhibitory RNA, asymmetric clustered inhibitory RNA, linear clustered inhibitory RNA, and complex or compound clustered inhibitory RNA.

In another embodiment, expression of iRNA molecules for regulating target genes in mammalian cell lines or transgenic animals is provided such that expression of the target gene is functionally eliminated or below detectable levels, ie. the expression of the target gene is decreased by at least about 70%, 75%, 80%, 85%, 90%, 95%, 97% or 99%. in another embodiment of this aspect of the present invention, methods are provided to produce cells and animals in which interfering RNA molecules are expressed to regulate the expression of target genes. Methods according to this aspect of the invention can comprise, for example: identifying one or more target nucleic acid sequences in a cell; obtaining at least two iRNA molecules that bind to the target nucleic acid sequence(s); introducing the iRNA molecules, optionally packaged in an expression vector, into the cell; and expressing the iKNAs in the cell under conditions such that the iKNAs bind to the target nucleic acid sequences, thereby regulating expression of one or more target genes. In one embodiment, the present invention provides methods of producing non-human transgenic animals that heritably express at least two iRNA molecules that regulate the expression of one or more target genes, ϊα one embodiment, the animals can be produced via somatic cell nuclear transfer. The somatic cell can be engineered to express the iRNA molecule by any of the techniques described herein.

In other embodiments, the present invention also provides methods for the expression of at least two iRNA molecules in a cell or a transgenic animal, where the iRNA targets a common location within a family of genes. Such methods can include, for example: identifying one or more target nucleic acid sequences in the cell that are homologous regions within a family of genes; preparing at least two iRNA molecules that bind to the target nucleic acid sequence(s); introducing the iRNA molecules, optionally packaged in an expression vector, into the cell; and expressing iKNAs in the cell or animal under conditions such that the iRNA molecules bind to the homologous region within die gene family.

The present invention also provides transgenic non-human animals produced by Ihe methods of the invention. The methods of the invention are useful for example for the production of transgenic non-human mammals (e.g. mice, rats, ungulates, sheep, goats, cows, porcine animals, rabbits, dogs, horses, males, deer, cats, monkeys and other non-human primates), birds (particularly chickens, ducks, and geese), fish, reptiles, amphibians, worms (e. g. C. elegans), and insects (including hut not limited to, Mosquitos, Drosophila, Trichoplusa, and Spodoptera). While any species of non-human animal can be produced, in one embodiment the non-human animals are transgenic ungulates, including pigs. The present invention also provides cells, tissues and organs isolated from such non-human transgenic animals. hi embodiments of the present invention, endogenous genes that can be regulated by the expression of at least two iRNA molecules include, but are not limited to, genes required for cell survival ox cell replication, genes required for viral replication, genes that encode an immunoglobulin locus, for example, Kappa light chain, and genes that encode a cell surface protein., for example, Vascular Cell Adhesion Molecule (VGAM) and other genes important to the structure and/or function of cells, tissues, organs and animals. The methods of the invention can also be used to regulate the expression of one or more non-coding SNA sequences in a transgenic cell or a transgenic animal by heritable transgene expression of interfering RNA. These non-coding RNA sequences can be sequences of an ENA virus genome, an endogenous gene, a eukaryotic parasite gene, or other non-coding ENA sequences that are known in the art and that will he familiar to the ordinarily skilled artisan.

In an exemplary embodiment of the present invention, porcine endogenous retrovirus (PERV) genes can be regulated by the expression of at least two iRNA molecules such that the expression of the PERV virus is functionally eliminated or below detection levels. PERV refers to a family of retrovirus of which three main classes have been identified to date: PERV-A (Genbahk Accession No. AF038601), PERV-B (EMBL Accession No. PERY17013) and PERV-C (Genbank Accession No. AF038600) (Patience et ai 1997, Akiyoshi et al 1998). The gag andpol genes of PERV-A, B, and C are highly homologous, it is the env gene that differs significantly between the different types of PERV (eg., PERV-A, PERV-B, PERV-C). PERV-D has also recently been identified (see, for example, U.S. Patent No 6,261,806).

In one embodiment, iRNA directed to the PERV virus can decrease the expression of PERV by at least about 70%, 75%,80%, 85%, 90%, 95%, 97% or 99%, or alternatively, below detectable levels. To achieve this goal, the present invention provides at least two iRNA molecules that target the same sequence within the gag, pol or env region of the PERV genome. Further, at least two iRNA molecules are provided that target different sequences within the gag, pol or env regions of the PERV genome. Still further, at least two iRNA molecules are provided that each target different regions (i.e. either gag, pol or <mv) of the PERV genome. Additionally;, multiple iRNA molecules are provided that combine these different targeting strategies, for example: at least two SKA. interference molecules directed · to the gag region of PERV; at least two SNA interference molecules directed to the pol region of PERV; and at least two SKA. interference molecules directed to the env region of PERV axe provided to target die PERV gene.

The present invention also provides ungulate, and particularly, porcine animals, as well as cells, tissues and organs isolated from non-human transgenic animals in which the expression of PERV is functionally eliminated via the expression of at least two iRNA molecules. In certain such embodiments, they are obtained from transgenic pigs that express one or more interfering RNAs that interfere with the porcine endogenous retrovirus gene, a family member of the porcine endogenous retrovirus gene or a member of a subset of the porcine endogenous retrovirus gene family.

BRIEF DESCRIPTION OP THE DRAWINGS

Figure 1 illustrates an example of a mechanisms by which an interfering RNA can mediate targeted destruction of cellular ENA. In this model, an expression vector includes nucleic acid sequence encoding an RNA sense strand (black box) and antisense strand (gray box) in an inverted sequence are operably linked to a single promoter (white box). Following transcription of the construct, the sense strand binds to its complimentary antisense strand, resulting in a double stranded, ‘hairpin* RNA molecule (dsRNA). The dsKNA is subsequently processed by an enzyme (Dicer, also known as RNAse ID) to produce a small interfering RNA (siRNA). One siRNA Ihfin. associates with an RNA-induced silencing complex (RISC) and with the target cellular mRNA The binding of the cellular mRNA to the RISC induces cleavage of the mRNA, thereby limiting the functional expression of a specified gene product

Figure 2 illustrates an example of a mechanism by which clustered inhibitory RNA (ciRNA) can mediate the destruction of cellular RNA hi this model, an expression vector includes a pattern of nucleic acid sequences encoding multiple complimentary RNA sense strands (black boxes) and inverted antisense strands (gray boxes). This pattern can be operably linked to a single promoter (white box). Following transcription, the ciRNA transcript can autonomously fold so that each sense strand can bind to a complimentary antisense strand. This folding can result in a radially arrayed, double stranded RNA complex •with a hairpin structure at each, outer axis. This complex, can be processed by an enzyme (Dicer, also known as RNAse EOT), producing multiple small interfering ENA (siENA) molecules. The resultant siENA molecules can associate with an RhiA.-ind.uced silencing complex (RISC) and with multiple target mRNA sequences. The binding of the cellular mRNA to the RISC induces cleavage of the mENA sequsnce(s), thereby eliminating the functional expression of one or more specified gene produces). figure 3 illustrates another potential mechanism by which clustered inhibitory ENA (ciENA) could mediate tire targeted destruction of cellular RNA. In this model, an expression vector includes nucleic add sequences encoding multiple complimentary RNA sense strands (black box) and inverted antisense strands (gray box), operably finked to a single promoter (white box). Following transcription, the ciRNA transcript autonomously folds so that each sense strand can bind to a complimentary antisense strand. The resulting structure can be a linear, double stranded ENA complex, coutaiciag at least one hairpin turn. The linear, double stranded ciRNA complex can then be processed by an enzyme (Dicer, also known as RNAse HI), producing multiple small interfering ENA (siENA) molecules. The resultant siENA molecules can associate with an RNA-induced silencing complex (RISC) and with multiple target mRNA sequences. The binding of tire cellular mENA to the RISC induces cleavage of the mENA sequence(s), thereby eliminating the functional expression of one or more specified gene produces).

Figure 4 is a representation of molecules of the present invention. The molecules of the invention contain one or more "sets” of iENA sequences. These sets can comprise at least one iRNA sequence targeted to a single region of a target gene (Set 1), multiple regions of a target gene (Set 2), or regions on multiple genes (Set 3). The embodiments are further described and exemplified in the text.

Figure 5 is a graphical depiction of a representative vector promoter driven vector (top) and a graphical representation of a representative promoteriess vector which can be used in the practice of the invention.

Figure 6 is a representation of the process of “promoter trap” (top panel) and “gene trap” (bottom panel) technologies described in the text Jh the top panel, the iENA vector includes one or more iRNA sequences (black boxes) and a 5’ and 3’ sequence homologous to one or more exon sequences of a desired gene (diagonally striped boxes). The figure shows the homologous sequences recombining to provide a final gene with an iENA insert, fir the lower panel, the gene trap vector is shown containing one or more RNA sequences, sequences homologous to an intron region in a gene (striped boxes), and a splice acceptor (SA) site immediately upstream of the promoterless iRNA sequence insert. The integration of the iRNA insert in an intron can lead to a fusion transcript with the upstream exon of the gene upon transcription.

Figure 7 is a graphical representation of an analysis of die alleles of four genes. Gene 1 is shown to have three alleles. Gene 2,3, and 4 are shown to have four alleles each. Boxes with the same pattern, within a region, represent sequences that are identical. Boxes with different patterns within a region represent different sequences within that region. Region 1 differs in sequence between all genes and alleles except for Gene 1, allele A and B. Region 2 is conserved among all family members. Only two· sequences are found in region 3. Likewise, only two sequences are found, in region 4. Seven sequences are found in region 5. Region 6 is not conserved among any family members. Effective targeting of region 2 provides suppression of ah family members. Effective targeting of one of the two sequences found in region three specifies a subset of genes. Sets of targeting transgenes can be assembled to repress subsets of alleles or genes.

Figure 8 shows an analysis of a portion of PERV env genes. The region spanning bases 6364 to 6384 is homologous between all family members shown. Two polymorphisms axe shown for the dinucleotide at bases 6400 and 6401. Two transgenes are required to effectively repress the shown genes whan targeting regions that include this dinucleotide, The region spanning bases 6408 to 6431 represent three polymorphisms. Likewise regions that include base 6385 represent three polymorphisms. Single transgenes that target one of the three polymorphism in tripolymoiphic regions differentiate a subset of the shown sequences. A set of three transgen.es, each targeting a different polymorphism in the tripolymoiphic regions is required to target all shown sequences.

Figure 9 illustrates representative inhibitory KNA targets. An 86 base consensus for a semi-conserved region of PERV is shown on the first hue. Sixty-eight potential 19 base targets for inhibitory RNA within this sequence are shown on subsequent lines. Targets can be between 17 and 35 bases in length. This process can be reiterated for targets of 17-35 bases and can be applied to any region, protein coding or non-coding, included within any complete or partial PERV genome. All PERV sequences are potential targets. Line 1, PERV sequence; lines 2-69, potential targets.

Figure 10 illustrates the identification of potential targets that share significant homology with non-targeted genes. RNA sequence of target genes are screened for homology to non-targeted KNAs, A 19 base region of an unknown porcine expressed sequence (Genbank entry BD05054) is significantly homologous to a region of semi-conserved PERV sequence (shown in black face bold type). Though potential target regions with significant homology to non-targeted RNAs can prove useful, such, target regions are excluded in initial target screens to reduce the risk of severely down-regulating unintended gene products. Line 1, PERV sequence; lines 2-69, potential targets; line 70, unknown expressed porcine sequence; lines 36-56, excluded targets.

Figure 11 represents the configuration of an inhibitory SNA designed for die potential target sequence of Figure 9 fhatis listed first (Line 2, Figure 3). Wherein “N” refers to any nucleotide and “Y” refers to any integer greater than or equal to zero. Each portion of non-specified sequence, (Νγ), can be homopolymeric or can be composed of non-identical bases, in addition, any continuous stretch of non-specified sequence, (Ny), can provide additional functions such as but not limited to encoding protein, providing signals for stability or increased half-life, increasing the length of palindromic sequence, providing signals and functions for splicing, or folding into particular structures.

Figure 12 represents the illustrative sequence for radial clustered inhibitory RNA, asymmetric bubble ciRNA, linear ciRNA, and complex ciRNA to a targeted PERV gag consensus sequence.

Figure 13 represents a representation of a cloning strategy to insert portions of a gene into a vector.

DETAILED DESCRIPTION OF THE INVENTION

Improved techniques for the repression of expression of protean in cells are provided. In one embodiment, the invention provides new methods and materials for the repression of expression of a protein that include the use of targeted insertion vectors which have a minimal effect on the homeostasis of the cell. In particular, DNA templates that encode an iRNA to repress a target protein axe provided that ¢) use the endogenous regulatory elements of the cell, such as the endogenous promoter, (h) are targeted into an intronic sequence of a gene, and/or (fii) do not disrupt the homeostasis of the cell. Ια a second embodiment, new iRNA molecules and DNA sequences encoding them are provided, as well as methods to produce the same. In one example, a iRNA molecule is provided in which both strands are complementary to a target mRNA (cTarget) of a protein to be repressed, which can be is in the form of a hairpin, fit a third embodiment, iRNA molecules that regulate Ihe expression of specific genes or family of genes that share a common, homologous sequence, such that the expression, of the genes can be functionally eliminated are provided.

Unlike gene knockout technology, RNA interference (RNAi) is a genetically dominant phenomenon, i.e., the transgene does not need to be rendered homozygous. In addition, RNA interference can be directed against genes that may or may not reside in the genome.

In one aspect of the present invention, methods are provided to produce transgenic cells and animals that express iKNA molecules at a predetermined location, as well as the cells and animals produced thereby. In one embodiment, DNA templates, which produce IRNA molecules, that contain sequence that targets a particular location in the genome can be introduced into cells, such that the DNA templates are tinder control of the endogenous regulatory dements of the cell, such as the promoter and/or other regulatory elements of the gene. In another embodiment, the DNA templates can be targeted such that expression of the iRNA molecule can be achieved without disrupting the endogenous gene function. In one embodiment, the DNA templates can be in the form of vectors. The vectors can be introduced into the cells directly, or linearized prior to introduction into the cell. In another embodiment, the DNA templates can be synthesized as oligonucleotides and introduced into cells. In one embodiment, the DNA templates can integrate into the genome of the cell via targeted integration. The targeted integration can be via homologous recombination. The DNA templates can contain 5’ and 3’ targeting sequence that is homologous to the target gene to allow for targeted insertion. The DNA templates can be inserted via homologous recombination into, for example, a housekeeping gene such that the expression of die iRNA molecule is under the control of the associated promoter of the housekeeping gene. Alternatively, the DNA templates can he inserted via homologous recombination into a gene that is only expressed in particular cells or organs such that the expression of the iRNA molecule is under fee control of fee associated promoter of fee cell or organ specific gene. Such templates can be introduced into mammalian cells, such as human, porcine, ovine or bovine cells, bacterial cells, such as E. Coli, and/or yeast cells.

In another aspect of the present invention, ds iRNA molecules are provided in which both strands are complementary to the mENA target sequence (cTarget). Due to the intracellular processing of double stranded iRNA (ds iRNA) molecules, only one of fee two strands of fee molecule actually functions to inhibit fee target mRNA. The present invention provides novel ds iRNA molecules in which both strands can be functional, Le. can bind to the target RNA sequence. Prior to this discovery, the design of iRNA molecules was such that only one strand of the CRNA. molecule was functional (Le. typically one strand was substantially identical to die target sequence, or the “sense” sequence, and the other strand was tire functional strand that was complementary to the target sequence, or the “antisense” sequence), and thus if the nonfunctional strand was processed in vivo, no inhibitory effect was generated.

In a further aspect of the present invention, iRNA molecules that regulate the expression of specific genes or family of genes are provided, such that the expression of the genes can be functionally eliminated. In one embodiment, at least two iRNA molecules are provided that target the same region of a gene. In another embodiment, at least two iRNA molecules are provided that target at least two different regions of the same gene, hi a further embodiment, at least two iRNA molecules are provided that target at least two different genes. Additional embodiments of the invention provide combinations of the above strategies for gene targeting

In an exemplary embodiment of the present invention, porcine endogenous retrovirus (PERV) genes can be regulated by the expression of at least two iRNA molecules such that the expression of the PERV virus is functionally eliminated or below detection levels. PERV refers to a family of retrovirus of which three main classes have been identified to date: PERV-A (Genbank Accession No. AF038601), PERV-B (EMBL Accession No. PBRY17013) and PERV-C (Genbank Accession No. AF038600) (Patience et si 1997, AMyoshi et al 1998). The'gag andpol genes of PERV-A, B, and C are highly homologous, it is the env gene that differs between the different types of PERV (eg., PERV-A, PERV-B, PERV-C). PERV-D has also recently been identified (see, for example, U.S. Patent No 6,261,806). L Definitions

Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art

As used herein, the term“animal" is meant to include any animal, including but not limited to non-human mammals (including, but not limited to, pigs, sheep, goats, cows (bovine), deer, mules, horses, monkeys and other non-human primates, dogs, cats, rats, mice, rabbits), birds (including, but not limited to chickens, turkeys, ducks, geese) reptiles, fish, amphibians, worms (e.g. C. elegans), insects (including but not limited to, Drosophila, Trichoplusa, and Spodoptera). A "transgenic animal" is any animal containing one or more

ceils bearing genetic information received, directly or indirectly, by deliberate genetic manipulation at the subcelhilar level. A "transgenic cell" is any cell bearing genetic information received, directly or indirectly, by deliberate genetic manipulation at the subcellular leveL

The term "ungulate” refers to hoofed mammals. Artiodactyls are even-toed (cioven-hooved) ungulates, including antelopes, camels, cows, deer, goats, pigs, and sheep.

Perissodactyls are odd toes ungulates, which include horses, zebras, rhinoceroses, and tapirs. As used herein, the terms "porcine", "porcine animal", "pig" and "swine" are generic terms referring to the same type of animal without regard to gender, size, or breed.

As used herein, the term "heritable," particularly when used in the context of "heritable gene," "heritable trait," 'heritable characteristic," "heritable iRNA", means that the unit, e.g. the gene, trait, characteristic, iRNA, etc., are capable of being inherited or of passing by inheritance.

As used herein, the term "regulation of gene expression" refers to the act of controlling the ability, timing, level, manner or cell-type of transcription of a gene. Regulation can result in increased expression of a gene, decreased expression of a gene or maintenance of expression of a gene, as described herein.

As used herein, except where the context requires otherwise the term ‘comprise’ and variations of the term, such as ‘comprising’, ‘comprises’ and ‘comprised’, are not intended to exclude other additives, components, integers or steps. II. iRNA Molecules A. iRNA Design

In one aspect of the present invention, ds iRNA molecules are provided in which both strands are complementaiy to the target sequence (cTarget). Due to the intracellular processing of double stranded iRNA (ds iRNA) molecules, only one of the two strands of the molecule actually functions to inhibit the target mRNA. The present invention provides novel ds iRNA molecules in which both strands can be functional, i.e. can bind to the target RNA sequence. Prior to this discovery, the design of iRNA molecules was such that only one strand of the iRNA molecule was functional (i.e. typically one strand was substantially identical to the target sequence, or the "sense" sequence, and the other strand was the functional strand that was complementary to the target sequence, or the "antisense" sequence), and thus if the nonfunctional strand was processed in vivo, no inhibitory effect was generated.

Tfrufop-enoiis ίΚΝΑ Processing.

Micro-RNAs (mdRNAs) are small endogenous RNAs involved in post-transcriptional regulation of genes. One such miRNA (mir30) is transcribed as a large transcript (pxindr30) that processed via Drosha into a smaller hairpin structure (pre-mir30) that is exported from the nucleus. In the cytoplasm, pre-mir30 is further processed by Dicer to yield mature mir30. This process is known in the art (see for example, Zeng Y, Cullen BR. Structural requirements for pre-microKNA binding and nuclear export by Exportin 5. Nucleic Acids Res. 2004 Sep 08;32(16):4776-85; Zeng Y, Cullen BR. Sequence requirements fox micro RNA processing function in human cells. RNA. 2003 Jan; 9(1): 112-23). The MFold (M.

Zuker. Mfold web server for nucleic acid folding and hybridization prediction. Nucleic Adds Res. 31 (13) , 3406-15, (2003)

Jhttp^/ww.bionifo.TpLedu/^Hcations/mfold/old/nWfonnl.cgi]) putative predicted structure of a portion ofpri-mir30 is shown below.

The MFold putative predicted structure of the pre-mir3 0 Drosha cleavage product follows:

The nucleotide sequence of the above sequence is ΠΓΤ7Α AACAUCCUCGACUGGAA GCUGUGAAGCC ACAGAUGGGCUUUCAGUCGGAUGUUUGCAGC (Seq ID No 1). A imntmal pri-mir30 Drosha substrate has been described for in vitro cleavage (Lee Y, Aha C, Han J3 Choi H, Kim J, Yim f, Lee J, Provost P, Radmaik 0, Kim S, Kim YN. The nuclear KNase m Drosha initiates microRNA processing. Nature. 2003 Sep25;425(6956):415-9) The putative predicted structure of this substrate follows:

The nucleotide sequence of the above sequence is UGCUGUUGACAGUGAGCGACUGUAAACAUCCQCGACUGGAAGCUGUGAAGCCA CAGAUGGGCUUUCAGXJCGGAUGIJUIIGCAGCUGCCUACUGCCUCGGACUUCAAG GG(SeqIDNo2). A minimal pri-mir30 Drosha substrate has also been described for in vivo cleavage in the context of an irrelevant mKNA (Zeng Y, Wagner EJ, Cullen BR Both natural and designed micro RNAs can inhibit the expression of cognate mRNAs when expressed in human cells. Mol Cell. 2002 Jim;9(6):1327~33; Zeng Y, Cullen BR. Sequence requirements for micro KNA processing and function in human cells. RNA 2003 Jan; 9(1):112-23). The putative predicted structure of this substrate follows:

The nucleotide sequence of the above sequence is GCGACUGUAAACAUCCUCGACUGGAAGCUGUGAAGCCACAGAUGGGCUUUCAG UCGGAUGUUUGCAGCUGC (Seq ID No 3).

Additionally, it has been shown that the active portions of nriKNAs can be replaced to generate novel hairpins with siRNA activity (Zeng Y, Wagner EJ, Cullen BR. Both natural and designed micro RNAs can inhibit the expression of cognate mRNAs when expressed in human cells. Mol Cell. 2002 Jun;9(6):1327-33;; Boden D, Pusch O, Silbexmann R, Lee F, Tucker L, Ramratnam B. Enhanced gene silencing of HIV-1 specific siRNA using microRNA designed hairpins. Nucleic Adds Res. 2004 Feb 13;32(3) :1154-8). iRNA Molecules Ια one embodiment, the ds iRNA molecules can contain a first cTarget strand of nucleotides, which hybridizes to a second cTarget strand sequence. The cTarget strands can contain at least fifteen, sixteen, seventeen, eighteen, nineteen, twenty, twenty- one, twenty-two, twenty-three, twenty-four, twenty-five, twenty-six, twenty-seven, twenty-eight, twenty-nine, thirty, thirty-one, thirty-two, thirty-three, thrirty-four, thirty-five, thirty-six, thirty-seven, thirty-eight, thirty-nine, forty, forty-one, forty-two, forty-three, forty-four, forty-five, forty-six, forty-seven, forty-eight, forty-nine, or fifty nucleotides, in particular, nineteen to thrity-two nucleotides, or twenty-one to foewnt-foree nucleotides in length.

Methods are also provided to obtain iRNA molecules that are a first cTarget strand of nucleotides, which hybridizes to a second cTarget strand sequence. A complementary sequence to the target sequence (cTarget) is first determined and then segments of cTarget sequence can be evaluated to determine the portions of which will hybridize together to form a ds iRNA molecule. In one embodiment, segments of cTarget sequence at least 25, 50, 100, 200 300, 400 or 500 nucleotides in length can be analyzed to determine areas of self-hybridization. In one embodiment these sequences can be enetered into a computer program which detects areas of self-hybridization, such as, in one specific embodiment, the MFold software, as described in M. Zuker Mfold web server for nucleic add folding and hybridization prediction. Nucleic Acids Res. 31 (13) 3406-15, (2003), ]http://www.bioMo.ipi.edu/applications/mfold/old/xna/fonnl.cgi].

Jh other embodiments, DNA templates axe provided, which produce ds iRNA molecules that are two strands of cTarget sequence. In one embodiment, DNA templates axe provided that produce iRNA precursors. In one embodiment, a spacer nucleotide sequence can separate the two cTarget sequences. In another embodiment, a nucleotide sequence is provided that contains a first strand complementary to a target and a second strand complementary to a target; which substantially hybridizes to the first strand and a spacer sequence connecting the two strands, hr one embodiment, the spacer can form a loop or hairpin structure. Such hairpins can be cleaved inside the cell to provide a duplexed mRNA containing the two stems. In one embodiment; the spacer nucleotide sequence can be at least 2,3,4, 5,6,7, 8,9,10,11, 12,13,14, 15, 16, 17,18,19,20,25, 30,40 or 50 nucleotides in length. In another embodiment, foe spacer sequence can contain nucleotides that form a loop structure, such as a mir30 loop structure. The mir30 loop structure can contain at least foe following sequence: GUGAAGCCACAGAUG (Seq ID No 4), or as indicated in any of foe sequences listed herein. In one embodiment foe loop structure can contain a first nucleotide sequence, such as at least two, three, four or five nucleotides, followed by a second nucleotide sequence, such as at least two, three, four or five nucleotides, followed by a third nucleotide sequence that substantially hybridizes to the first sequence of nucleotides, followed by a fourth string of nucleotides, such as two, three, four or five nucleotides, thereby forming a two loop structure. M one embodiment, this two loop structure can serve as a substrate for a nuclease, such as Drosha.

In a farther embodiment, additional nucleotide sequence can flank the two cTarget strand sequences. The additional nucleotide sequence can be at least three, four, five, ten or fifteen nucleotides 5’ and 3’ to the cTarget strands. In one embodiment, a stem sequence can be 5’ and 3’ to the cTarget strand sequences. The stem sequence can contain at least four, five, six or seven nucleotides. The 5’ steam, sequence can contain a first, second and third nucleotide sequence upstream of the first cTarget strand. The 3’ stem sequence can contain a fourth, fifth and sixth nucleotide sequence, wherein the fifth nucleotide sequence substantially hybridizes to the second nucleotide sequence of the 5’ stem and the fourth and sixth nucleotide sequences do not hybridize to the first and third sequence of the 5’ stem. The stem sequence cam be a mir30 stem sequence, such as illustrated in any of the sequences listed herein, such as Seq ID No 5.

In another embodiment, the additional nucleotide sequence can be a cloning site 5’ and/or 3’ to the cTarget sequence. In one embodiment, the cloning site can be 5’ and/or 3’ of the stem sequence. The cloning site cm contain engineered restriction enzyme sites to allow for cloning and splicing of nucleotide sequences within larger sequences.

In one specific embodiment, the DMA template can produce an RNA molecule with at least two of the following components, as illustrated below, wherein the Target complement A and Target complement B will be processed by the cell to form a ds iKNA molecule:

The nucleotide sequence for the above sequence is GAUCUGCGCUGACUGUAUAUCUUGAUCAGGCUGUGAAGCCACAGAUGAGCUU GGGGAGAAUAUAGUCGAUGCUGAUC (Seq ID No 5).

Id. one embodiment, the DNA template can produce a Drosha substrate that is processed into a junctional iRNA molecule.

In one embodiment, the cTarget sequences can be complementary to the same target sequence. In another embodiment, the cTarget sequences can be complementary to different target sequences. In a further embodiment, the ds iRNA molecule can be palindromic cTarget sequences, in which both strands are identical or functionally identical. Ια one embodiment, a cTarget sequence can be analyzed to identify palindromic sequences, for example, through the use of a computer program, such as DNA Strider.

In other embodiments, methods are provided to optimize the hybridization of the two cTarget strands, or any sequences in which hybridization is desirable. Cytosine resides in putative sequences can be replaced with uracil residues, since non-Watson-Crick base pairing is possible in RNA molecules. These uracil residues can bind to either guanine or adenosine, thereby potentially increasing the degree of hybridization between the strands.

Targeting two sites of anmRNA simultaneously

In one embodiment, the cTarget sequences can be complementary to the same target sequence. By using the sequence that is complementary to an mRNA, one can design iRNA molecules, such as hairpins, in which both strands of the stem are complementary to the target mJRNA. In one embodiment, such hairpins can serve as a Drosha substrate and the resulting structure can be cleaved to produce two strands, each of which is capable of exerting an inhibitory effet on the target mRNA.

The complementary sequence to the target sequence (cTarget) is first determined and then segments of cTarget sequence can be evaluated to determine the portions of which will hybridize together to form a ds iRNA molecule. In one embodiment, segments of cTarget sequence at least 25, 50, 100, 200 300, 400 or 500 nucleotides in length can be analyzed to determine areas of self-hybridization. In one embodiment, these sequences can be entered into a computer program which detects areas of self-hybridization, such as, in one specific embodiment, the MFold software, as described in M. Zuker Mfold web server for nucleic acid folding and hybridization prediction. Nucleic Acids Res. 31 (13) 3406-15, (2003), [http^/www.bioinfo .ipi.edu/applications/mfold/old/ma/fbrml. c gi]. Areas of self hybridization can then "be identified and tested for its effct in the cell.

Targeting two mRNAs simultaneously hot addition to the strategies describe above, one can combine the antisense strands of portions of two mRNAs to create a single iRNA molecule, such as a hairpin iRNA molecule, that potentially targets two mRNAs. Complementary sequence to each of the target sequences (cTaiget) can first be determined and then segments of each cTarget sequence can be spliced together. For example, at least 25, 50, 100, 200 300, 400 or 500 nucleotides of cTarget to a first target (cTarget 1) can be joined with at least 25, 50,100, 200 300,400 or 500 nucleotides of cTarget to a second target (cTarget 2). This sequence of nucleotides can be evaluated to determine the portions of which will hybridize together to form a ds iRNA molecule. In one embodiment, these sequences can be entered into a computer program which detects areas of self-hybridization, such as, in one specific embodiment, the MFold software, as described in M. Zuker Mfold web server for nucleic acid folding and hybridization prediction. Nucleic Acids Res. 31 (13) 3406-15, (2003), [http://www.bioinfojpi.edu/appHcatioris/mfold/old/rna7fomil .cgij. Areas of hybridization between cTarget 1 and cTarget 2 can then be identified and tested for its effect on repression of the target roRNAs in a cell.

Palindromic Sequences In a further embodiment, the ds iRNA molecule can be palindromic cTarget sequences, in which both strands are identical or functionally identical. In one embodiment, a cTarget sequence can be analyzed to identify palindxomic sequences, for example, through the use of a computer program, such as DNA Strider. In one embodiment, a method to ifentify palindromic sequences is provided in which complementary sequence to a target mRNA is first determined. This sequence can then be analyzed for the presense of a palindromic sequence that is at least fifteen, sixteen, seventeen, eighteen, nineteen, twenty, twenty- one, twenty-two, twenty-three, twenty-four, twenty-five, twenfy-sic, twenty-seven, twenty-eight, twenty-nine, thirty, thirty-one, thirty-two, thirty-three, thrirty-four, thirty-five, thirty-six, thirty-seven, thirty-eight, thirty-nine, forty, forty-one, forty-two, forty-three, forty-four, forty-five, forty-six, forty-seven, forty-eight, forty-nine, or fifty nucleotides, in particular, nineteen to thrity-two nucleotides, or twenty-one to twenty-three nucleotides in length. Ια an alternate embodiment, such sequences can he evaluated using a computer program, such as the DNA Strider software. Such, palindromic iRNA molecules essentially eliminates the effects of endogeous strand selection in iRNA processing.

Hairpin formation can be optimized la other embodiments, methods are provided to optimize the hybridization of the two cTaxget strands, or any sequences in which hybridization is desirable. Cytosine resides in putative sequences can be replaced with uracil residues, since non-Watson-Crick base pairing is possible in RNA molecules. These uracil residues can bind to either guanine or adenosine, thereby potentially increasing the degree of hybridization between the strands. In one embodiment, Droska substrates can be modified without significant alteration in RNAi targeting by using this strategy.

Clustered Inhibitory RNAs fciRNAk Radial and linear

Additionally, inhibitory RNAs can he constructed by addition of individual inhibitory RNAs into an array or cluster. A variety of structural motifs can be used. One such motif is a cluster of individual hairpin RNAs joined in tandom with or without linker sequence. Such structures can have radial symmetry in structure (see, for example, Figure 2), without having radial symmetry in sequence, i.e. radial iRNA molecules. Alternatively, duplex RNAs can be joined with a variety of spacer sequences to produce a structure that is nearly linear or curved (see, for example, Figure 3). These structures can be produced by linking a series of oligonucleotides with or without spacer sequence and then adding the complement sequence of these oligonucleotides in the reverse order, again with or without linker sequence. In addition, the various structural strategies can be combined to produce complex structures. Both radially and clustered inhibitory RNA and linear clustered inhibitory RNA structures can mediate targeted destruction of cellular RNA via small interfering RNAs.

Clustered inhibitory RNA can be manufactured so that a angle expression vector or DNA template contains torn at least 2, 3,4,5,6,7,8, 9, 10,11, 12,13,14, 15, 20,25,50, 75, or 100 siKNA molecules capable of targeting a single region on an mRNA sequence (see, for example, Figure 4(a)). Additionally, clustered inhibitory RNA can be manufactured so that a single expression vector or DNA template contains at least 2,3,4,5, 6,7, 8, 9,10,11, 12,13,14,15,20,25,50,75, or 100 siRNAs capable of targeting multiple regions on a single mRNA target sequence (see for example, figure 4(b)). Alternatively, clustered inhibitory RNA can be manufactured so that a single expression vector contains more than one siRNA molecule capable of targeting multiple regions on multiple mRNA targets (see, for example,

Figure 4(c)). Ια annfhftr embodiment, clustered inhibitory KNA can be manufactured so that a single expression vector contains from at least 2,3,4, 5,6,7,8,9,10,11,12,13,14,15, 20, 25, 50, 75, or 100 siSNA molecules capable of targeting a homologous region on multiple mRNA target sequences. B. Additonal iRNA Molecules

Antisense Oligonucleotides

In general, antisense oligonucleotides comprise one or more nucleotide sequences sufficient in identity, number and size to effect specific hybridization with a pre-selected nucleic acid sequence. Antisense oligonucleotides used in accordance with the present invention typically have sequences that are selected to be sufficiently complementary to the target nucleic acid sequences (suitably mRNA in a target cell or organism) so that the antisense oligonucleotide forms a stable hybrid with the mRNA and inhibits the translation of the mRNA sequence, preferably under physiological conditions. The antisense oligonucleotide can be 100% complementary to a portion, of the target gene sequence. The antisense oligonucleotides can also be at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% complementary to the target nucleic acid sequence.

Antisense oligonucleotides that can be used in accordance with the present invention can be synthesized and used according to procedures that are well known in the art and that will be familiar to the ordinarily skilled artisan. Representative teachings regarding the synthesis, design, selection and use of antisense oligonucleotides include without limitation, for example, U.S. Patent No. 5,789,573, U.S. Patent No. 6,197,584, and Ellington, "Current Protocols in Molecular Biology," 2nd Ed., Ausubel et al., eds., Wiley Ihterscience, New York (1992).

Ribozvmes

Nucleic acid molecules that can be used in the present invention also include ribozymes. In general, ribozymes are ENA molecules having enzymatic activities usually associated with cleavage splicing or ligation of nucleic acid sequences to which the ribozyme binds. Typical substrates for ribozymes include KNA molecules, although ribozymes can also catalyze reactions in which DNA molecules serve as substrates. Two distinct regions can be identified in a ribozyme: the binding region which gives the ribozyme its specificity through hybridization to a specific nucleic acid sequence, and a catalytic region which gives the ribozyme the activity of cleavage, Mgation or splicing,. Ribozymes which are active intracelMarly work in cis, catalyzing only a single turnover reaction, and are usually self-modified during the reaction. However, ribozymes can be engineered to act in trans, in a truly catalytic manner, with a turnover greater than one and without being self-modified Owing to the catalytic nature of the ribozyme, a single ribozyme molecule cleaves many molecules of target nucleic acids and therefore therapeutic activity is achieved in relatively lower concentrations than those required in an antisense treatment (See, for example, WO 96/23569). ’

Ribozymes that can be used in accordance with the present invention can be synthesized and used according to procedures that are well known in the art and that will be familiar to the ordinarily skilled artisan. Representative teachings regarding the synthesis, design, selection and use of ribozymes include without limitation, for example, U.S. Patent No. 4*987,071, and U.S. PatentNo. 5,877,021.

Small Interfering RNAs (siRNAl RNA interference is mediated by double stranded RNA (dsRNA) molecules that have sequence-specific homology to their “target” nucleic arid sequences (Caplen, NJ., et al., Proc. Natl. Acad. Sri. USA 98:9742-9747 (2001)). Biochemical studies in Drosophila cell-free lysates indicate that, in certain embodiments of the present invention, the mediators of RNA-dependent gene silencing are 21-25 nucleotide “small interfering” RNA duplexes (siRNAs). Accordingly, siKNA molecules are suitably used in methods of the present invention. The siRNAs are derived from the processing of dsRNA by an RNase enzyme known as Dicer (Bernstein, E-, et al., Nature 409:363-366 (2001)). siKNA duplex products are recruited into a multi-protein siKNA complex termed RISC (RNA Induced Silencing Complex). Without wishing to be bound by any particular theory, a RISC is then believed to be guided to a target nucleic acid (suitably mRNA), where the siRNA duplex interacts in a sequence-specific way to mediate cleavage in a catalytic fashion (Bernstein, E., et al., Nature 409:363-366 (2001); Boufla, A., et aL, Curr. Biol. 11:1776-1780 (2001)).

Small interfering RNAs that can be used in accordance with the present invention can he synthesized and used according to procedures that are well known in the art and that will be familiar to the ordinarily skilled artisan. Small interfering RNAs for use in trie methods of the present invention suitably comprise between about 0 to about 50 nucleotides (nt). In examples of nonlimiting embodiments, siRNAs can comprise about 5 to about 40 nt, about 5 to about 30 nt, about 10 to about 30 nt, about 15 to about 25 nt, or about 20-25 nucleotides.

Inverted Repeats

Inverted repeats comprise single stranded nucleic acid molecules that contain two regions that are at least partially complementary to each other, oriented such that one region is inverted relative to the other. This orientation allows the two complementary sequences to base pair with each other, thereby forming a hairpin structure. The two copies of the inverted repeat need not be contiguous. There can be V additional nucleotides between the hairpin forrning sequences, wherein V is any number of nucleotides. For example, n can be at least 1, 5, 10, 25, 50, or 100 nucleotide, or more, and can be any number of nucleotides falling within these discrete values. inverted repeats that can be used in accordance with the present invention can be synthesized and used according to procedures that are well known in the art and that will be familiar to the ordinarily skilled artisan. The production and use of inverted repeats for RNA interference can be found in, without liimtefion, for example, Kirby, K. et al. Proc. NatL Acad. Sci. U S A 99:16162-16167 (2002), Adehnan, Z. N. et al. J. Virol. 76:12925-12933 (2002), Yi, C. E. et al. J, Biol. Chem. 278:934-939 (2003), Yang, S. et al. Mol. CeH Biol. 21:7807-7816 (2001), Svoboda, P. et al. Biochem. Biophys. Res. Common. 287:1099-1104 (2001), and Martinek, S. and Young, M. W. Genetics 156:171-1725 (2000).

Short Hairpin RNA fshRNAl

Paddison, PJ., et aL, Genes &amp; Dev. 16:948-958 ¢2002) have used small RNA molecules folded into hairpins as a means to effect RNA interference. Such short hairpin RNA (sbRNA) molecules are also advantageously used in foe methods of the present invention. Functionally identical to foe inverted repeats described herein, the length of the stem and loop of functional sbRNAs distinguishes them from inverted repeats. In one embodiment, stem lengths can be at least fifteen, sixteen, seventeen, eighteen, nineteen, twenty, twenty- one, twenty-two, twenty-three, twenty-four, twenty-five, twenty-six, twenty-seven, twenty-eight, twenty-nine, thirty, thirty-one, thirty-two, thirty-three, tbrirty-four, thirty-five, thirty-six, thirty-seven, thirty-eight, thirty-nine, forty, forty-one, forty-two, forty-three, forty-four, forty-five, forty-six, forty-seven, forty-eight, forty-nine, or fifty nucleotides and loop size can be at least 2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18, 19,20,25, 30, 40 or 50 nucleotides. While not wishing to be bound by any particular theory, it is believed that these shKNAs resemble the dsRNA products of the Dicer RNase and, in any event, have the same capacity for inhibiting expression of a specific gene. Hairpin RNA structures can mediate targeted destruction, of cellular RNA via small interfering RNAs (see, for example, Figure 1).

Transcription of shRNAs can be initiated at a polymerase ΠΙ (pol ΠΓ) promoter and is believed to be terminated at position 2 of a 4-5-thymine transcription termination site. Upon expression, shRNAs are thought to fold into a stem-loop structure with 3' UU-overhangs. Subsequently, the ends of these shRNAs are processed, converting the shRNAs into ~21 nt siRNA-tike molecules.

Short hairpin ENAs that can be used in accordance with the present invention can be synthesized and used according to procedures that are well known in the art and that will be familiar to the ordinarily skilled artisan. The production and use of inverted repeats fox RNA interference can be found in, wi&amp;out limitation, Partdison, PJ., et al., Genes &amp; Dev. 16:948-958 (2002), Yu, J-Y., et al. Proc. Natl. Acad. Sci. USA 99:6047-6052 (2002), and Paul, C. P. et al. Nature Biotechaol. 20:505-508 (2002).

Small TemooraHv Regulated RNAs fetRNAsl

Another group of small RNAs that can he used are the small temporally regulated RNAs (stRNAs). In general, sfRNAs comprise from about 20 to about 30 nt (Banerjee and Slack, Bioessays 24:119-129 (2002)), although stRNAs of any size can also he used in accordance with the invention. Unlike siRNAs, stRNAs downregulate expression of a target mRNA after the initiation of translation without degrading the mRNA. HL Expression of the iRNA molecules A Construct Design

The present invention provides novel constructs and DNA templates to express iRNA molecules, as well as methods to make such constructs.

In one aspect of the present invention, methods are provided to produce transgenic cells and animals that express iRNA molecules at a predetermined location, as well as the cells and animals produced thereby. DNA templates, which produce iRNA molecules, that contain sequence that targets a particular location in the genome can be introduced into cells. In one embodiment, the DNA templates can be targeted such that expression of the iRNA molecule can be achieved without disrupting the endogenous gene function. In one embodiment, the DNA templates can be in the form of vectors. The vectors can he introduced into the cells directly, or linearized prior to introduction into the cell, hi another embodiment, the DNA templates can be synthesized as oligonucleotides and introduced into cells. In one embodiment, die DMA templates can. integrate into the genome of the cell via targeted integration. The targeted integration, can be via homologous recombination. The DMA templates can be inserted via homologous recombination into, for example, a housekeeping gene such that the expression of die iRNA molecule is under the control of the associated promoter of the housekeeping gene. Alternatively, the DMA templates can be inserted via homolgous recombination into a gene that is only expressed in particular cells or organs such that the expression of the iRNA molecule is under the control of the associated promoter of the cell or organ specific gene.

In other embodiments, the DNA templates used to produce the iRNA molecules can integrate into exons of the target gene, hi another embodiment, the DNA templates used to produce the iRNA molecules caa integrate into introns of the target gene, such as into a non-esssential location of an endogenous iniron. The DMA templates can be targeted such that tiie endogenous promoter of the target gene directs transcription of (he exogenous DMA template. In still further embodiments, the DNA templates used to produce the iRNA molecules can be embedded in engineered (or synthetic) introns for integration into introns or exons of target genes. The engineered introns can be derived from any endogenous intron. In one embodiment, the endogenous intron can be reduced to its ntmimal functional components. In another embodiment, restriction sites can be engineered into the synthetic intron. In one embodiment, the restriction enzyme sites allow for placement of the DNA template into the synthetic intron. In further embodiments, the synthetic introns can he inserted into endogenous exons or introns without disrupting the function of the endogenous gene. hi another embodiment, methods are provided to produce cells and animals in which interfering KNA molecules are expressed to regulate the expression of target genes. Methods according to this aspect of the invention can include, for example: identifying one or more target nucleic acid sequences in a cell; introducing DNA templates that produce iRNA molecules that bind to the target sequence and also contain flanking sequence for homologous recombination into the cell; and expressing the DNA templates in the cell under conditions such that the iRNAs bind to the target nucleic acid sequences, thereby regulating expression of one or more target genes. In one embodiment, the present invention provides methods of producing non-human transgenic animals that heritably express iRNA molecules that regulate the expression of one or more target genes. In one embodiment, the animals can be produced via somatic cell nuclear transfer. Hie somatic cell can be engineered to express the iRNA molecule by any of the techniques described herein.

Engineered f Synthetic) Jritrons

In further embodiments, the DNA templates used to produce the iRNA molecules can be embedded in engineered (or synthetic) introns for integration into introns or exons of target genes. The engineered introns can be derived from any endogenous intron. In one embodiment, the endogenous intron can be reduced to its minimal functional components. In another embodiment, restriction sites can be engineered into the synthetic intron. In one embodiment, the restriction enzyme sites allow for placement of the DNA template into the synthetic intron. In further embodiments, the synthetic introns can be inserted into endogenous exons or introns without disrupting the function of the endogenous gene.

To obtain the expression pattern, level, and timing of an endogenous gene, one can use homologous recombination to trap all regulatory elements of the endogenous gene. However for many applications, disruption of an endogenous gene would not be acceptable. To utilize this strategy within a gene that has been characterized, one can insert the siRNA(s) into a non-essential location within an endogenous intron of the target gene. Alternatively, one can assemble an exogenous intron to be inserted into an «ton of the target gene. The exogenous intron can be naturally occuring or designed (Rriegler M. Assembly of enhancers, promoters, and splice signals to control expression of transferred genes. Methods EnzymoL 1990;185:512-27; Choi T, Huang M, Gorman C, Jaenisch R. A generic intron increases gene expression m teansgenic mice. Mol Cell Biol. 1991 Junjl 1(6):3070-4,- Palmiter RD, Sandgrea EP, Avarbodc MR, Allen DD, Brinster RL. Heterologous introns can enhance expression of transgenee hi mice. Proc Natl Acad Sci U S A. 1991 Jan 15;88(2):478-82; Petitderc D, Attal J, Theron MC, Bearzotti M, Bolifrand P, Kami G, Sthmakre MG, Pointu H, Puissant C, Houdebine LM. The effect of various introns and transcription terminators on the efficiency of expression vectors in various cultured cell lines and in the mammary gland of transgenic mice. J Biotechnol. 1995 Jim 21;40(3):169-78.

Insertion of an engineered (pr synthetic) intron within an exon of an endogenous gene will allow transcription to be controlled by that gene. Additionally, once splicing has occurred, die resulting mRNA of the endogeous gene can be returned to its normal stale. The spliced intron can then be available for further processing by cellular components to produce effective inhibitory RNA.

Synthetic Iotron assembly A synthetic intron can be designed, based cm any known intron. In one embodiment, the known intron has been well characterized in the art and thus the DNA template that produces die IKNA molecule can be inserted into a site within the intron that is known to not effect the function of the intron. Briefly, restriction enzyme sites can be engineered into the intron and the DNA template can then be inserted into the intron at a location, which is non-essential for intron function. Additionally, restriction enzyme sites can be added to the sequence 5’ and 35 of the intron to allow for targeted insertion of the synthetic intron into a target exon or intron. In one particular embodiment, the synthetic intron can contain at least a restriction enzyme site at the 5’ end, an intronic splice donor site, a DNA template that can produce at least one £RNA molecule, an interne branch site, an intronic splice acceptor site and a restriction enzyme site at the 3’ end, see, for example, the schematic below:

ha other embodiments, an engineered inten can be created from any known gene, for example, a cell or tissue-specific gene. In one embodiment, if the intron is ^characterized, the following non-limiting methodology can identify an appropriate insertion point for the DNA template, which will not effect intron function. First, sequence the intron. Then, set up a reporter assay, for example* by finking the gene to a reporter gene to test for functioning of the intron. Next, engineer restriction enzyme sites into a location of the intron and then clone into tire intron the DNA template sequence. Finally, test the synthetic construct in the reporter assay to determine whether insertion of the DNA template interfered with the functioning of the gene. This process can be completed until a non-essential location of the intron is identified for insertion of the DNA template. Further, tins process can also include I sequential deletion of intronic sequence until a minimal functional intron is identified. ~R- Ππ-ning Strategies Ια embodiments of file present invention, DNA can be spliced together to form specific nucleotide sequences. In one embodiment, DNA templates are provided that contain at least a 5’ targeting aim for homologous recombination, a first nucleotide sequence, optionally, a linker sequence, a second nucleotide sequence that substantially hybridizes to the first nucleotide sequence and a 3’ targeting arm for homologous recombination. Optionally, these DNA template can also be cloned into a synthetic intron. In one embodiment, oligonucleotide sequences can be synthesized for each component of the DNA template and/or synthetic intron and cloned together using restriction enzymes. In another embodiment, each component can be engineered in an expression vendor. In one embodiment, the vector can be introduced into the cell to achieve genetic modification of ther cell. In another embodiment, the vector can be linearized and then inserted into the cell.

In other embodiments of the present invention, at least two iKNA molecules can be expressed in a cell. In one embodiment, clustered jRNA molecules are expressed in a cell. In one embodiment, to clone a series of iRNA oligonucleotides into an expression vector the following strategy can be employed. First, a vector can be obtained with two non-compatible, unique restriction sites and then the first oligonucleotide can be directionally clone into those sites. The first oligonucleotide can be designed to destroy the one of the restriction sites upon cloning and supply a functional restriction site on the opposite end. With tins strategy, cleavage sites for the two original restriction enzymes are present in file new construct and the next oligonucleotide can be cloned into those sites. The cycle can be repeated until foe desired number of oligonucleotides are cloned and foe transgene is assemble. As an example utilizing restriction sites for Bell (tgatca) and Mini (aegegt) foe following composition can be used:

Prefix stem side 1 - loop - stem side 2 suffix

GATCtecea nnnunnntiTmnnnrmnnxmnntmnTmmi. ju tgcTGATCActaetA

Bell supplied

compatible Bel I end site

In another embodiment, to assemble oligonucleotides, for example, for clustered interference RNA, foe following strategy can be followed. Linker sequences can be used to prevent unintentional structures from forming. Nm-compatihle restriction sites can be used, for example, Bel I or MIu I sites. These sites can be cloned directionally and upstream sites can be destroyed and also re-supplied to the new vector in the downstream region in preparation for the next hairpin oligonucleotide.

The DNA constructs, templates and/or vectors disclosed herein can be inserted in either an exon or an intron of an endogenous gene. In a particular embodiment, the insertion does not alter the function of the target intron or exon. The targeting strategy serves to maintain the functional integrity of the targeted gene while exploiting its endogenous regulatory capabilities to express the iRNA molecules in the cell. Gene, including intronic and exonic, function can. be assayed using functional assays to determine whether gene function has been compromised by the insertion.

Vectors

In one embodiment, from about at least 2,3,4,5,6,7,8, 9,10,11,12,13,14,15,20, 25, 50, or 100 iRNA molecules can be cloned into a vector. The vector containing the iRNA molecules can further be introduced or inserted into a prokaryotic or eukaryotic cell, preferably resulting in expression of the iRNA molecules. In one embodiment, the iRNA molecules can be operably linked to a promoter in the vector. The promoter can be an exogenous or endogenous promoter. In an alternative embodiment, the iRNA molecules are cloned into a piomoterless vector, and inserted into the genome of a eukaryotic cell, wherein the promoterless vector is under the control of a promoter and/or other regmlatory elements associated with an endogenous gene. M a particular embodiment, such promoeteriess vectors do not disrupt cell homeostasis or the functioning of the endogenous gene.

The term "vector," as used herein, refers to a nucleic acid molecule (preferably DNA) that provides a useful biological or biochemical property to an inserted nucleic acid. "Expression vectors" according to the invention include vectors that are capable of enhancing the expression of one or more iRNA molecules that have been inserted or cloned into the ' vector, upon transformation of the vector into a cell. The terms 'Vector" and "plasmid11 are used interchangeably herein. Examples of vectors include, phages, autonomously replicating sequences (ARS), centromeres, and other sequences which are able to replicate or be repEcated in vitro or in a cell, or to convey a desired nucleic acid segment to a desired location within a cell of an animal. Expression vectors useful in the present invention include chromosomal-, episomal- and virus-derived vectors, e.g., vectors derived from bacterial plasmids or bacteriophages, and vectors derived from combinations thereof, such as cosmids and phagemids. A vector can have one or more restriction endonuclease recognition sites at which the sequences can be cut in a determinable fashion without loss of an essential biological function of the vector, and into which a nucleic acid fragment can be spliced in order to bring about its replication and cloning. Vectors can further provide primer sites, e.g., for PCR, transcriptional and/or translational initiation and/or regulation sites, recombmational signals, repKcons, selectable markers, etc. Clearly, methods of inserting a desired nucleic acid fragment which do not require the use of homologous recombination, transpositions or restriction enzymes (such, as, but not limited to, UDG cloning of PCR fragments (U.S. Pat No. 5,334,575), TA Cloning® brand PCR cloning (Invitrogen Corp., Carlsbad, Calif.)) can also he applied to clone a nucleic acid into a vector to he used according to the present invention. The vector can further contain one or more selectable markers to identify cells transformed with the vector, such as the selectable markers and reporter genes described herein. In addition, the iRNA containing expression vector is assembled to include a cloning region and apoly((J)-dependent PoUH transcription terminator.

In accordance with the invention, any vector can be used to construct the iRNA containing expression vectors of the invention. In addition, vectors known in the art and those commercially available (and variants or derivatives thereof) can, in accordance with the invention, be engineered to include one or more recombination sites for use in the methods of the invention. Such vectors can be obtained from, for example, Vector Laboratories Inc., Invitrogen, Promega, Novagen, NEB, Qontech, Boehringer Mannheim, Pharmacia, Epicenter, OriGmes Technologies Inc., Stratagene, PerkmBhner, Phattmngen, and Research Genetics. General classes of vectors of particular interest include prokaryotic and/or eukaryotic cloning vectors, expression vectors, fusion vectors, two-hybrid or reverse two-hybrid vectors, shuttle vectors for use in different hosts, mutagenesis vectors, transcription vectors, vectors for receiving large inserts.

Other vectors of interest include viral origin vectors (M13 vectors, bacterial phage λ vectors, adenovirus vectors, and retrovirus vectors), high, low and adjustable copy number vectors, vectors which have compatible replicons for use in combination in a single host (pACYC184 andpBR322) and eukaryotic episomal replication vectors (pCDM8).

Vectors of interest include prokaryotic expression vectors such as pcDNA Π, pSL301, pSE280, pSE380, pSE420, pTxcHisA, B, and C, pRSET A, B, and C (Invitrogen, Corp.), pGEMBX-1, and pGEMEX-2 (Promega, Inc.), the pET vectors (Novagen, Inc.}, pTrc99A, pKK223-3, the pGBX vectors, pEZZ18, pRH2T, and pMC1871 (Pharmacia, hie.), pKK233-2 and pKK388-l (Qontech, Inc.), and pProEx-HT (Invitrogeo, Corp.) and variants and derivatives thereof. Other vectors of interest include eukaryotic expression vectors such as pFastBac, pFastBacHT, pFastBacDUAL, pSFV, and pTet-Splice (Invitrogen), pEUK-Cl, pFUR, pMAM, pMAMneo, pBIlOl, pBI121, pDR2, pCMVEBNA, and pYACneo (Ctomech), pSVK3, pSVL, pMSG, pCHllO, and pKK232-8 (Pharmacia, Inc.), p3'SS, ρΧΠ, pSG5, pFbac, pMbac, pMClnco, and pOG44 (Stratagene, Inc.), and pYES2, pAC360, pBlneBacHis A, B, and C, pVL1392, pBlueBacin, pCDM8, pcDNAl, pZeoSV, pcDNA3 pREP4, pCEP4, and pEBVHis (Invitrogen, Crap.) and variants or derivatives thereof.

Other vectors that can be used include pUC18, pUC19, pBlueScript, pSPORT, cosmids, phagemids, YAC's (yeast artificial chromosomes), BAC's (bacterial artificial chromosomes), PI (Escherichia coli phage), pQB70, pQE60, pQB9 (quagan), pBS vectors, PhageScript vectors, BlueScript vectors, pNH8A, pNH16A, pNH18A, pNH46A (Stratagene), pcDNA3 (fovitrogen), pGEX, pTrsfus, pTrc99A, pET-5, pET-9, pKK223-3, pKK233-3, pDR540, pRTT5 (Pharmacia), pSPORTl, pSPORT2, pCMVSPORT2.0 and pSV-SPORTl (Invitrogen) and variants or derivatives thereof Viral vectors can also be used, such as lentiviral vectors (see, for example, WO 03/059923; Tiscomia et al. PNAS 100:1844-1848 (2003)).

Additional vectors of interest include pTixFus, pThioHis, pLEX, pTrcHis, pTrcHis2, pRSET, pBlueBacHis2, pcDNA3.1/His, pcDNA3.1(-)/Myc-His, pSecTag, pEBVHis, pPIC9K, pPIC3.5K, pA0815, pPICZ, pPICZo, pGAPZ, pGAPZa, PBlueBac4.5, pBlueBacHis2, pMelBac, pSinRep5, pSinffis, pIND, pIND(SPl), pVgRXR, pcDNA2.1, pYES2, pZErOl.l, pZEiO-2.1, pCR-Blunt, pSE280, pSE380, pSE420, pVL1392, pVL1393, pCDM8, pcDNAl.l, pcDNAl.l/Amp, pcDNA3.1, pcDNA3.1/Zeo, pSe, SV2, pRc/CMV2, pRc/RSV, pREP4, pREP7, pKEP8, pREP9, pREP 10, pCEP4, pEBVHis, pCR3.1, pCR2.1, pCR3.1-Uni, and pCRBac from Invitrogen; λ ExCell, λ gtl 1, pTxc99A, pKK223-3, pGEX-ΙλΤ, pGEX-2T, pGEX-2TK, pGEX-4T-l, pGEX-4T-2, pGEX-4T-3, pGEX-3X, pGEX-5X-l, pGEX-5X-2, pGEX-SX-3, pEZZ18, ρΚΓΓ2Τ, pMC1871, pSVK3, pSVL, pMSG, pCHllO, pKK232-8, pSL1180, pNEO, and pUC4K from Pharmacia; pSCREBN-lb(+), pT7Bhie(R), pT7Blue-2, pCITE-4abc(+), pOCUS-2, pTAg, pET-32LIC, pET-30LIC, pBAC-2cp LIC, pBACgus-2cp LIC, pT7Blue-2 LIC, pT7Blue-2, XSCBEEN-l, XBlueSTAR, pET-3abcd, pET-7abc, pET9abcd, pETllabcd, pET12abc, pET-14b, pET-15b, pET-16b, pBT-17b-pET-17xb, pET-19b, pET-20b(+), pET~21abcd(+), pET-22b(+), pET-23abcd(+), pET-24abcd(+), pET-25b(+), pET-26b(+), pET-27b(+), pET-28abc(+), pET-29abc(+), pET-30abc(+), PET-31b(+), pET-32abc(+), pET-33b(+), pBAC-1, pBACgus-1, pBAC4x-l, pBACgus4x-l, pBAC-3cp, pBACgus-2cp, pBACsurf-1, pig, Signal pig, pYX, Selecta Vecta-Neo, Selecta Vecta-Hyg, and Selecta Vecta-Gpt from Novagen; pLexA, pB42AD, pGBT9, pAS2-l, pGAD424, pACT2, pGAD GL, pGAD GH, pGADIO, pGilda, pEZM3, pBGFP, pEGFP-1, pEGEP-N, pEGFP-C, pEBFP, pGFPuv, pGFP, p6xHis-GFP, pSEAP2-Basic, pSEAP2-Contral, pSEAP2-Promoter, pSEAP2-Enhancer, pPgal-Basic, pjlgal-Control, pPgal-Promoter, ppgal-Bnhancer, pCMV, pTet-Off, pTet-Gn, pTK-Hyg, pRetro-OfE, pRetro-On, pIRESlneo, pIRESlhyg, pLXSN, pLNCX, pLAPSN, pMAMneo, pMAMneo-CAT, pMAMneo-LUC, pPXJR, pSV2neo, pYEX4T-l/2/3, pYBX-Sl, pBacPAK-His, pBacPAK8/9, pAcUW31, BacPAK.6, pTriplEx, XgtlO, Igtll, pWE15, and TriplEx from Clontech; Lambda ZAP H, pBK-OMV, pBK-RSV, pBluescript H KS +/-,1 pBluescript H SK +/-, pAD-GAL4, pBD-GAL4 Cam, pSurfscript, Lambda FIX H, Lambda DASH, Lambda EMBL3, Lambda BMBL4, SuperCos, pCR-Scrigi Amp, pCR-Script Cam, pCR-Script Direct, pBS +/-, pBC KS +/-, pBC SK +/-, Phagescri.pt, pCAL-n-EK, pCAL-n, pCAL-c, pCAL-kc, pET-3 abed, pET-llabcd, pSPUIK, pESP-1, pCMVLad, pOPRSVI/MCS, pOPB ΟΑΤ,ρΧΊΊ, pSG5, pPbac, pMbac, pMClneo, pMClneo Poly A pOG44, pOG45, pFRTpGAL, pNEOpGAL, pRS403, pRS404, pRS405, pRS406, pRS413, pRS414, pRS415, and pRS416 from Stratagene.

Two-hybrid and reverse two-hybrid vectors of interest include pPC86, pDBLeu, pDBTip, pPC97, p2.5, pGADl-3, pGADIO, pACt, pACT2, pGADGL, pGADGH, pAS2-l, pGAD424, pGBT8, pGBT9, pGAD-GAL4, pLexA, pBD-GAL4, pHISi, pHISi-1, placZi, pB42AD, pDG202, pJK202, pJG4-5, plSDLexA, pYESTip and variants or derivatives thereof. f D Vectors under the control of a promoter

Transcriptional control signals in eukaryotes comprise “promoter” and “enhancer” elements. Promoters and enhancers consist of short arrays of DNA sequences that interact specifically with cellular proteins involved in transcription (Maniatis et al., Science 236:1237 [1987]). Promoter and enhancer dements have been isolated from a variety of eukaryotic sources including genes in yeast, insect and mammalian cells, and viruses (analogous control elements, i.e., promoters, are also found in prokaryotes). The selection of a particular promoter and enhancer depends on what cell type is to be used to express the protein of interest Some eukaryotic promoters and enhancers have a broad host range while others are functional in a limited subset of cell types (for review see, Voss et al, Trends Biochem. Sci., 11:287 [1986]; and Maniatis et al., supra). For example, the SV40 early gene enhancer is very active in a wide variety of cell types from -many mammalian species and has been widely used for the expression of proteins in mammalian cells (Dijkema et al., EMBO J. 4:761 [1985]). Two other examples of promoter/enhancer elements active in a broad range of mammalian cell types are those from the human elongation factor la gene (Uetsukt et al., J.

Biol. Chem., 264:5791 [1989]; Kim et al., Gene 91:217 [1990]; and Mizushdma and Nagata, Nuc. Acids. Res., 18:5322 [1990]) and the long terminal repeats of the Rons sarcoma virus (Gcaman et al., Proc. NatL Acad. Sci. USA 79:6777 [1982]) and the human cytomegalovirus (Boshart et al., Cell 41:521 [1985]).

As used herein, the team ‘“promoter” denotes a segment of DNA which contains sequences capable of providing promoter functions (i.e., the functions provided by a promoter element). For example, the long terminal repeats of retroviruses contain promoter functions. The promoter may be “endogenous” or “exogenous” or “heterologous.” An “endogenous” promoter is one which is associated with a given gene in the genome. An “exogenous” or ‘heterologous” promoter is one which is placed in juxtaposition to a gene by means of genetic manipulation (i.e., molecular biological techniques such as cloning and recombination) such that transcription of that gene is directed by the linked promoter. Promoters can also contain enhancer activities. a. Endogenous promoters

In one embodiment, the operably linked promoter of the £RNA molecule containing vector is an endogenous promoter. In one aspect of this embodiment, the endogenous promoter can be any unregulated promoter that allows for the continual transcription of its associated gene.

In another aspect, toe promoter can be a constitutive!/ active promoter. More preferably, toe endogenous promoter is associated with a housekeeping gene. Non limiting examples of housekeeping genes whose promoter can be operably linked to toe iKNA include the conserved cross species analogs of the following human housekeeping genes; mitochondrial 16S fRNA, ribosomal protein L29 (RPL29), H3 histone, family 3B (H3.3B) (H3F3B), poly(A)-bincBng protein, cytoplasmic 1 (PABPC1), HLA-B associated transcript-1 (D6S81E), surfeit I (SURF1), ribosomal protein L8 (RPL8), ribosomal protein L38 (RPL38), catechol-O-metoyltransferase (COMT), ribosomal protein S7 (RPS7), heat shock 27kD protein 1 (HSPB1), eukaryotic translation elongation factor 1 delta (guanine nucleotide exchange protein.) (EEF1D), vimentin (VTM), ribosomal protein L41 (RPL41), carboxylesterase 2 (intestine, liver) (CES2), exportin 1 (CRM1, yeast, homolog) (XPOl), uMquinol-cytochrome c reductase hinge protein (UQCRH), Glutathione peroxidase 1 (GPX1), ribophorin Π (RPN2), Pleckstrin and Sec7 domain protein (PSD), human cardiac troponin T, proteasome (prosome, macropain) subunit, beta type, 5 (PSMB5), cofilin 1 (nonmuscle) (CFL1), seryl-tRNA synthetase (SARS), catenin (cadherin-associated protein), beta 1 (88kD) (CTNNB1), Daffy blood group (FY), erythrocyte membrane protein band 7.2 (stamatin) (EPB72), Fas/Apo-1, LIM and SIB protein 1 (LASPI), accessory proteins BAP31/BAP29 (DXS1357E), nascent-polypqptide-associated complex alpha polypeptide (NACA), ribosomal protein LI 8a (RPL18A), TOT recqptor-associated factor 4 (TRAF4), MLN51 protein (MLN51), ribosomal protein Lll (RPL11), Poly(rC)-birLdmg protein 2 (PCBP2), thioxedoxin (TXN), giutarninyl-tRNA synthetase (QARS), testis enhanced gene transcript (TEGT), prostatic binding protein (PBP), signal sequence receptor, beta (translocon-associated protein, beta) (SSR2), ribosomal protein L3 (RPL3), cenfrin, EF-hand protein^ (CETN2), heterogeneous nuclear ribonucleoprotein K {HNRPK), glutathione peroxidase 4 (phospholipid hydroperoxidase) (GPX4), fusion, derived from t(12;16) malignant lipo sarcoma (FUS), ATP synthase, H+ transporting, mitochondrial FO complex, subunit c (subunit 9), isofonn 2 (ATP5G2), ribosomal protein S26 (RPS26), ribosomal protein L6 (RPL6), ribosomal protein SI 8 (RPS18), serine (or cysteine) proteinase inhibitor, clade A (alpha-1 antiproteinase, antitrypsin), member 3 (SERPINA3), dual specificity phosphatase 1 (DUSP1), peroxiredoxin 1 (PRDX1), epididymal secretory protein (l9.5kD) (HE1), ribosomal protein S8 (RPS8), translocated promoter region (to activated MET oncogene) (TPR), ribosomal protein L13 (RPL13), SON DNA binding protein (SON), ribosomal prot LI 9 (RPL19), ribosomal prot (homolog to yeast S24), CD63 antigen (melanoma 1 antigen) (CD63), protein lyrosine phosphatase, non-receptor type 6 (PTPN6), eukaryotic translation elongation factor 1 beta 2 (EEF1B2), ATP synthase, H+ transporting, mitochondrial FO complex, subunit b, isoform 1 (ATP5FI), solute carrier family 25 (mitochondrial carrier, phosphate carrier), member 3 (SLC25A3), tryptophanyl-tRNA synthetase (WARS), glutamate-ammonia ligase (glutamine synthase) (GLUL), ribosomal protein L7 (RFL7), interferon induced transmembrane protein 2 (1-8D) (IFnM2), tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, beta polypeptide (YWHAB), Casein kinase 2, beta polypeptide (CSNK2B), ubiquitin A-52 residue ribosomal protein fusion product 1 (UBA52), ribosomal protein L13a (RPL13A), major histocompatibility complex, class I, E (HLA-E), jun D proto-oncogene (JUND), tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, tiieta polypeptide (YWHAQ), ribosomal protein L23 (RPL23), Ribosomal protein S3 (RPS3 ), ribosomal protein L17 (RPL17), filamin A, alpha (actin-binding protein-280) (PLNA), matrix Gla protein (MGP), ribosomal protein L35a (RPL35A), peptidylprolyl isomerase A (cyclophilin A) (PP1A), villin 2 (ezrin) (VII2), eukaryotic translation elongation factor 2 (EEF2), jun B proto-oncogene (JUNB), ribosomal protein S2 (RPS2), cytochrome c oxidase subunit Vile (COX7C), heterogeneous nuclear riboimcleoproteixi L (HNEJPL), tumor protein, translationally-conlrolled 1 (ΤΡΤΊ), ribosomal protein L31 (RPL31), cytochrome c oxidase subunit YUa polypeptide 2 (liver) (COX7A2), DEAD/H (Asp-Glu-Ala-Asp/His) box polypeptide 5 (RNA helicase, 68kD) (DDX5), cytochrome c oxidase subunit Via polypeptide 1 (COX6A1), heat shock 90kD protein 1, alpha (HSPCA), Sjogren syndrome antigen B (autoantigen La) (SSB), lactate dehydrogenase B (LDHB), high-mobility group (nonhistone chromosomal) protean 17 (HMG17), cytochrome c oxidase subunit Vic (COX6C), heterogeneous nuclear rfbomicleoprotera A1 (HNRPA1), aldolase A, fructo se-bisphosphate (ALDOA), integrin, beta 1 (fibronectin receptor, beta polypeptide, antigen CD29 includes MDF2, MSK12) (TTGB1), ribosomal protein Sll (RPSll), small nuclear ribonucleoprotein 70kD polypeptide (RN antigen) (SNRP20), guanine nucleotide binding protein (G protein), beta polypeptide 1 (GNB1), heterogeneous nuclear ribonucleoprotein A1 (KNRPA1), calpain 4, small subunit (30K) (CAPN4), elongation factor TU (N-teiminus)/X03689, ribosomal protean L32 (RPL32), major histocompatibility complex, class H, DP alpha 1 (HLA-DPA1), superoxide dismutase 1, soluble (amyotrophic lateral sclerosis 1 (adult)) (SOD1), lactate dehydrogenase A (LDHA), glyceraldehyde-3-phosphate dehydrogenase (GAPD), Actin, beta (ACTB), major histocompatibility complex, class Π, DP alpha (HLA-DRA), tubulin, beta polypeptide (TUBB), metallothionein 2A (MT2A), phosphoglycerate kinase 1 (PGK1), KRAB-associated protein 1 (TIF1B), eukaryotic translation initiation factor 3, subunit 5 (epsilon, 47kD) (BIF3S5), NADH dehydrogenase (ubiquinone) 1 alpha subcomplex, 4 (9kD, MLRQ) (NDUFA4), chloride intracellular charnel 1 (CLIC1), adaptor-related protein complex 3, sigma 1 subunit (AP3S1), cytochrome c oxidase subunit IV (COX4), PDZ and UM domain 1 (elfin) (PDLIM1), glutathione-S-transferase like; glutathione transferase omega (GSTTLp28), interferon stimulated gene (20kD) (ISG20), nuclear factor I/B (NF1B), COXIO (yeast) homolog, cytochrome c oxidase assembly protein (heme A: famesyltransferase), conserved gene amplified in osteosarcoma (OS4), deoxyhypusine synthase (DHPS), galactosidase, alpha (GLA), microsomal glutathione S-transferase 2 (MGST2), eukaryotic translation initiation factor 4 gamma, 2 (EIF4G2), ubiquitin carrier protein E2-C (UBCH10), BTG family, member 2 (BTG2), B-cell associated protein (REA), COP9 subunit 6 (MOV34 homolog, 34 kD) (MOV34-34KD), ATX1 (antioxidant protein 1, yeast) homolog 1 (ATOX1), acidic protein rich in leucines (SSP29), poly(A)-bmding prot (PABP) promoter region, selenoprotein W, 1 (SEPW1), eukaryotic translation initiation factor 3, subunit 6 (48kD) (EIF3S6), carnitine palmitoyltransferase I, muscle (CPT1B), transmembrane trafficking protein (ΊΜΡ21), four and a half LIM domains 1 (FHL1), ribosomal protein S28 (EPS28), myeloid leukemia factor 2 (MLF2), neurofilament triplet L prot/U57341, capping protein (actin filament) muscle Z-Hne, alpha 1 (CAJPZA1), 1-acyl$ycerol-3-phosphate O-acyltransferas e 1 (lysophosphatidic acid acyltransferase, alpha) (AGPAT1), inositol 1,3,4-triphosphate 5/6 kinase (CIPK1), histidine triad nucleotide-binding protein (HINT), dynamitic (dynactin complex 50 iD subunit) (DCIN-50), actin related protein 2/3 complex, subunit 2 (34 fcD) (ARPC2), histone deacetylase 1 (HDAC1), ubiquitin B, chitbase 3-like 2 (CHI3L2), D-dopachrome tautomerase (DDT), zinc finger protein 220 (ZNF220), sequestosome 1 (SQSTM1), cystatin B (stefin B) (CSTB), eukaryotic translation initiation factor 3, subunit 8 (llOkD) (BIF3S8), chemokine (C-C motif) receptor 9 (CCR9), ubiquitin specific protease 11 (USP11), laminin receptor 1 (67kD, ribosomal protein SA) (LAMR1), anrplified in osteosarcoma (OS-9), splicing factor 3b, subunit 2, !45kD (SF3B2), integrin-linked kinase (ILK), ubiquitin-conjugafing enzyme E2D 3 (homologous to yeast UBC4/5) (UBE2D3), chaperonin containing TCP1, subunit 4 (delta) (CCT4), polymerase (SNA) Π (DNA directed) polypeptide L (7.6kD) (POLR2L), nuclear receptor co-repressor 2 (NCOR2), accessory proteins BAP31/BAP29 (DXS1357E, SLC6A8), 13kD differentiation-associated protein (LOC55967), Taxi (human T-cell leukemia virus type I) binding protean 1 (TAX1BP1), damage-specific DNA binding protein. 1 (127kD) (DDB1), dynenx, cytoplasmic, light polypeptide (PIN), methionine aminopeptidase; eD?-2-associated p67 (MNPEP), G protein pathway suppressor 2 (GPS2), ribosomal protein L21 (RPL21), coatomer protein complex, subunit alpha (COPA), G protein pathway suppressor 1 (GPS1), small nuclear ribonucleoprotein D2 polypeptide (16.5kD) (SNRPD2), ribosomal protein S29 (RPS29), ribosomal protein S10 (RPS10), ribosomal proteinS9 (RPS9), ribosomal protein S5 (RPS5), ribosomal protein L28 (RPL28), ribosomal protein L27a (RPL27A), protein tyrosine phosphatase type IVA, member 2 (PTP4A2), ribosomal prot L36 (RPL35), ribosomal protein LlOa (RPL10A), Fc fragment of IgG, receptor, transporter, alpha (FCGRT), maternal G10 transcript (G10), ribosomal protein L9 (RPL9), ATP synthase, H+ transporting, mitochondrial F0 complex, subunit c (subunit 9) isoform 3 (ATP5G3), signal recognition particle 14kD (homologous Alu KNA-hinding protein) (SEP14), mutL (E. coli) homolog 1 (colon cancer, nonpolyposis type 2) (MLH1), chromosome Iq subtelomeric sequence D1S553./U06155, fibrofflodulin (FMOD), amino-terminal enhancer of split (AES), Eho GTPase activating protein 1 (ARHGAP1), non-POU-domain-containing, octamex-binding (ΝΟΝΟ), v-taf murine sarcoma 3611 viral oncogene homolog 1 (ARAF1), heterogeneous unclear ribonucleoprotein Al (HNRPA1), beta 2-microglobu3in (B2M), ribosomal protein S27a (RPS27A), bromodommn-containing 2 (BRD2), azoospermia factor 1 (AZF1), upregulated by 1,25 dihydroxyvitainm. D-3 (VDUPl), serine (ox cysteine) proteinase inhibitor, clade B (ovalbumin), member 6 (SKRPINB6), destrin (actin depolymerizing factor) (ADF), thymosin beta-10 (IMSB10), CD34 antigen (CD34), spectrin, beta, rum-erythrocytic 1 (SPTBN1), angio-associaied, migratory cell protein (AAMP), major histocompatibility complex, class I, A (BDLA-A), MYC-associated zinc finger protean (purine-binding transcription factor) (MAZ), SET translocation (myeloid leukemia-associated) (SET), paired box gene(aniridia, keratitis) (PAX6), zinc finger protein homologous to Zfp-36 in mouse (ZFP36), FK506-binding protein 4 (59kD) (FKBP4), nucleosome assembly protein 1-like 1 (NAP1L1), tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, zeta polypeptide (YWHAZ), ribosomal protein S3A (RPS3A), ADP-ribosylation factor 1, ribosomal protein S19 (RPS19), transcription elongation factor A (SB), 1 (TCBA1), ribosomal protein S6 (RPS6), ADP-ribosylation factor 3 (ARF3), moesin (MSN), nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (NFKBIA), complement component 1, q subcomponent binding proteia (C1QBP), ribosomal protein S25 (RPS25), dusterin (complement lysis inhibitor, SP-40,40, sulfated glycoprotein 2, testosterone-repressed prostate message 2, apolipopxotein J) (CLU), nucleolin (NCL), ribosomal protein S16 (RPS16), ubiquitixL-activating enzyme El (A1S9T and BN75 temperature sensitivity complementing) (ΌΒΕ1), lectin, galactoside-hinding, soluble, 3 (galectin 3) (LGALS3), eukaryotic translation elongation factor 1 gamma (EBF1G), pim-1 oncogene (PIM1), S100 calcium-binding protein AID (annexin H ligand,calpactin I, light polypeptide (pll)) (S100A10), H2A histone family, member Z (H2AFZ), ADP-ribosylation factor 4 (ARF4) (ARE4), ribosomal protein L7a (RPL7A), major histocompatibility complex, class Π, DQ alpha 1 (HLA-DQA1), PBC506-binding protein 1A (12kD) (FKBP1A), CD81 antigen (target of antiproliferative antibody 1) (CD81), ribosomal protein S15 (RPS15), X-box binding protein 1 (XBP1), major histoconpatMity complex, class Π, DN alpha (HLA-DNA), ribosomal protein S24 (RPS24), leukemia-associated phosphoprotein pl8 (statimrin) (LAP18), myosin, heavy polypeptide 9, non-muscle (MYH9), casein kinase 2, beta polypeptide (CSNK2B), fucosidase, alpha-L- 1, tissue (FUCA1), diaphoxase (NADH) (cytochrome b-5 reductase) (DIA.1), cystatin C (amyloid angiopathy and cerebral hemorrhage) (CST3), ubiquitin C (UBC), ubiquinol-cytochrome c reductase binding protein (UQCRB), prothymosin, alpha (gene sequence 28) (PTMA), glutathione S-transferase pi (GSTP1), guanine nucleotide binding protein (G protein), beta polypeptide 2-like 1 (GNB2L1), nucleophosmin (nucleolar phosphoprotein B23, numatrin) (NPM1), CD3E antigen, epsilon polypeptide (TiT3 complex) (CD3E), calpain 2, (m/Π) large subunit

(CAPN2), NADH dehydrogenase (udqumonc) flavoprotem 2 (24kD) (NDUFV2), heat shock 60kD pcrotein 1 (chapexonin) (HSPD1), guanine nucleotide binding protein (G protein), alpha stimulating activity polypeptide 1 (GNAS1), clatbrin, light polypeptide (Lea) (CLTA), ATP synthase, H+ transporting, mitochondrial FI complex, beta polypeptide, calmodulin 2 (phosphorylase kinase, delta) (CALM2), aefin, gamma 1 (ACTG1), ribosomal protein S17 CRPS17}, ribosomal protein, large, PI (RPLP1), ribosomal protein, large, PO (RPLPO), thymosin, beta 4, X chromosome (TMSB4X), heterogeneous nuclear ribonucleoprotein C (C1/C2) (HNRPC), ribosomal protein L36a (RPL36A), glucuronidase, beta (GUSB), FYN oncogene related to SRC, FGR, YES (FYN), prothymosin, alpha (gene sequence 28) (PTMA), enolase 1, (alpha) (ΕΝΌ1), laminin receptor 1 (67kD, ribosomal protein SA) (LAMR1), ribosomal protein S14 (RPS14), CD74 antigen (invariant polypeptide of major histocompatibility complex, class Π antigen-associated), esterase D/formjdglutatfaione hydrolase (BSP), H3 histone, family 3A (H3F3A), ferritin, light polypeptide (FTL), Scc23 (S. cerevisiae) homolog A (SEZ23A), actin, beta (ACTS), presenilin 1 (Alzheimer disease 3) (PSEN1), interleukin-1 receptor-associated kinase 1 (IRAKI), zinc finger protein 162 (ZNF162), ribosomal protein L34 (RPL34), beclin 1 (coiled-coil, myosin-like BCL2-interacting protein) (BECN1), phosphatidylinositol 4-kinase, catalytic,· alpha polypeptide (PK4GA), IQ motif containing GTPase activating protein 1 (IQGAP1), signal transducer and activator of transcription 3 (acute-phase response factor) (STAT3), heterogeneous nuclear ribonucleoprotein F (HNRPF), putative translation initiation factor (SUIl), protein translocation complex beta (SEC61B), xas homolog gene family, member A (ARHA), ferritin, heavy polypeptide 1 (FIH1), Kho GDP dissociation inhibitor (GDI) beta (ARHGDIB), H2A histone family, member 0 (H2AF0), annexin A11 (ANXA11), ribosomal protein 127 (RPL27), adenylyl cyclase-associated protein (CAP), zinc finger protein 91 (HPF7, HTF10) (ZNF91), ribosomal protein LI 8 (RPL18), famesyltransferase, CAAX box, alpha (FNTA), sodium channel, voltage-gated, type 3, beta polypeptide (SCN1B), calnexin (CANX), proteolipid protein 2 (cdonic epitoehum-enriched) (PLP2), amyloid beta (A4) precursor-like proton 2 (APLP2), Voltage-dependent anion channel 2, proteasome (prosome, macropain) activator subunit 1 (PA28 alpha) (PSME1), ribosomal prot L12 (RPL12), ribosomal protein L37a (RPL37A), ribosomal protein S21 (RPS21), proteasome (prosome, macropain) 26S subunit, ATPase, 1 (PSMC1), major histocompatibility complex, class Π, DQ beta 1 (HLA-DQB1), replication protein A2 (32kD) (RPA2), heat shock 90kD protein 1, beta (HSPCB), cytochrome c oxydase subunit VUE (COX8), eukaryotic translation elongation factor 1 alpha 1 (EBF1A1), SNRPN upstream reading frame (SNURF), lectin, galactoside-binding, soluble, 1 (galcctin 1) (LGALS1), lysosomal-associated membrane protein 1 (LAMP1), phosphoglycerate mutase 1 (brain) (PGAM1), interferon-induced transmembrane protein 1 (9-27) QGFITM1), nuclease sensitive element binding protein 1 (NSBP1), solute carrier family 25 (mitochondrial carrier; adenine nucleotide translocator), member 6 (SLC25A5), ADP-ribosyltransferase (NAD+; poly (ADP-ribose) polymerase) (ADPRT), leukotriene A4 hydrolase (LTA4H), profiHn 1 (PFN1), prosaposin (variant Gaucher disease and variant metachromatic leukodystrophy) (PSAP), solute carrier family 25 (mitochondrial carrier; adenine nucleotide translocator), member 5 (SLC25A5), beta-2 microglo'bulro, insulin-like growth factor binding protein 7, Ribosomal prot S13, Epstein-Barr Virus Small Rna-Associated prot, Major Histocompatibility Complex, Class I, C X58536), Ribosomal prot S12, Ribosomal prot L10, Transformation-Related prot, Ribosomal prot L5, Transcriptional Coactivator Pc4, Cathepsin B, Ribosomal prot L26, "Major Histocompatibility Complex, Class IX12432", Wihn S Tumor-Related prot, Tropomyosin Tm30nm Cytoskeletal, liposomal Protein S4, X-Linked, Ribosomal prot 137, Metahopanstimulin 1, Ribosomal prot 130, Heterogeneous Nuclear Ribonucleoprot K, Major Histocompatibility Complex, Class I, E M21533, Major Histocompatibility Complex, Class I, E M20022, Ribosomal protein L30 Homolog Heat Shock prot 70 Kda, "Myosin, Light Cham/U02629", "Myosin, Light Chain/U02629’', Calcyclin, Single-Stranded Dna-Binding prot Mssp-1, Trio3ephosphate Isomerase, Nuclear Mitotic Apparatus prot 1, prot Kinase Ht31 Camp-Dependent, Tubulin, Beta 2, Calmodulin Type I, Ribosomal prot S20, Transcription Factor Btf3b, Globin, Beta, Small Nuclear RibonucleoprotednPolypeptide CAlt. Splice 2, Nucleoside Diphosphate Kinase Nm23-H2s, Ras-Related C3 Botulinum Toxin Substrate, activating transcription factor 4 (tax-responsive enhancer element B67) (ATF4), prefoldin (PFDN5), N-myc downstream regulated (NDRG1), ribosomal protein L14 (RPL14), nicastrin (KIAA0253), protease, serine, 11 (IGF binding) (PRSS11), KIAA0220 protein (KIAA0220), dishevelled 3 (homologous to Drosophila dsh) (DVL3), enhancer of rudimentary Drosophila homolog (BRH), RNA-binding protein gene with multiple splicing (RBPMS), 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase (ATIC), KIAA0164 gene product (ΚΪΑΑ0164), ribosomal protein L39 (RPL39), tyrosine 3 monooxygenase/tcyptophan 5-monooxygenase activation protein, eta polypeptide (YWHAH), Ornithine decarboxylase antizyme 1 (OAZ1), proteasome (prosome, macropain) 26S subunit, non-ATPase, 2 (PSMD2), cold inducible RNA-binding protein (CIRBP), neural precursor cell expressed, developmentally down-regulated 5 (NEDD5), high-mobility group nonhistone chromosomal protein 1 (HMG1), malate dehydrogenase 1, NAD (soluble) (MDH1), cyclin I (CCNT), proteasome (prosome, macropam) 26S subunit, non-ATPase, 7 (Mov34 homolog) (PSMD7), major histocompatibility complex, class I, B (EDLA-B), ATPase, vacuolar, 14 kD (ATP6S14), transcription fector-Hke 1 (TGFL1), KIAA0084 protein (KIAA0084), proteasome (prosome, macropain) 26S subunit, non-ATPase, 8 (PSMD8), major histocompatibility complex, class I, A (HIA-A), alanyl-tRNA synthetase (AARS), lysyl-tRNA synthetase (KARS), ADP-ribosylation factor-like 6 interacting protein (ARL6IP), KIAA0063 gene product (KIAA0063), actin binding LIM protein 1 (ABLXM), DAZ associated protein 2 (DAZAP2), eukaryotic translation initiation factor 4A, isoform 2 (EIF4A2), CD151 antigen (CD151), proteasome (prosome, macropain) subunit, beta type, 6 (PSMB6), proteasome (prosome, macropain) subunit, beta type, 4 (PSMB4), proteasome (prosome, macropain) subunit, beta type, 2 (PSMB2), proteasome (prosome, macropain) subunit, beta type, 3 (PSMB3), WiHiams-Beuren syndrome chromosome region 1 (WBSCR1), ancient ubiquitous protein 1 (AUP1), KIAA0864 protein (KIAA0864), neural precursor cell expressed, developxnentally down-regulated 8 (NEDD8), ribosomal protein L4 (KPL4), KIAA0111 gene product (KIAA0111), transgeHn 2 (TAGLN2), Clathrin, heavy polypeptide (He) (CLTC, CLTCL2), ATP synthase, H+ transporting, mitochondrial Flcomplex, gamma polypeptide 1 (ATP5C1), calpastatin (CAST), MORF-related gene X (KIA0026), ATP synthase, H+ transporting, mitochondrial FI complex, alpha subunit, isoform 1, cardiac muscle (ATP5A1), phosphatidyiserine synthase 1 (PTDSS1), anti-oxidant protein 2 (non-selenium glutathione peroxidase, acidic calcium-independent phospholipase A2) (KIAA0106), KIAA0102 gene product (KIAA0102), ribosomal protein S23 (RPS23), CD164 antigen, sialomucin (CD 164), GDP dissociation inhibitor 2 (GDI2), enoyl Coenzyme A hydratase, short chain, 1, mitochondrial (ECHS1), eukaryotic translation initiation factor 4A, isoform 1 (EIF4A1), cyclin D2 (CCND2), heterogeneous nuclear ribonucleqprotem U (scaffold attachment factor A) (HKRPU), APEX nuclease (multifunctional DNA repair enzyme) (APEX), ATP synthase, H+ transporting, mitochondrial FO complex, subunit c (subunit 9), isoform 1 (ATP5G1), myristoylated alanine-rich protein kinase C substrate (MARCKS, 80K.-L) (MACS), annexin A2 (ANXA2), similar to S. cerevisiae RER1 (RER1), hyaluronoglucosamimdase 2 (HYAL2), uroplakm 1A (UPK1A), nuclear pore complex interacting protein. (NPIP), karyopherin alpha 4 (importin alpha 3) (KPNA4), ant the gene with multiple splice variants near HD locus on4pl6.3 (RES4-22).

In addition, the endogenous promoter can be a promoter associated with die expression of tissue specific or physiologically specific genes, such as heat shock genes. In this way, expression of the iRNA molecules can be tightly regulated. b. Exogenous promoters

In another embodiment, die promoter can be an exogencms promoter, such as a ubiquitously expressed promoeter, such a RNa polymerase promoeters, such as HI or U6; or constitutively active viral promoter. Non-limiting examples of promoters include the RSV LTR, the SV40 early promoter, the CMV IE promoter, the adenovirus major late promoter, Sra-promoter (a -very strong hybrid promoter composed of the SV40 early promoter fused to the R/U5 sequences from the HTLV-I LTR), and the Hepatitis B promoter. B- Confirmation of Target Susceptibility

Based on. sequence conservation, primers are designed and used to amplify coding regions of the target genes. Initially, the most highly expressed coding region from each gene is used to build a model control gene, although any coding or non coding region can be used Each control gene is assembled by inserting each coding region between a reporter coding region and its poly(A) signal. These plasmids produce an mSNA with a reporter gene in the upstream portion of the gene and a potential iRNA target in the 3’ non-coding region. The effectiveness of individual iRNAs is assayed by suppression of the reporter gene. Reporter genes useful in the methods of the present invention include acetohydroxyadd synthase (AHAS), alkaline phosphatase (AP), beta galactosidase (LacZ), beta glucoromdase (GUS), chloramphenicol acetyltransferase (CAT), green fluorescent protein (GFP), red fluorescent protein (REP), yellow fluorescent protean (YEP)» cyan fluorescent protein (CEP), horseradish peroxidase (HEP), luciferase (Luc), nopaline synthase (NOS), octopine synthase (OCS), and derivatives thereof. Multiple selectable markers are available that confer resistance to ampicillin, bleomycin, chloramphenicol, gentamycin, hygromycin, kanamycin, lincomycm, methotrexate, phosphinotbridn, pnromycin, and tetracycline. Methods to determine suppression of a reporter gene are well known in the ait, and include, but are not limited to, fluorometric methods (e.g. fluorescence spectroscopy, Fluorescence Activated Cell Sorting (FACS), fluorescence microscopy), antibiotic resistance determination.

Although biogenomic information and model genes are invaluable for high-throughput screening of potential iRNAs, interference activity against target nucleic adds ultimately must be established experimentally in cells which express the target nucleic add.

To determine the interference capability of the iRNA sequence, the iRNA containing vector is transfected into appropriate cell lines which express that target nucldc acid. Each selected iRNA construct is tested for its ability to reduce steady-state mRNA of the target nucleic acid la addition, any target mKNAs that "survive” the first round of testing are amplified by reverse transcriptase-PCR and sequenced (see, for example, Sambrook, J. et al. "Molecular Goning; A Laboratory Manual", 2nd addition, Cold Spring Harbor Laboratory Press, Plaioview, New York (1989)). These sequences are analyzed to determine individual polymorphisms that allow mRNA to escape the current library of iRNAs. This information, is used to further modify iRNA constructs to also target rarer polymorphisms.

Methods by which to transfect cells with iRNA vectors are well known in the art and include, but are not limited to, electroporation, particle bombardment, microinjection, transfection with viral vectors, transfection with retrovirus-based vectors, and liposome-mediated transfection, C. Expression Patterns

Transient expression of iRNA la one embodiment of tire present invention, expression of the iRNA in a cell is transient, Transient expression can be from an expression vector that does not insert into the genome of the cell. Alternatively, transient expression can be from fee direct insertion of iRNA molecules into fee cell.

Any of the types of nucleic adds that mediate RNA interference can be synthesized in vitro using a variety of methods well known in the art and inserted directly into a cell. In addition, dsRNA and other molecules that mediate RNA interference axe available from commercial vendors, such as Ribophairna AG (Kubnacb, Germany), Eurogentec (Seraing, Belgium), Sequitur (Natick, MA) and Ihvitrogea (Carlsbad, CA). Eurogentec offers dsRNA that has been labeled wife fluorophores (e.g., HEX/TBT; 5’-Fluorescein, 6-FAM; V-Fluorescein, 6-FAM; Fluorescein dT internal; 5’ TAMRA, Rhodamine; 3’ TAMRA, RJhodamine), which can also be used in fee invention. iRNA molecules can be made through the well-known technique of solid-phase synthesis. Equipment for such synthesis is sold by several vendors including, for example, Applied Biosystems (Foster City, Calif,). Other methods for such synthesis that are known in fee art can additionally or altesmatively be employed. It is well-known to use similar techniques to prepare oligonucleotides such as fee phosphorothioates and alkylated derivatives. By way of non-limiting example, see, for example, U.S. Patent No. 4,517,338, and 4,458,066; Lyer RP, et al., Cuir. Opin. Mol Ther. 1:344-358 (1999); and Verma S, and Eckstein F„ Annual Rev. Biochem. 67:99-134 (1998). iRNA directly inserted into a cell can include modifications to either the phosphate-sugar backbone or the nucleoside. For example, the phosphodiester linkages of natural RNA can be modified to include at least one of a nitrogen or sulfur heteroatom. The interfering RNA can be produced enzymatically or by partial/total organic synthesis. The constructs can be synthesized by a cellular RNA polymerase or a bacteriophage RNA polymerase (e.g., T3, T7, SP6). If synthesized chemically or by in vitro enzymatic synthesis, the RNA can be purified prior to introduction into a cell or animal. For example, RNA can be purified from a mixture by extraction -with a solvent or resin, precipitation, electrophoresis, chromatography or a combination thereof as known in the art. Alternatively, the interfering RNA construct can be used without, or with a minimum of purification to avoid losses due to sample processing. The iRNA construct can be dried for storage or dissolved in an aqueous solution. The solution can contain buffers or salts to promote annealing, and/or stabilization of the duplex strands. Examples of buffers or salts that can be used in the present invention include, but are not limited to, saline, PBS, N-tl-Hydroxyetoyl^perazme-N'^-ethanesutfomc acid) (HEPES®), 3-(N-MoiphoKno)pmpaaesulfonic acid (MOPS), 2-bis(2-Hydmxyethyl€ne)arriin0-2-Oiydroxymethyl)-l ,3 -propanediol (bis-TRIS®), potassium phosphate (KP), sodium phosphate (NaP), dibasic sodium phosphate (Na2HP04), monobasic sodium phosphate (NaH2P04), monobasic sodium potassium phosphate (NaKHP04),. magnesium phosphate (Mg3(P04)2-4H20), potassium acetate (CH3COOH), D(+)-a-sodium glycerophosphate (H0CB2CH(0H)CH20P03Na2) and other physiologic buffers known to those skilled in the art. Additional buffers for use in the invention include, a salt M-X dissolved in aqueous solution, association, or dissociation products thereof where M is an alkali metal (eg., Li+, NaH~, K+, Rb+), suitably sodium or potassium, and where X is an anion selected from the group consisting of phosphate, acetate, bicarbonate, sulfate, pyruvate, and an organic monophosphate ester, glucose 6-phosphate or DL-ct-glycerol phosphate.

Stable Expresssion of iRNA 1. Random Insertion

Genomic Insertion of the iRNA containing vector can be accomplished using any known methods of the art In one embodiment, the vector is inserted into a genome randomly using a viral based' vector. Insertion of the vitally based vector occurs at random sites consistent with viral behavior (see, for example, Daley et al. (1990) Science 247:824-830; Guild et al. (1988) J Virol 62:3795-3801; Miller (1992) Curr Topics MxcroBiol Immunol 158:1-24; Samarut et al. (1995) Methods Enzymol 254:206-228). Non limiting examples of •viral based vectors include Moloney murine leukemia retrovirus, the murine stem cell virus, vaccinia viral vectors, Sindbis virus, Semffitii Forest alphavirus, EBV, ONYX-15, adenovirus, or lentivirus based vectors (see, for example, Heanann MT et al. (2003) Nature Genet 33:396-400; Paddison &amp; Harmon (2002) Cancer Cell 2:17-23; Brummelkamp TR et al. (2002) Cancer Cell 2:243-247; Stewart SA et aL (2003) KNA 9:493-501; Rubinson DA et al. (2003) Nature Genen. 33:401-406; QinXetal. (2003) PNAS USA 100:183-188; Lois C et al. (2002) Science 295:868-872).

In another embodiment, fee transgene is either cleaved from the vector or is maintained without a vector. Vector removal can be important for certain transgene configurations previously described in fee art (Kjer-Nielsen L, Hohriberg K, Perera JD, McCluskey J. Impaired expression of chimaeric major histocompatibility complex transgenes .associated wife plasmid sequences. Transgenic Res. 1992 M; 1(4) :182-7.) The “vectorless" transgene is inserted into a genome randomly using any known method of fee art. 2. Targeted insertion

In another embodiment, the insertion is targeted to a specific gene locus through homologous recombination. Homologous recombination provides a precise mechanism fox targeting defined modifications to genomes in living cells (see, for example, Vasquez KM et al. (2001) PNAS USA 98(15):8403-8410). A primary step in homologous recombination is DNA strand exchange, which involves a pairing of a DNA duplex with at least one DNA strand containing a complementary sequence to form an intermediate recombination structure containing heteroduplex DNA (see, for example, Radding, C. M. (1982) Aim. Rev. Genet 16:405; U.S. Pat. No. 4.888.2741. The heteroduplex DNA can take several forms, including a three DNA strand containing triplex form wherein a single complementary strand invades the DNA duplex (see, for example,. Hsieh et al. (1990) Genes and Development 4:1951; Rao et al., (1991) PNAS 88:2984)) and, when two complementary DNA strands pair with a DNA duplex, a classical Holliday recombination joint or chi structure (Holliday, R. (1964) Genet. Res, 5: 282) can form, or a double-D loop (“Diagnostic Applications of Double-D Loop Formation” U.SPatent No. 5,273,881). Once formed, a heteroduplex structure can be resolved by strand breakage and exchange, so that all or a portion of an invading DNA strand is spliced into a recipient DNA duplex, adding or replacing a segment of the recipient DNA duplex. Alternatively, a heteroduplex structure can result in gene conversion, wherein a sequence of an invading strand is transferred to a recipient DNA duplex by repair of mismatched bases using fee invading strand as a template (see, for example, Genes, 3rd Ed (1987) Lewin, B., John Wiley, New York, N.Y.; Lopez et al. (1987) Nucleic Acids Res. 15: 5643). Whether by the mechanism of breakage and rejoining or by the mecbanism(s) of gene conversion, formation of heteroduplex DNA at homologously paired joints can serve to transfer genetic sequence information from one DNA molecule to another. A number of papers describe the use of homologous recombination in mammalian cells. Illustrative of these papers are Kucheriapati et ah (1984) Proc. Natl. Acad. Sei. USA 81:3153-3157; Kucheriapati et aL (1985) MoL Cell. Bio. 5:714-720; Smithies et al. (1985) Nature 317:230-234; Wake et al. (1985) Mol. Cell. Bio. 8:2080-2089; Ayares et al. (1985) Genetics 111:375-388; Ayares et al. (1986) MoL Cell, Bio. 7:1656-1662; Song et al. (1987) Proc. Natl. Acad. Sci. USA 84:6820-6824; Thomas et al. (1986) Cell 44:419-428; Thomas and Capecchi, (1987) Cell 51: 503-512; Nandi et al. (1988) Proc. Natl. Acad. Sci. USA 85:3845-3849; and Maasour et aL (1988) Nature 336:348-352; Evans and Kaufinan, (1981) Nature 294:146-154; Doetschman et al. (1987) Nature 330:576-578; Thoma and Capecchi, (1987) Cell 51:503-512; Thompson et al. (1989) Cell 56:316-321.

Cells useful for homologous recombination include, by way of example, epithelial cells, neural cells, epidermal cells, keratinocytes, hematopoietic cells, melanocytes, chondrocytes, lymphocytes (B and T lymphocytes), erythrocytes, macrophages, monocytes, mononuclear cells, fibroblasts, cardiac muscle cells, and other muscle cells, etc.

The vector construct containing the iRNA template may comprise a full or partial sequence of one or more exons and/or introns of the gene targeted for insertion, a full or partial promoter sequence of the gene targeted for insertion, or combinations thereof. In one embodiment of the invention, the nucleic acid sequence of the iRNA containing construct comprises a first nucleic acid sequence region homologous to a first nucleic add sequence region of the gene targeted for insertion, and a second nucleic acid sequence region homologous to a second nucleic acid sequence region of the gene targeted for insertion. The orientation of the vector construct should be such that the first nucleic acid sequence is upstream of the second, nucleic acid sequence and the iRNA template should be therebetween. A nucleic acid sequence regian(s) can be selected so that there is homology between the iRNA template containing vector construct soquence(s) and die gene of interest. Preferably, the construct sequences are isogenic sequences with respect to the target sequences. The nucleic acid sequence region of the construct may correlate to any region of the gene provided that it is homologous to the gene. A nucleic acid sequence is considered to be "homologous" if it is at least about 90% identical, preferably at least about 95% identical, or most preferably» about 98 % identical to the nucleic acid sequence. Furthermore, the 5' and 3' nucleic acid sequences flanking the selectable marker should he sufficiently large to provide complementary sequence for hybridization, when the construct is introduced into the genomic DNA of the target cell. For example, homologous nucleic acid sequences flanking the selectable marker gene should be at least about 500 bp, preferably, at least about 1 Miobase (kb), more preferably about 2-4 kb, and most preferably about 3-4 kb in length. In one embodiment, both of the homologous nucleic acid sequences flanking the selectable marker gene of the construct should be should be at least about 500 bp, preferably, at least about 1 kb, more preferably about 2-4 kb, and most preferably about 3-4 kb in length.

Another type of DNA. sequence can be a cDNA sequence provided the cDNA is sufficiently large. Each of the flanking nucleic acid sequences used to make the construct is preferably homologous to one or more exon and/or intron regions, and/or a promoter region.

Each of these sequences is different from the other, but may be homologous to regions within the same exon and/or intron. Alternatively, these sequences may he homologous to regions within different exons and/or interns of the gene. Preferably, the two flanking nucleic acid sequences of the construct are homologous to two sequence regions of the same or different interns of the gene of interest In addition, isogenic DNA can be used to make the construct of the present invention. Thus, the nucleic acid sequences obtained to make the construct are preferably obtained tern the same cell line as that being used as the target cell..

Alternatively, a targeting construct can he used in which a single region of homology is present. In such constructs, a single homologous cross-over event produces an insertion within the homolgous regions. This construct can either be supplied circular or is linear and spontaneously circularized within the cell via natural processes (Hasty P, Rivera-Peacez J, Chang C, Bradley A Target frequency and integration pattern for insertion and replacement vectors in embryonic stem cells. Mol Cell Biol. 1991 Sep;l 1(9):4509-17)..

In one embodiment of tire present invention, homologous recombination is used to insert an 1RNA containing expression vector qperably linked to a promoter into the genome of a cell, such as a fibroblast The DNA can comprise at least a portion of the gene at the particular locus with introduction of the expression vector into preferably at least one, optionally both copies, of the targeted gene.

Alternatively, an flRNA containing expression vector lacking a promoter can be inserted into an endogenous gene. The insertion allows expression of the promoterless vector to he driven by the endogenous gene’s associated promoter. In one embodiment, the vector is inserted the 3’ non-coding region of a gene, in a particular aspect of the invention, the vector is inserted into a tissue specific or physiologically specific gene. For example, hepatocyte specific expression is provided by targeting an endogenous gene that is expressed in every hepatocyte at the desired level and temporal pattern.

In another embodiment, a targeting vector is assembled such that the £RNA vector is inserted into a single allele of a housekeeping gene. Non limiting examples of targeted housekeeping genes include the conserved cross species analogs of the following human housekeeping genes; mitochondrial 16S rKNA, ribosomal protein L29 (RPL29), H3 histone, family 3B (H3.3B) (H3F3B), poly(A)-binjding protein, cytoplasmic 1 (PABPC1), HLA-B associated transcript-1 (D6S81E), surfeit 1 (SURF1), ribosomal protein L8 (RPL8), ribosomal protein L38 (RPL38), catechol-O-methyltransferase (COMT), ribosomal protein S7 (RPS7), heat shock 27kD protein 1 (HSPB1), eukaryotic translation elongation fee tor 1 delta (guanine nucleotide exchange protein) (EEF1D), vimentih (VIM), ribosomal protein L41 (RPL41), caiboxylesterase 2 (intestine, liver) (CES2), exportin 1 (CRM1, yeast, homolog) (XPOl), ubiquinol-cytochrome c reductase hinge protein (UQCRH), Glutathione peroxidase 1 (GPX1), ribophorin E (RPN2), Pleckstrin and Sec7 domain protein (PSD), human cardiac troponin T, proteasome (prosome, macropain) subunit, beta type, 5 (PSMB5), cofilin l (non-muscle) (CFL1), seryl-tRNA synthetase (SAKS), catenin (cadherin-associated protein), beta 1 (88kD) (CTNNB1), Duffy blood group (FY), erythrocyte membrane protein band 7.2 (stamatin) (EPB72), Fas/Apo-1, LIM and SH3 protein 1 (LASPI), accessory proteins BAP31/BAP29 (DXS1357E), nascent-polypeptide-associated complex alpha polypeptide (NACA), ribosomal protein L18a (RPL18A), TNF receptor-associated factor 4 (TRAF4), MLN51 protein (MLN51), ribosomal protein Lll (RPL11), Poly(iC}-bindmg protein 2 (PCBP2), thioredoxin (TXN), glntaminyl-tKNA synthetase (QARS), testis enhanced gene transcript (TEGT), prostatic binding protein (PBP), signal sequence receptor, beta (translocon-associated protein beta) (SSR2), ribosomal protein L3 (RPL3), centrin, EF-hand protein,2 (CETN2), heterogeneous nuclear ribonucleoprotedn K (HNRPK), glutathione peroxidase 4 (phospholipid hydroperoxidase) (GPX4), fusion, derived from t(12;16) malignant liposarcoma (FUS), ATP synthase, H+ transporting, mitochondrial FO complex, subunit c (subunit 9), isofoim 2 (ATP5G2), ribosomal protein S26 (RPS26), ribosomal protein L6 (RPL6), ribosomal protein S18 (RPS18), serine (or cysteine) proteinase inhibitor, clade A (alpha-1 antiproteioase, antitrypsin), member 3 (SBRPINA3), dual specificity phosphatase 1 (DUSP1), peroxiredoxin 1 (PRDX1), epididymal secretory protein (19.5kD) (HE1), ribosomal protein S8 (RPS8), translocated promoter region (to activated MET oncogene) (TFR), ribosomal protein L13 (RPL13), SON DNA binding protein (SON), ribosomal prot L19 (RPL19), ribosomal prot (homolog to yeast S24), CD63 antigen (melanoma 1 antigen) (CD63), protein tyrosine phosphatase, non-receptor type 6 (PTPN6), eukaryotic translation elongation factor 1 beta 2 (EEF1B2), ATP synthase, H+ transporting, mitochondrial FO complex, subunit b, isoform 1 (ATF5F1), solute carrier family 25 (mitochondrial carrier, phosphate earner), member 3 (SLC25A3), tryptophanyl-tRNA synthetase (WARS), glutamate-ammonia ligase (glutamine synthase) (GLUL), ribosomal protein L7 (RPL7 ), interferon induced transmembrane protein 2 (1-8D) (TFITM2), tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, beta polypeptide (YWHAB), Casein kinase 2, beta polypeptide (CSNK2B), ubiquitin A~52 residue ribosomal protein fusion product 1 (LJBA52), ribosomal protein L13a (RPL13A), major histocompatibility complex, class I, E (HLA-E), jun D proto-oncogene (JUND), tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, theta polypeptide (YWHAQ), ribosomal protein L23 (RPL23), Ribosomal protein S3 (RPS3 ), ribosomal protein L17 (RPL17), filamin A, alpha (actin-binding protein-280) (FLNA), matrix Gla protein (MGP), ribosomal protein L35a (RPL35A), peptidylprolyl isomerase A (cyclophilin A) ΓΡΡΙΑ), villin 2 (ezrin) (VTL2), eukaryotic translation elongation factor 2 (EEF2), jun B proto-oncogene (JUNB), ribosomal protein S2 (KPS2), cytochrome c oxidase subunit Vile (COX7Q, heterogeneous nuclear rfbomcieoprotein L (HNRPL), tumor protein, translaticually-controlled 1 (TPT1), ribosomal protein L31 (RPL31), cytochrome c oxidase subunit VHa polypeptide 2 (liver) (COX7AJ2), DEAD/H (Asp-Glu-Ala-Asp/His) box polypeptide 5 (RNA helicase, 68kD) (DDX5), cytochrome c oxidase subunit Via polypeptide 1 (COX6A1), heat shock 90kD protein 1, alplia (HSPCA), Sjogren syndrome antigen B (autoantigen La) (SSB), lactate dehydrogenase B (LDHB), high-mobility group (nonhistone chromosomal) protein 17 (HMG17), cytochrome c oxidase subunit Vic (COX6C), heterogeneous nuclear ribonucleoprotein Al (HNRPA1), aldolase A, fructose-bispho sphate (ALDOA), integrin, beta 1 (fihronectin receptor, beta polypeptide, antigen CD29 includes MDF2, MSK12) (ITGB1), ribosomal protein SI 1 (RPS11), small nuclear ribonucleoprotein 70kD polypeptide (RN antigen) (SNRP20), guanine nucleotide binding protein (G protein), beta polypeptide 1 (GNB1), heterogeneous nuclear ribonucleoprotein Al (HNRPA1), calpain 4, small subunit (30K) (CAPN4), elongation factor TU (N-terminus)/X03689, ribosomal protein 132 (RPL32), major histocompatibility complex, class Π, DP alpha 1 (HLA-DPA1), superoxide dismutase 1, soluble (amyotrophic lateral sclerosis 1 (adult)) (SOD1), lactate dehydrogenase A (LDHA), glyceraldehyde-3-ph.osphate dehydrogenase (GAPD), Actin, beta (ACTB), major Mstocompatibiiity complex, class Π, DP alpha (HLA-DRA), tubulin, beta polypeptide (TUBB), metalloiMonein 2A (MT2A), phosphoglycerate kinase 1 (PGK1), KRAB-associated protein 1 (IIF1B), eukaryotic translation initiation factor 3, subunit 5 . (epsilon, 47KD) (EIF3S5), NADH dehydrogenase (ubiquinone) 1 alpha subcomplex, 4 (9kD, MURQ) (NDUFA4), chloride intracellular channel 1 (CLIC1), adaptor-related protein complex 3, sigma 1 subunit (AP3S1), cytochrome c oxidase subunit IV (COX4), PDZ and L3M domain 1 (elfin) (PDLIM1), glutaihione-S-transferase like; glutathione transferase omega (GSTTLp28), interferon stimulated gene (20kD) (ISG20), nuclear factor I/B (NFIB), COXIO (yeast) homolog, cytochrome c oxidase assembly protein (heme A: fkmesyltraxisferase), conserved gene amplified in osteosarcoma (OS4), deoxyhypusine synthase (DHPS), galactosidase, alpha (GLA), microsomal glutathione S-transferase 2 (MGST2), eukaryotic translation initiation factor 4 gamma, 2 (EIF4G2), ubiquitin carrier protein E2-C (UBCH10), BTG family, member 2 (BTG2), B-cell associated protein (RBA), COP9 subunit 6 (MOV34 homolog, 34 kD) (MOV34-34KD), ATX1 (antioxidant protein 1, yeast) homolog 1 (ATOX1), acidic protein rich in leucines (SSP29), poly(A)-binding prot (PABP) promoter region, selenoprotein W, 1 (SEPW1), eukaryotic translation initiation factor 3, subunit 6 (48kD) (EIF3S6), carnitine palmitoyltransferase I, muscle (CPT1B), transmembrane trafficking protein (TMP21), four and a half LIM domains 1 (FHL1), ribosomal protein S28 (RPS28), myeloid leukemia factor 2 (MLF2), neurofilament triplet L prot/LJ57341, capping protein (actin filament) muscle Z-line, alpha 1 (CAPZA1), 1-acylglycerol-3-phosphate O-acyltransferase 1 (lysophosphatidic acid acyltransferase, alpha) (AGPAT1), inositol 1,3,4-triphosphate 5/6 kinase (ΓΓΡΚ1), histidine triad nucleotide-binding protein (HINT), dynamitin (dynactin complex 50 kD subunit) (DCIN-50), actin related protein 2/3 complex, subunit 2 (34 kD) (A3SPC2), histone deacetylase 1 (HDAC1), ubiquitin B, chitinase 3-like 2 (CHBL2), D-dopacbtrome tautomerase (DDT), zinc finger protein 220 (ZNF220), sequestosome 1 (SQSTM1), cystatin B (stefin B) (CSTB), eukaryotic translation initiation factor 3, subunit 8 (110kD) (E1F3S8), chemokine (C-C motif) receptor 9 (CCR9), ubiquitin specific protease 11 (USP11), laminin receptor 1 (67kD, ribosomal protein SA) (LAMR1), amplified in osteosarcoma (OS-9), splicing factor 3b, subunit 2,145KD (SF3B2), integrin-liuked kinase (ILK.), ubiquitin-conjugating enzyme E2D 3 (homologous to yeast UBC4/5) (UBE2D3), chaperonin containing TCP l, subunit 4 (delta) (CCT4), polymerase (RNA) Π (DNA directed) polypeptide L (7.6kD) (POLR2L), nuclear receptor co-repressor 2 (NCOR2), accessory proteins BAP31/BAP29 (DXS1357B, SLC6A8), 13kD differentiation-associated protein (LOC55967), Taxi (human T-cell leukemia virus type 1) binding protein 1 (TAX1BP1), damage-specific DNA binding protein 1 (127fcD) (DDB1), dynein, cytoplasmic, light polypeptide (PIN)» metirionine aminopeptidase; eIF-2-associated p67 (MNPEP), G protein pathway suppressor 2 (GPS2), ribosoxnal protein L21 (RPL21), coatomer protein complex, subunit alpha (COPA), G protein pathway suppressor 1 (GPS1), small nuclear nbonucleoprotein D2 polypeptide (16.5kD) (SNRPD2), ribosomal protein S29 (RPS29), ribosomal protein S10 (EPSIO), ribosomal proteinS9 (RPS9), ribosomal protein S5 (RPS5), ribosomal protein L28 (RPL28), ribosomal protein L27a (RPL27A), protein tyro sine phosphatase type IVA, member 2 (PTP4A2), ribosomal prot 136 (RPL35), ribosomal protein LlOa (RPL10A), Fc fragment of IgG, receptor, transporter, alpha (FCGRT), maternal G10 transcript (G10), ribosomal protein L9 (RPL9), AXP synthase, H+ transporting, mitochondrial FO complex, subunit c (subunit 9) isoform 3 (ATP5G3), signal recognition particle 14kD (homologous Ain RNA-binding protein) (SRP14), mntL (E. coli) homolog 1 (colon cancer, nonpolyposis type 2) (MLH1), chromosome lq subtelomeric sequence D1S5537U06155, fibromodulm (FMOD), anrino-tenmnal enhancer of split (AES), Rho GTPase activating protein 1 (ARHGAP1), non-POU-domLam-containing, octamer-binding (ΝΟΝΟ), v-raf murine sarcoma 3611 viral oncogene homolog 1 (ARAF1), heterogeneous nuclear ribonucleoprotem Al (HNRPA1), beta 2-microglobuliii (B2M), ribosomal protein S27a (RPS27A), bromodomain-containing 2 (BRD2), azoospermia factor 1 (AZF1), upregulated by 1,25 dihydroxyvitamin D-3 (VDUP1), serine (or cysteine) proteinase inhibitor, clade B (ovalbumin), member 6 (SERPINB6), destrin (actiba depolymerizing factor) (ADF), thymosin beta-10 (TMSB10), CD34 antigen (CD34), spectrin, beta, nom-erythrocytie 1 (SPTBN1), angio-associated, migratory cell protein (AAMP), major tastocorapatibflity complex, class Σ, A (HLA-A), MYC-associated zinc finger protein (purine-binding transcription factor) (MAZ), SET translocation (myeloid leukemia-associated) (SET), paired box gene(aniridia, keratitis) (PAX6), zinc finger protean homologous to Zfp-36 in mouse (ZFP36), FK506-bindiag protein 4 (59kD) (FKBP4), nucleosome assembly protein 1-like 1 (NAP1L1), tyrosine 3-monooxygenase/tryptophaa 5-monooxygenase activation protein, zeta polypeptide (YWHAZ), ribosomal protdn S3A (RPS3A.), ADP-ribosyiation factor 1, ribosomal protein S19 (RPS19), transcription elongation factor A (SB), 1 (TCEA1), ribosomal protein S6 (RPS6), ADP-ribosylarion factor 3 (ARF3), moesin (MSN), nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (NFKBIA), complement component 1, q subcomponent binding protein (C1QBP), ribosomal protein S25 (RPS25), clusterm (complement lysis inhibitor, SP-40,40, sulfated glycoprotein 2, testosterone-repressed prostate message 2, apolipoprotein. 1) (CLU), nucleolin (NCL), ribosomal protein S16 (RPS16), ubiqmtin-activating enzyme El (A1S9T and BN75 temperature sensitivity complementing) (UBE1), lectin, galactoside-binding, soluble, 3 (galectin 3) (LGAJLS3), eukaryotic translation elongation factor 1 gamma (EEF1G), pim-1 oncogene (PIM1), SI 00 calcium-binding protein A10 (annexm. H ligand,calpactm I, light polypeptide (pi 1)) (S100A10), H2A histone family, member Z (H2AFZ), ADP-iibosylation factor 4 (ARF4) (ARF4), ribosomal protein L7a (RPL7A), major histoconpatibility complex, class Π, DQ alpha 1 (HLA-DQA1), EK506-binding protein 1A (12kD) (FKBP1A), CD81 antigen (target of antiproliferative antibody 1) (CD81), ribosomal protein S15 (RPS15), X-box binding protein 1 (XBP1), major Mstoeompatibility complex, class Π, DN alpha (HLA-DNA), ribosomal protein S24 (RPS24), leukemia-associated phosphoproteia pi 8 (staffcrnin) (LAP 18), myosin, heavy polypeptide 9, non-muscle (MYH9), casein, kinase 2, beta polypeptide (CSNK2B), fecosidase, alpha-L- 1, tissue (FUCA1), diaphorase (NADH) (cytochrome b-5 rednctase) (DIA1), cystatin C (amyloid angiopathy and cerebral hemorrhage) (CST3), ubiquifcin C (UBC), ubiquiaol-cytochrome c reductase binding protein (UQCRB), prothymosin, alpha (gene sequence 28) (PTMA), glutathione S-transferase pi (GSTP1), guanine nucleotide binding protean (G protein), beta polypeptide 2-like 1 (GNB2L1), nucleophosmin (nucleolar phosphoprotein B23, numatrin) (NPM1), CD3E antigen, epsilon polypeptide (ΤΪΓ3 complex) (CD3E), calpain 2, (m/Π) large subunit (GAPN2), NADH dehydrogenase (ubiquinone) flavoprotein 2 (24kD) (NDUFV2), heat shock 601cD protein 1 (chaperonin) (HSPD1), guanine nucleotide binding protein (G protein), alpha stimulating activity polypeptide 1 (GNAS1), clathrin, light polypeptide (Lea) (CLTA), ATP synthase, H+ transporting, mitochondrial FI complex, beta polypeptide, calmodulin 2 (phosphorylase kinase, delta) (CALM2), actin, gamma 1 (ACTG1), ribosomal protein S17 (RPS17), ribosomal protein, large, PI (RPLP1), ribosomal protein, large, P0 (RPLPO), thymosin, beta 4, X chromosome (TMSB4X), heterogeneous nuclear ribonucleoprotem C (C1/C2) (HNRPC), ribosomal protein L36a (RPL36A), glucuronidase, beta (GUSB), FYN oncogene related to SRC, FGR, YES (FYN)» prothymosin, alpha (gene sequence 28) (PTMA), enolase 1, (alpha) (ENOl), laminin receptor 1 (67kD, ribosomal protein SA) (LAMR1), ribosomal protein S14 (RPS14), CD74 antigen (invariant polypeptide of major histocompatibility complex, class Π antigen-associated), esterase D/fermylglutathione hydrolase (BSD), H3 histone, family 3A (H3F3A), ferritin, light polypeptide (FTL), Sec23 (S. cerevisiae) homolog A (SEZ23A), actin, beta (ACTB), presemlin 1 (Alzheimer disease 3) (PSEN1), interieuMn-l receptor-associated kinase 1 (IRAKI), zinc finger protein 162 (ZNF162), ribosomal protein L34 (RPL34), beclin 1 (coiled-coil, myosin-like BCL2-interacting protein) (BECN1), phosphatidylinositol 4-kinase, catalytic, alpha polypeptide (PIK4CA), IQ motif containing GTPase activating protein 1 (IQGAP1), signal transducer and activator of transcription 3 (acute-phase response factor) (STAT3), heterogeneous nuclear ribonucleoprotein F (HNRPF), putative translation initiation factor (STILL), protein translocation complex beta (SEC61B), ras homolog gene family, member A (ARHA), ferritin, heavy polypeptide 1 (FTH1), Rho GDP dissociation inhibitor (GDI) beta (ARKGDIB), H2A histone family, member 0 (H2AFO), annexin A11 (ANXA11), ribosomal protein L27 (RPL27), adenylyl cyclase-associated protein (CAP), zinc finger protein 91 (HPF7, HTF10) (ZNF91), ribosomal protein LIS (RPL18), famesyltransferase, CAAX box, alpha (FNTA), sodium channel, voltage-gated, type I, beta polypeptide (SCN1B), calnesrin (CANX), proteolipid protein 2 (colonic epithehum-enriched) (PLP2), amyloid beta (A4) precursor-like protein 2 (APLP2), Voltage-dependent anion channel 2, proteasome (prosome, macropain) activator subunit 1 (PA28 alpha) (PSMB1), ribosomal prot L12 (RPL12), ribosomal protein L37a (RPL37A), ribosomal protein S21 (RJPS21), proteasome (prosome, macropain) 26S subunit, ATPase, 1 (PSMC1), major histocompatibility complex, class Π, DQ beta 1 (HLA-DQB1), replication protein A2 (32kD) (RPA2), heat shock 90kD protein 1, beta (HSPCB), cytochrome c oxydase subunit VM (C0X8), eukaryotic translation elongation factor 1 alpha 1 (EBF1A1), SNRPN upstream reading frame (SNURF), lectin, galactoside-binding, soluble, 1 (galectin 1) (LGALS1), lysosomal-associated membrane protein 1 (LAMP1), phosphoglycerate mutase 1 (brain) (PGAM1), interferon-induced transmembrane protein 1 (9-27) (ΠΤΤΜ1), nuclease sensitive element binding protein 1 (NSEP1), solute carrier family 25 (mitochondrial carrier, adenine nucleotide translocator), member 6 (SLC25A6), ADP-ribosyltransferase (NAD+; poly (ADP-ribose) polymerase) (ADPRT), leukotriene A4 hydrolase (LTA4H), profihn 1 (PFN1), prosaposin (variant Gaucher disease and variant metachromatic leukodystrophy) (PSAP), solute carrier family 25 (mitochondrial carrier, adenine nucleotide translocator), member 5 (SLC25A5), beta-2 microglobulin, insulin-like growth factor binding protein 7, Ribosomal prot S13, Epstein-Barr Virus Small Rna-Associated prot, Major Histocompatibility Complex, Class 3, C X58536), Ribosomal prot S12, Ribosomal prot L10, Transformation-Related prot, Ribosomal prot L5, Transcriptional Coactivator Pc4, Cathepsin B, Ribosomal prot L26, "Major Histocompatibility Complex, Class I X12432", Wilm S Tumor-Related prot, Tropomyosin Tm30mn Cytoskeletal, liposomal Protein S4, X-Linked, Ribosomal prot L37, Metallopanstimulin 1, Ribosomal prot L30, Heterogeneous Nuclear Ribonucleoprot K, Major Histocompatibility Complex, Class I, E M21533, Major Histocompatibility Complex, Class I, E M20Q22, Ribosomal protein L30 Homolog, Heat Shock prot 70 Kda, "Myosin, Light Chain/U02629", "Myosin, Light Chain/U02629',> Calcyclin, Single-Stranded Dma-Binding prot Mssp-1, Triosephospbafe Lsomerase, Nuclear Mitotic Apparatus prot 1, prot Kinase Ht31 Camp-Dependent, Tubulin, Beta 2, Calmodulin Type I, Ribosomal prot S20, Transcription Factor BtBb, Globin, Beta, Small Nuclear RjbcmucleoproteanPolypeptide CAlt Splice 2, Nucleoside Diphosphate Kinase Nru23-H2s, Ras-Related C3 Botulinum Toxin Substrate, activating transcription factor 4 (tax-responsive enhancer element B67) (ATF4), prefoldin (PFDN5), N-myc downstream regulated (NDRG1), ribosomal protein L14 (RPL14)3 nicastrin (K1AA0253), protease, serine, 11 (IGF binding) (PRSS11), KIAA0220 protein (KIAA0220), dishevelled 3 (homologous to Drosophila dsh) (DVL3), enhancer of rudimentary Drosophila homolog (ERH), SNA-binding protein gene with multiple splicing (RBPMS), 5-anttnoiraidazole-4-carboxamide ribonucleotide formyltransferase/MP cyclolhydrolase (ATIC), KIAA0164 gene product (KIAA0164), ribosomal protein L39 (RPL39), tyrosine 3 monooxygenase/tryptophan 5-monooxygenase activation protein, eta polypeptide (Y1VHAH), Ornithine decarboxylase antizyme 1 (OAZ1), proteasome (prosome, macropain) 26S subunit, non-ATPase, 2 (PSMD2), cold inducible RNA-binding protein (CIRBP), neural precursor cell expressed, developmeatally down-regulated 5 (NEDD5), Hgh-mobility group nonhistone chromosomal protein 1 (HMG1), malate dehydrogenase 1, NAD (soluble) (MDH1), cyclin I (CCNI), proteasome (prosome, macropain) 26S subunit, non-ATPase, 7 (Mov34 itcanolog) (PSMD7), major histocompatibility complex, class 1, B (HLA-B), ATPase, vacuolar, 14 kD (ATP6S14), transcription factor-like 1 (TCFL1), KIAA0084 protein (KIAA0084), proteasome (prosome, macropain) 26S subunit, non-ATPase, 8 (PSMD8), major histocompatibility complex, class L A (HIA-A), aknyl-tKNA synthetase (AARS), lysyl-tKNA synthetase (KARS), ADP-ribosylaticm factor-like 6 interacting protein (ARL6IP), KIAA0063 gene product (K1AA0063), actin binding LIM protein 1 (ABLIM), DAZ associated protein 2 (DAZAP2), eukaryotic translation jnitiation factor 4A, isofonn 2 (EIF4A2), CD151 antigen (GD151), proteasome (prosome, macropain) subunit, beta type, 6 (PSMB6), proteasome (prosome, macropain) subunit, beta type, 4 (PSMB4), proteasome (prosome, macropain) subunit, beta type, 2 (PSMB2), proteasome (prosome, macropain) subunit, beta type, 3 (PSMB3), Williams-Beuren syndrome chromosome region 1 (WBSCR1), ancient ubiquitous protein 1 (AUP1), KIAA0864 protein (KIAA0864), neural precursor cell expressed, developmeatally down-regulated 8 (NEDD8), ribosomal protein L4 (KPL4), KIAA0111 gene product (KIAA0111), transgelin 2 (TAGLN2), Clathrin, heavy polypeptide (He) (CLTC, CLTCL2), ATP synthase, H-f transporting, mitochondrial

Fleomplex, gamma polypeptide 1 (ATP5C1), calpastatin (CAST), MQRF-related gene X (KIA0026), ATP synthase, H+ transporting, nritochandrial FI complex, alpha subunit, isofcom 1, cardiac muscle (ATP5A1), phosphatidyiseriae synthase 1 (PTDSS1), anti-oxidant protein. 2 (non-selenium glutathione peroxidase, acidic calciurn-independent phospholipase A2) (KIAA0106), K3AA01O2 gene product (KIAA0102), ribosomal protein S23 (RPS23), CD164 antigen, sialomucin (CD164), GDP dissociation inhibitor 2 (GDI2), enoyl Co enzyme A hydratase, short chain, 1, mitochondrial (ECHS1), eukaryotic translation initiation factor 4A, isoform 1 (EIF4A1), cyclin D2 (CCND2), heterogeneous nuclear ribonucleoprotein U (scaffold attachment fector A) (HNRPU), APEX nuclease (multifunctional DNA repair enzyme) (APEX), ATP synthase, H+ transporting, mitochondrial FO complex, subunit c (subunit 9), isoform 1 (ATP5G1), myristoylated alanine-rich protein kinase C substrate (MAR.CKS, 80K-L) (MACS), annexin A2 (ANXA2), similar to S. cerevisiae RER1 (TRER1), hyalnronoglucosaminidase 2 (HYAL2), uroplakin 1A (UPK1A), nuclear pore complex interacting protein (KPIP), karyopherin alpha 4 (importin alpha 3) (KPNA4), ant the gene with multiple splice variants near HD locus on 4pl6.3 (RES4-22).

In one embodiment an iRNA template containing vector is inserted into a targeted housekeeping gene within an intron of the target housekeeping gene, in one sub-embodiment, the target housekeeping gene is prevented from being translated by insertion of a promoterless engineered iRNA template that contains multiple stop codons in the 3’ end of the construct within an intron of the target gene. Using this promoter-tap' strategy, the iRNA construct is spliced into the chromosome, potentially in frame with the upstream of the exon comprising the target gene. This results in the expression of the iRNA template prior to the targeted housekeeping gene. In some embodiments, the iRNA template expression concomitantly inhibits expression of the housekeeping gene duB to the presence of multiple stop codons downstream of the iRNA template. Furthermore, expression of the iRNA template is under control of the endogenous housekeeping gene promoter. For such a “promoter-trap” strategy, a housekeeping gene targeting construct is designed which contains a sequence with homology to an intron sequence of the target housekeeping gene, a downstream intron splice acceptor signal sequence comprising the AG dinucleotide splice acceptor site, a promoteriess iRNA template engineered to contain multiple stop codons 3’ of the iRNA tempalte, the intron splice donor signal sequence comprising the GT dinucleotide splice donor site for splicing the engineered iRNA template to the immediate downstream exon, and additional sequence with homology to the intron sequence of Ihe target gene to aid with annealing to the target gene. Ια another embodiment, the 'promoter trap' strategy is used, to Insert the iRNA template containing vector in the target housekeeping gene by replacing an endogenous housekeeping exon with an in-frame, promoterless iRNA template containing vector. The iRNA template containing vector is spliced into the chromosome and results in the expression of die iRNA template and concomitant inhibited expression of the foil-length target housekeeping gene. Further, the iRNA template is under the control of the housekeeping gene’s associated promoter.

This ‘promoter tap’ gene targeting construct may be designed to contain a sequence with homology to the target housekeeping gene 3’ intron sequence upstream of the start codon, the upstream intron splice acceptor sequence comprising the AG dmucleoti.de splice acceptor site, a Kozak consensus sequence, a promoterless iRNA template containing vector containing e.g., a polyA termination, sequence, a splice donor sequence comprising the GT dinucleotide splice donor site from a intron region downstream of the start codon, and a sequence with 5’ sequence homology to the downstream intron. It will be appreciated that the method maybe used to target any exon within the targeted housekeeping gene.

In one embodiment, the DNA is randomly inserted into the chromosome and is designed to signal its presence via the activation of a reporter gene, which both mimics the expression of the endogenous gene and potentially mutates the locus. By selecting in cell culture those cells in which the reporter gene has been activated, animals can be generated for more quickly than by conventional gene mutation because there is no need to target each gene separately.

In another embodiment, the iRNA involves the tansgene expression of a vector containing iRNA opexably bilked to a promoter through the use of an Epstein-Baxr Virus (EBV) mini-chromosome vector. A number of papers discuss the use of EBV mini-chromosomes for tansgene expression of vectors (see, for example, Saeki Y et al. (1998) Hitman Gene Therapy 10:2787-2794; SaeM Y et al (1998) Gene Therapy 5:1031-1037).

In embodiments of the present invention, linearized vectors or synthetic oligonucleotides that contain 5’ and 3’ recombination arms and a DNA template emcodmg iRNA are provided. In one embodiment, these targeting constructs can be inserted into an exon or intron of an endogeous gene withour disrupting foe expression of the endogenous gene. In another emodiment, foe siRNA template is embedded within a self-contaiained, sequence that is capable of functional as an intron. The siRNA-containing intron is then inserted into an exon of an endogenous gene such that the resulting recombination allows siRNA expression under the control of the endogenous gene regulatory elements and does not prevent expression and translation of the same endogenous gene.

In another embodiment, the targeting construct can be inserted into a gene and render the gene inactivated, “knock-out” the gene. In particular embodiments of the present invention, die targeting constructs produced according to the methods described herein can knockout xenoantigenic genes, such as alpha-1,3-galactosyltransferase (such as described in Phelps, et al.> Science, 299: pp. 411·414 (2003) or WO 2004/028243). Additional genes that are considered potential barriers to xenotransplanataion and thus can be targeted include: the porcine iGb3 synthase gene (see, for example, USSN 60/517,524), the CMP-Neu5Ac hydroxylase gene (see, for example, USSN 10/863,116), and/or the Farssman synthase gene (see, for example, U.S. Patent Application 60/568,922). In particular embodiments, the targeting constructs described herein can contain 5’ and 3’ targeting arms that are homologous to gene sequence encoding one or more of these xenoantigens. In other embodiment, heterozygous and/or homozygous knockouts can be produced. In a particular embodiment, the targeting constructs produced according to the methods described herein can produce iRNA molecules that repress the expression of PER.V I porcine cells and knockout at least one xeno antigen.

In other embodiments, the vectors or synthetic oligoncleotide contracts encoding the iRNA molecules can also include a selectable marker gene. The selectable marker gene can fused in reading flame with the upstream sequence of the target gene. In other embodiments, the cells can be assayed functionally to determine whether successful targeting has occurred. In further embodiments, the cells can be analyzed bu restriction analysis, electrophoresis, Southern analysis, polymerase chain reaction, sequencing or another technique known in the art to determine whether appropriate integration of the DNA encoding die iRNA molecules has occurred

Suitable selectable marker genes include, but are not limited to: genes conferring the ability to grow on certain media substrates, such as the tk gene (thymidine kinase) or the hprt gene (hypoxanthine phosphoribosyltramferase) which confer the ability to grow on HAT medium (hypoxanthine, ammopterin and thymidine); the bacterial gpt gene (guanine/xantbine phosphoribosyltransferase) which allows growth on MAX medium (mycophenolic add, adenine, and xanthine). See Song et aL, Proc. Natl Acad. Sci. U.S A. 84:6820-6824 (1987). See also Sambrook et al., Molecular Cloning-A Laboratory Manual, Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y. (1989), see chapter 16. Other examples of selectable markers include: genes conferring resistance to compounds such as antibiotics, genes conferring the ability to grow on selected substrates, genes encoding proteins that produce detectable signals such, as luminescence, such as great fluorescent protein, enhanced green fluorescent protein (eGFP). A wide variety of such markers are known and available, including, for example, antibiotic resistance genes such as the neomycin resistance gene (neo), Southern, P., and P. Berg, J. Mol. Appl. Genet. 1:327-341 (1982); and the hygromycin resistance gene (hyg), Nucleic Acids Research 11:6895-6911 (1983), and Te Riele et al., Nature 348:649-651 (1990). Other selectable marker genes include: acetohydroxy acid synthase (AHAS), alkaline phosphatase (AP), beta galactosidase (LacZ), beta glucoronidase (GUS), chloramphenicol acetyltransferasc (CA1), green fluorescent protein (GFP), red fluorescent protein (RFP), yellow fluorescent protein (YFP), cyan fluorescent protein (CFP), horseradish peroxidase (KRP), huaferase (Luc), nopaline synthase (NOS), octopine synthase (OCS), and derivatives thereof Multiple selectable markers are available that confer resistance to ampicillin, bleomycin, chloramphenicol, gentamycin, hygromycin, kanamycin, lincomycin, methotrexate, phosphinothricin, puromycin, and tetracycline.

Methods for the incorporation of antibiotic resistance genes and negative selection factors will be familiar to those of ordinary skill in the art (see, e.g., WO 99/15650; U.S. Patent No. 6,080,576; U.S. Patent No. 6.136,566; Niwa, et al., J Biochem. 113:343-349 (1993); and Yoshida, et al., Transgenic Research, 4:277-287 (1995)).

Additional selectable marker genes useful in this invention, for example, are described in U.S. Patent Nos: 6,319,669; 6,316,181; 6,303,373; 6,291,177; 6,284,519; 6,284,496; 6,280,934; 6,274,354; 6,270,958; 6,268,201; 6,265,548; 6,261,760; 6,255,558; 6,255,071; 6,251,677; 6,251,602; 6,251,582; 6,251,384; 6,248,558; 6,248,550; 6,248,543; 6,232,107; 6,228,639; 6,225,082; 6,221,612; 6,218,185; 6,214,567; 6,214,563; 6,210,922; 6,210,910; 6,203,986; 6,197,928; 6,180,343; 6,172,188; 6,153,409; 6,150,176; 6,146,826; 6,140,132; 6,136,539; 6,136,538; 6,133,429; 6,130,313; 6,124,128; 6,110,711; 6,096,865; 6,096,717; 6,093,808; 6,090,919; 6,083,690; 6,077,707; 6,066,476; 6,060,247; 6,054,321; 6,037,133; 6,027,881; 6,025,192; 6,020,192; 6,013,447; 6,001,557; 5,994,077; 5,994,071; 5,993,778; 5,989,808; 5,985,577; 5,968,773; 5,968,738; 5,958,713; 5,952,236; 5,948,889; 5,948,681; 5,942,387; 5,932,435; 5,922,576; 5,919,445; and 5,914,233. Combinations of selectable markers can also be used.

Cells that have been homologously recombined to introduce DNA encoding iRNA molecules into file genome can then be grown in appropriately-selected medium to identify cells providing the appropriate integration. Those cells which show the desired phenotype can then be farther analyzed by restriction analysis, electrophoresis, Southern analysis, polymerase chain reaction, or another technique known in the art. By identifying fragments which show the appropriate insertion at the target gene site, cells can be identified in which homologous recombination, has occurred.

Calls which show the desired phenotype based on expression of iENA molecules can then he further analyzed by restriction analysis, electrophoresis, Southern analysis, polymerase chain reaction, etc to analyze the DNA in order to establish whether homologous or non-homologous recombination occurred. This can be determined by employing probes for the insert and then sequencing fee 5’ and 3' regions flanking fee insert for fee presence of fee DNA template encoding fee iRNA molecule extending beyond fee flanking regions of fee construct. Primers can also be used which are complementary to a sequence within fee construct and complementary to a sequence outside fee construct and at the target locus, hi this way, one can only obtain DNA duplexes having both of fee primers present in the complementary chains if homologous recombination has occurred. By demonstrating fee presence of the primer sequences or fee expected size sequence, fee occurrence of homologous recombination is supported.

The polymerase chain reaction used for screening homologous recoiribination events is described in Kim and Smithies, Nucleic Acids Res. 16:8887-8903,1988; and Joyner et al., Nature 338:153-156,1989. The combination of a mutant polyoma enhancer and a thymidine kinase promoter to drive fee neomycin gene has been shown to be active in both embryonic stan cells and EC cells by Thomas and CapeceM, supra, 1987; Nicholas and Berg (1983) in Teratocarcinoma Stem. Cell, eds. Siver, Martin and Strikland (Cold Spring Harbor Lab., Cold Spring Harbor, N.Y. (pp. 469-497); and Liirney andDonerly, Cell 35:693-699, (1983).

The cell lines obtained from fee first round of targeting are likely to be heterozygous for the targeted allele. Homozygosity, in which both alleles are modified, can be achieved in a number of ways. One approach is to grow up a number of cells in which one copy has been modified and then to subject these cells to another round of targeting using a different selectable marker. Alternatively, homozygotes can be obtained by breeding animals heterozygous for fee modified allele, according to traditional Mendelian genetics. In some situations, it can be desirable to have two different modified alleles. This can he achieved by successive rounds of gene targeting or by breeding heterozygotes, each of which carries one of fee desired modified alleles. IV. Genes Regulated/Targeted by iRNA molecules.

In a further aspect of the present invention, iRNA molecules that regulate the expression of specific genes or family of genes are provided, such that the expression of tire genes can be functionally eliminated, hi one embodiment, at least two iRNA molecules are provided that target the same region of a gene. In another embodiment, at least two iRNA molecules are provided that target at least two different regions of the same gene. In a further embodiment, at least two iRNA molecules are provided that target at least two different genes. Additonal embodiments of the invention provide combinations of the above strategies for gene targeting.

In one embodiment, die iRNA molecules can be the same sequence. In an alternate embodiment, the iRNA molecules can be different sequences. In another embodiment, the iRNA molecules can be integrated into either the same or different vectors or DNA templates. In one embodiment, the iRNA molecules within the vector or DNA template are operably linked to a promoter sequence, such as, for example, a ubiquitously expressed promoter or cell-type specific promoter. In another embodiment, the iRNA molecules within the vector or DNA template are not under the control of a promoter sequence. In a further embodiment, these vectors or DNA templates can be introduced into a cell. In one embodiment, the vector or DNA template can integrate into the genome of the cell. The integration into die cell can either be via random integration or targeted integration. The targeted integration can be via homologous recombination.

In other embodiments, at least two iRNA molecules are provided wherein the families of one or more genes can be regulated by expression of die iRNA molecules. In another embodiment, at least three, four ox five iRNA molecules are provided wherein the families of one or more genes can be regulated by expression of the iRNA molecules. The iRNA molecule can be homologous to a conserved sequence within one or more genes. The family of genes regulated using such methods of the invention can be endogenous to a cell, a family of related viral genes, a family of genes that are conserved within a viral genus, a family of related eukaryotic parasite genes, or more particularly a family of genes from a porcine endogenous retrovirus. In one specific embodiment, at least two iRNA molecules can target the at least two different genes, which are members of tire same family of genes. The iRNA molecules can target homologous regions within a family of genes and thus one iRNA molecule can target the same region of multiple genes.

The iRNA molecule can be selected from, but not limited to the following types of iRNA: antisense oligonucleotides, ribozyxnes, small interfering RNAs (siRNAs), double stranded RNAs (dsRNAs), inverted repeats, short hairpin RNAs (shRNAs), small temporally regulated RNAs, and clustered inhibitory RNAs (ciRNAs), including radial clustered inhibitory RNA, asymmetric clustered inhibitory RNA, linear clustered inhibitory RNA, and complex or compound clustered inhibitory RNA

In another embodiment, expression of iRNA molecules for regulating target genes in mammalian cell lines or transgenic animals is provided such that expression of the target gene is fractionally eliminated or below detectable levels, i.e. the expression of the target gene is decreased by at least about 70%, 75%, 80%, 85%, 90%, 95%, 97% or 99%.

In another embodiment of this aspect of the present invention, methods are provided to produce cells and animals in which interfering RNA molecules ate expressed to regulate the expression of target genes. Methods according to dais aspect of die invention can. comprise, for example: identifying one or more target nucleic acid sequences in a cell; obtaining at least two iRNA molecules that bind to the target nucleic arid sequences); introducing the iRNA molecules, optionally packaged in an expression vector, into the cell; and expressing the iRNAs in the ceil under conditions such that the iRNAs bind to the target nucleic arid sequences, thereby regulating expression of one or more target genes. In one entoodiment, the present invention provides methods of producing non-human transgenic animals that heritably express at least two iRNA molecules that regulate the expression of one or more target genes. In one embodiment, die animals can be produced via somatic cell nuclear transfer. The somatic cell can be engineered to express die iRNA molecule by any of the techniques described herein.

In other embodiments, the present invention also provides methods for the expression of at least two iRNA molecules in a cell or a transgenic animal, where dm iRNA targets a common location within a family of genes. Such methods can include, for example: identifying one or more target nucleic acid sequences in the cell that are homologous regions within a family of genes; preparing at least two iRNA molecules that bind to the target nucleic arid sequence(s); introducing the iRNA molecules, optionally packaged in an expression vector, into the cell; and expressing iRNAs in the cell or animal under conditions such that the iRNA molecules bind to the homologous region within the gene family.

The present invention also provides transgenic non-human animals produced by the methods of the invention. The methods of the invention are useful for the production of transgenic non-human mammals (e.g. mice, rats, sheep, goats, cows, pigs, rabbits, dogs, horses, mules, deer, cats, monkeys and other non-human, primates), birds (particularly chickens, ducks, and geese), fish, reptiles, amphibians, worms (e. g. C. elegams), and insects (including but not limited to, Mosquitos, Drosophila, Trichoplusa, and Spodoptera). While any species of non-human animal can be produced, in one embodiment the non-human anrmak axe transgenic pigs. The present invention also provides cells, tissues and organs isolated from such non-human transgenic animals. hi embodiments of the present invention, endogenous genes that can be regulated by the expression of at least two £RNA molecules include, but are not limited to, genes required for cell survival or cell replication, genes required for viral replication, genes that encode an immunoglobulin locus, for example, Kappa light chain, and genes that encode a cell surface protein, for example, Vascular Cell Adhesion Molecule (VCAM) and other genes important to the structure and/or function of cells, tissues, organs and animals. The methods of the invention can also be used to regulate the expression of one or more non-coding KNA sequences in a transgenic cell or a transgenic animal by heritable transgene expression of mterfering KNA. These non-coding KNA. sequences can be sequences of an KNA virus genome, an endogenous gene, a eukaryotic parasite gene, or other non-coding KNA sequences fliat are known in the art and that will be familiar to the ordinarily skilled artisan. JRNA molecules teat are expressed in cells or animals according to the aspects of the present invention can decrease, increase or maintain expression of one ox more target genes, hi Older to identify specific target nucleic acid regions in which the expression of one or more genes, family of genes, desired subset of genes, or alleles of a gene is to be regulated, a representative sample of sequences for each target gene can be obtained. Sequences can be compared to find similar and dissimilar regions. This analysis can determine regions of identity between all family members and within subsets (i.e. groups within the gene family) of family members. In addition, this analysis can determines region of identity between alleles of each family member. By considering regions of identity between alleles of family members, between subsets of family members, and across the entire family, target regions can be identified that specify the entire family, subsets of family members, individual family members, subsets of alleles of individual family members, or individual alleles of family members.

Regulation of expression can decrease expression of one or more target genes. Decreased expression results in post-transcriptional down-regulation of the target gene and ultimately the final product protein of the target gene. For down-regulation, the target nucleic acid sequences are identified such, that binding of the iKNA to the sequence will decrease expression of the target gene. Decreased expression of a gene refers to the absence of or observable or detectable decrease in, the level of protein and/or mRNA product from a target gene relative to that without the introduction of the 2RNA. Complete suppression/inhibitioh as well as partial suppressed expression of the target gene are possible with the methods of the present invention. By "partial suppressed expression," it is meant that the target gene is suppressed (i.e. the expression of the target gene is reduced) from about 10% to about 99%, with 100% being complete suppression/ihhibition of the target gene. For example, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, or about 99% of gene expression of the one or more genes can be suppressed. Alternatively, expression is suppressed or inhibited below detectable threshold limits.

In other embodiments of the invention, regulation of expression can increase expression of one or more genes. Increased expression can result when the interfering ENA targets a nucleic acid sequence that acts as a suppressor of one or more genes of interest. In this embodiment of the invention, the target nucleic acid and the gene of interest can he separate sequences. Increased expression of a gene refers to the presence, or observable increase, in tire level of protein and/or mRNA product from one or more target genes relative to that without the introduction of the iKNA. By increased expression of a gene, it is meant that the measurable amount of the target gene that is expressed is increased any amount relative to that without the introduction of the iRNA. For example, the level of expression of the gene can be increased about two-fold, about five-fold, about 10-fold, about 50-fold, about 100-fold, about 500-fold, about 1000-fold, or about 2000-fold, above that which occurs in the absence of the interfering RNA.

In still other aspects of tire invention, regulation of expression can maintain expression of one or more genes, when the one or more genes are placed under environmental conditions that generally lead to increased or decreased expression of the one or more genes. Expression of one or more genes can be maintained under environmental conditions that would normally increase or decrease gene expression results in a steady-state level (i.e. no increase or decrease in expression with time) of gene expression relative to expression prior to the presence of environmental conditions that would otherwise increase or decrease expression. Examples of environmental conditions that can increase gene expression include, but are not limited to, the presence of growth factors, increased glucose production, hyperthermia and cell cycle changes. Examples of environmental conditions that can decrease gene expression include, tut axe not limited to, hypoxia, hypothermia, lack of growth factors and glucose depletion.

Quantitation of gene expression can allow one to determine the degree of inhibition (or enhancement) of gene expression in a cell or animal that contain one or more iRNA molecules. Lower doses of injected material and longer times after administration or integration of the iRNA can result in inhibition or enhancement in a smaller fraction of cells ox animals (e.g., at least 10%, 20%, 50%, 75%, 90%, or 95% of targeted cells or animals). Quantitation of gene expression in a cell or animal can show similar amounts of inhibition or enhancement at the level of accumulation of target xnRNA or translation of target protein. The efficiency of inhibition or enhancement can be determined by assessing the amount of gene product in the cell or animal using any method known in the art. For example, mRNA can be detected with, a hybridization probe having a nucleotide sequence outside the region used for the interfering RNA, or translated polypeptide can be detected with an antibody raised against the polypeptide sequence of that region. Methods by which to quantitate mRNA and polypeptides are well-known in the art see, for example, Sambrook, J. et al. "Molecular Cloning: A Laboratory Manual,” 2nd addition, Cold Spring Harbor Laboratory Press, Plainview, New York (1989).

The present invention also relates to the regulation of expression of a family of genes. The tern "family of genes” refers to one or more genes that have a similar function, sequence, or phenotype. A family of genes can contain a conserved sequence, i.e. a nucleotide sequence that is the same or highly homologous among all members of the gene family. In certain embodiments, the iRNA sequence can hybridize to this conserved region of a gene family, and thus one iRNA sequence can target more than one member of a gene family.

In one embodiment, the target gene or family of genes are genes of an endogeous virus, for example, porcine endogenous retrovirus. In another embodiment of the invention, the target genes or gene family are genes of an exogenous virus. Examples of exogenous viruses include, but are not limited to, zoonotic viruses (such as West Nile Virus, Hantavirus, Herpesvirus, Parvovirus, Enterovirus, Rabies, Filoviiuses, Human Immunodeficiency Virus, Influenza, and Napah Virus), livestock viruses (such as Rinderpest virus, foot and mouth disease virus, and Marek's disease vims), synthetic viruses and endemic viruses. Any viral gene that is not heritable as an integral element of 1he genome (chromosomal or extrachromosmal) of the species can be considered an exogenous virus and can be regulated by the methods of the invention. In one such embodiment, tire family of one or more genes of an. exogenous virus that axe regulated can be a family of related viral genes. Examples of related viral genes include, but are not limited to, gag genes, env genes and pol genes, which are related aB a family of retroviral genes.

The methods of the present invention can also be used to regulate expression of genes within an evolutionarily related family of genes. Evohitionarily related genes are genes that have diverged from a common progenitor genetic sequence, which can or can not have itself been a sequence encoding for one or more mKNAs. Within this evolutionarily related family can exist a subset of genes, and within this subset, a conserved nucleotide sequence can exist The present invention also provides methods by which to regulate expression of this subset of genes by targeting the iKNA molecules to this conserved nucleotide sequence. Evolutionarily related genes that can be regulated by the methods of 1he present invention can be endogenous or exogenous to a cell or an animal and can be members of a viral family of genes, in addition, the family of viral genes that can be regulated by the methods of the present invention can have family members that are endogenous to the cell or animal, M another embodiment of the invention, the methods of the invention can be used to regulate the life-cycle of a virus. In one such aspect of the invention, this regulation can result in the truncation, or shortening, of the life-cycle of a virus. By truncation or shortening of the life-cycle, it is meant that the virus survives for a shorter period of time than an identical virus that has not been regulated. A shorter period of time encompasses any amount of time that is less than, the life-cycle of an identical virus that has not been regulated. For example, the virus can survive for an amount of time that is about 1%, about 5%, about 10%, about 33%, about 50%, about 67%, about 75%, about 80%, about 85%, about 90%, about 95%, about 96%, about 97%, about 98%, about 99% or about 100% shorter than an identical virus that has not been regulated. A virus that is said to have its life-cycle truncated 100% represents a virus that does not survive for any amount of time after treatment of the virus, or a host cell harboring the vims, with an iKNA. in an alternative aspect, the iKNA induced regulation can result in the expansion, or lengthening of the life cycle of a virus. By expansion or lengthening of the life-cycle, it is meant that the virus survives for a longer period of time than an identical virus that has not been regulated. A longer period of time encompasses any amount of time that is greater than the life-cycle of an identical virus that has not been regulated. For example, the virus can survive for an amount of time that is about two-fold, about five-fold, about 10-fold, about fold, about 50-fold, about 70-fold, about 100-fold, about 500-fold, about 1000-fold, about 2000-times, etc., longer than an identical virus that has not bear regulated. la still other aspects of the invention, regulation, of expression can maintain the life cycle of a virus, when the virus is placed under environmental conditions that generally lead to expansion or truncation of its life-cycle. A life-cycle of a vims that is maintained under environmental conditions that would normally expand or truncate this life-cycle results in a steady-state (he. no expansion or truncation) life-cycle relative to a virus life-cycle in the presence of environmental conditions that would otherwise expand or truncate the life-cycle of the virus. Examples of environmental conditions that can expand the life-cycle of a virus include, but are not limited to, the presence of growth factors, increased glucose production, hyperthermia, cell cycle changes. Examples of environmental conditions that can truncate the life-cycle of a virus include, but are not limited to, hypoxia, hypothermia, lack of growth factors and glucose depletion.

Regulation of the life-cycle of a virus can result from regulation of an endogenous gene or family of endogenous genes that axe required for the life-cycle of the virus. The interfering RNA can also target a viral gene or family of viral genes, thereby regulating the life-cycle of the vims.

In other embodiments, the methods of the present invention can be used to regulate expression of genes, or family of genes, that are endogenous to a cell or animal. An endogenous gene is any gene that is heritable as an integral element of the genome of the animal species. Regulation of endogenous genes by methods of the invention can provide a method by which to suppress or enhance a phenotype or biological state of a cell or an animal. Examples of phenotypes or biological states that can be regulated include, but are not limited to, shedding or transmission of a virus, feed efficiency, growth rate, palalability, prolificacy, secondary sex characteristics, carcass yield, carcass fat content, wool quality, wool yield, disease resistance, post-partum survival and fertility. Additional endogenous genes that can also be regulated by the methods of the invention include, but are not limited to, endogenous genes that are required for cell survival, endogenous genes that are required for cell replication, endogenous genes that are required for viral replication, endogenous genes that encode an immunoglobulin, locus, and endogenous genes that encode a cell surface protein. Further examples of endogenous genes include developmental genes (e. g., adhesion molecules, cyclin kinase inhibitors, Writ .family members, Pax family members, Winged helix family members, Hox family members, cytokines/lymphokmes and their receptors, growth/differentiation factors and their receptors, neurotransmitters and their receptors), tumor suppressor genes (e.g., APC, BRCA1, BRCA2, MADH4, MCC, NF 1, NF2, RB 1, TP53, and WTI) and enzymes (e.g., ACC synthases and oxidases, ACP desaturases and hydroxylases, ADP-ghicose pyrophorylases, ATPases, alcohol dehydrogenases, amylases, amyloglucosidases, catalases, ceUulases, chalcone synthases, chitboases, cyclooxygenases, decarboxylases, dextrfnases, DNA and RNA polymerases, galactosidases, glucanases, glucose oxidases, granule-bound starch synthases, GTPases, helicases, heraicellulases, inlegrases, irmlinases, invertases, isomerases, kinases, lactases, lipases, lipoxygenases, lysozymes, nopaline synthases, octopine synthases, peetinesterases, peroxidases, phosphatases, phospholipases, phosphorylases, phytases, plant growth regulator synthases, polygalacturonases, proteinases and peptidases, pullanases, recombinases, reverse transcriptases, RUBISCOs, topoisomearases, and xylanases). hi one embodiment of the invention, the regulated genes, or family of genes, are genes of an integrated endogenous virus. Examples of integrated endogenous virus genes include, but are not limited to: porcine endogenous retrovirus (PERV) genes, oncogenes (e. g., ABU BCLI, BCL2, BCL6, CBFA2, CBL, CSFIR, ERBA, ERBB, EBRB2, ETSI, ETS1, ETV6, FGR, FOS, FYN, HCR, HRAS, JUN, KRAS, LCK, LYN, MDM2, MLL, MYB, MYC, MYCLI, MYCN, KRAS, PM 1, PML, RET, SRC, TALI, TCL3, and YES), growth factor receptor genes, B virus genes, and Simian T Lymphotrophic virus genes. Any viral gene that is inherited as an element of the genome of a species can be considered an endogenous viral gene and can be regulated by the methods of the invention. In one embodiment, tire family of one or more genes that is regulated can be a family of related viral genes.

The methods of the present invention can also be used to regulate the expression of a specific allele. Alleles are polymorphic variants of a gene that occupy the same chromosomal locus. The methods of the present invention allow for regulation of one or more specific alleles of a gens or a family of genes. In this embodiment, the sequence of the iRHA can be prepared such that one or more particular alleles of a gene ox a family of genes are regulated, while other additional alleles of the same gene or family of genes are not regulated.

In another embodiment of the invention, the regulated gene or family of genes is a gene of a eukaryotic parasite. Examples of eukaryotic parasites include, but are not limited to, helminths, protozoa and arthropods.

In farther embodiment, the methods of the present invention allow for the regulation of expression of non-coding KNA sequences. Non-coding RNA sequences are sequences that do not transcribe active proteins. These non-coding KNA sequences can be sequences of an endogenous or exogenous viral genome, they can he endogenous to the cell or animal, or they can also be sequences of a eukaryotic parasite.

In forther embodiments, the methods of the present invention allow for enrichment of homologous recombination events. If the siKNA transgene is located "outside" of die homologous targeting aims, then the siKNA transgeae is not retained in die genome of the cell in which recombination has occurred. However, if the the targeting vector integrates at a random location and therefore does not represent a homologous recombination event, the siKNA transgene will be present in the genome of such cells. When the siKNA transgene targets either a required gene, a gene that produces a selectable phenotype, or the selectable marker contained in the original targeting vector, then random integrations can be differentiated from targeting events. In this case, one can enrich for targeting events in relation to non-targeting integration events.

A. PERV hi one exemplary embodiment of the invention, the regulated genes, or family of genes, are genes of an integrated endogenous virus. A prototype of an endogenous virus is PERV (porcine endogenous retrovirus).

Jh an exemplary embodiment of the present invention, porcine endogenous retrovirus (PERV) genes can be regulated by the expression of at least two iRNA molecules such that trie expression of the PERV virus is functionally eliminated or below detection levels. PERV refers to a family of retrovirus of which three main classes have been identified to date: PERV-A (Genbank Accession No. AFQ38601), PERV-B (EMBL Accession No. PERY17013) and PERV-C (Genbank Accession No. AF038600) (Patience et al 1997, Alriyosbi et al 1998). The gag and pal genes of PERV-A B, and C are highly homologous, it is the env gene that differs significantly between the different types of PERV (eg., PERV-A PERV-B, PERV-Q. PERV-D has also recently been identified (see, for example, U.S. Patent No 6,261,806).

In one embodiment, iRNA directed to the PERV virus can decrease the expression of PERV by at least about 70%, 75%,80%, 85%, 90%, 95%, 97% or 99%, or alternatively, below detectable levels. To achieve this goal, the present invention provides at least two iRNA molecules that target the same sequence within the gag, pol or env region of the PERV genome. Further, al least two iRNA molecules are provided that target different sequences within the gag, pol or env regions of the PERV genome. Stall further, at least two iRNA molecules are provided that each target different regions (i.e. either gag, pol or env) of the PBRV genome. Additionally, multiple iRNA molecules are provided that combine these different targeting strategies, for example: at least two SNA. interference molecules directed to file gag region of PERV; at least two ΚΝΓΑ interference molecules directed to the pol region of PERV; and at least two RNA interference molecules directed to the env region of PERV are provided to target the PERV gene.

The present invention also provides porcine animals, as well as cells, tissues and organs isolated from non-human transgenic animals in which the expression of PERV is decreased or functionally eliminated via the expression of at least two iRNA molecules. In certain such embodiments, they are obtained from transgenic pigs that express one or more interfering RNAs that interfere with the porcine endogenous retrovirus gene, a family member of the porcine endogenous retrovirus gene or a member of a subset of the porcine endogenous retrovirus gene family.

With the recent success in pig cloning (Polejaeva et al, 2000; OnisM et al, 2000) and the knockout of al,3-galactosyltransferase (al,3GT) gene in pigs (Dai et al, 2002; Lai et al, 2002 ), xenotransplantation, is closer to becoming reality. The complete removal of the al,3gal epitope, the major xeno antigen, from pig organs and tissues should significantly reduce hyperacute rejection of pig xenografts. One potential risk for pig to human xenotransplantation is the potential for human infection with porcine endogenous retroviruses (PERVs). PERVs are type-C family retrovirus, ubiquitously found in all pig cells, tissues or organs. PERVs are an integral part of the pig genome with as many as 50 copies of PERV pro viruses per cell (Le Tissier et al, 1997). Most of the proviruses are defective, and only very few of them ate replication-coxapetent (Herring et al, 2001). At least three distinct PERV sequences have been identified (PERV-A, -B and-C), which are classed according to relative homologies within three different env gene subfamilies (Takeuchi Y et al, 1998; Blusch 2002). Perv-A and PERV-B show 92% amino-add identity to one another and 63-66% identity to gibbon ape leukemia virus, feline leukemia vims and Friend murine leukemia virus. Replication-competent PERV-A and PERV-B have been detected from PK-15 (porcine kidney-derived) cells, activated peripheral blood mononuclear cells (PBMCs), pig pancreatic islets and porcine aortic endothelial cells (Martin et al, 1998; Takeuchi et al, 1998; Wilson et al, 1998). Both PERV-A and PERV-B are able to infect human and porcine cells, while PERV-C, an ecotropic retrovirus, has not been shown to be able to infect normal human cells. Infection and pseudotyping experiments have demonstrated that PERV -A, -B and -C use different cell receptors. Studies of humans treated with living pig organs, tissues or cells have not found any evidence of PERV infection so far (Heneine 1998; Paradis 1999; Patience 1998)- However, in these studies, only human. PBMC cells were screened and most of the patients were not under immunosuppression. In die xenograft setting, organs or cells from pigs may be exposed directly to the bloodstream of the patient, and because these patients are usually iromunosuppressed, die risk of PERV infection may be enhanced. In addition, with, the development of al,3Gal negative pigs, another natural defense against viruses, such as PERV, may be suppressed. Normally, pre-foimed high-titer antibodies against alpha gal, present in all humans, would act as a first line of defense against viruses whose envelope is decorated with a-gal epitopes. However, if endogenous pro viruses arise from al,3Gal negative pigs, they will also lack α-gal, and thus could avoid this primary immune defense. As such, the potential exists that PERVs from al,3Gal negative pigs may have a greater chance to infect the patient.

Current strategies to reduce transmission of porcine endogenous retrovirus (PERV) involve reduction of PERV copy number by traditional breeding. Since PERV copy number and integration sites vary between pigs it is possible that one could use selective breeding to reduce the number of PERVs in the pig genome. This strategy is not only impractical from the point of view of required time, but also assumes that PERVs are transmitted exclusively by Mendelian inheritance. Since type-C retroviruses can integrate to form new pro-viruses, this assumption, is false (Mang, et al, 2001). A similar strategy is to screen large numbers of individual pigs and breeds of pigs in the hope of finding a genetic background that has a low number of PERVs and/or primarily defective PERVs. Again, assumptions are made that PERV numbers and integration sites are stable. In addition, an artificial comfort is created because such pigs would have been selected for few functional or human-tropic PERVs. However, most human-transmissible PERVs that have been characterized result from novel mRNA recombinations to generate new PERVs that were not in tire original genome (Oldmixm et al, 2002).

Id one aspect of the invention, a family of PERV genes can be regulated. Related PERV viruses include, for example PERV A, PERV B, PERV C, and PERV D. Examples of related PBRV genes include, but are not limited to, gag genes, env genes and pol genes.

Representative gag sequences can be found with the following Genbarik accession numbers: AF038599, AP038600, AF147808, API63266, AP417210, AF4I7211, AP417212, AF417213, AF417214, AF417215, AF417216, AF417217, AF417218, AF417219, AF417220, AF417221, AF435967, AW231947, AW308385 , AW358862, AY056035, AY099323, AY099324, AY26581I, BF441465, BF441466, BF441468, BF441469, BF443400, BI181099, ΒΠ83356, BI186129, BI398794, BB99234, CB468878, CB468924, CB479915 or EMBL; AJ133816, AJ133817, AJ133818, AJ279056, AJ279057, AJ293656, AJ293657, Y17013. Representative pol sequences can be found, with the foEcwing Genbank accession numbers: AF000572, AF033259, AF033260, AF038599, AF038600, AF147808, AF163265, AF163268, AF274705, AF402661, AF402662, AF402663, AF435966 , AF435967 , AF51I088, AF511Q89, AF511090, AF511091, AF511092, AF511093, AF511094, AF511095, AF511096, AF511097, AF511098, AF511099, AW416859, AW435835, AW447645, AY056Q35, AY099323, AY099324, BE013835, BF709087, BF709087 , ΒΙΠ9493, ΒΪ183551, BI183551 , BB04652, BB36152, CB287225, CF178916, CF178929, CF180285, CF18Q296, CF181622, CF181673, CF360188, CF360268, U77599, U77600 or EMBL; AJ005399, AJ005400, AJ005401, AJ005402, AJ005403, AJ005404, AJ0Q5405, AJ0Q5406, AJ00S407, AJ005408, AJ005409, AJ005410, AJ005411, AJ005412, AJ133816, AJ133817, AJ133818, AJ279056, AJ279057, AJ293656, AJ293657, Y12238, Y12239, Y17013, Y18744, Y18745, Y18746, Y18747, Y18748, Y18749, X99933.

Representative env-A sequences can be found with foe following Genbank accession numbers: AF130444, AF163264, AF163267, AF163269, AF296168, AF318386, AF318387, AF318389, AF417222, AF417223, AF417224, AF417225, AF417226, AF417230, AF417231, AF417232, AF426917, AF426918, AF426919, AF426920, AF426921, AF426922, AF426923, AF426924, AP426925, AF426926, AF426927, AF426928, AF426929, AF426930, AF426931, AF426934, AF426941, AF426942, AF426943, AF426944, AF426945, AF507940, BI119493, BI185465, BI185535, BB04699, BI336152, CB287431, CF178929 or EMBL; AJ288584, AJ288585, Y12238.

Representative env~B sequences can be found with foe following Genbank accession numbers: AF014162, AF426916, AF426932, AF426933, AF426935, AF426936, AF426937, AF426938, AF426939, AF426940, AF426946, AW657531, AY056Q24, AY056025, AY056026, AY056027, AY056028, AY056029, AY056030, AY056031, AY056032, AY056033, AY056034, ΒΙΠ8348, BI244560, CF180296, CF181717 or BMBL; AJ288586, AJ288587, AJ288588, AJ288589, AJ288590, AJ288591, AJ288592, Y12239.

Representative env-C sequences can be found with foe following Genbank accession numbers: AF318383, AF318384, AF318385, AF318388, AF402660, AF417227, AF417228, AF417229, BB36316, BM190587.

Representative env-D sequences can be found with foe following Genbank accession numbers: AF402661, AF402662, AF402663 or in US patent number 6,261,806.

Bx one embodiment, the PERV-A, PERV-B, and PERY-C family of genes can be targeted simultaneously by at least two iKNA molecules, hi another embodiment, the vims is a subset of a porcine endogenous retrovirus femily.

In. another, the cells, tissues and organs of pigs that contain iKNA molecules that regulate PERV can he used for xenotransplantation.

Cell Types

The constructs, templates and vectors described herein can he introduced into host cells via any technique known in the art, including but not limited to microinjectioiL, transfection, transformaticm, and/or electroporation. Ihe host cell can be any mammalian, plant, yeast or bacterial cell. In one embodiment, the host cell is a prokaryote, such as a bacterid cell including, but not limited to an Escherichia or a Pseudnrpnnas species. In another embodiment the host cell is a eukaryotic cell, for example an insect cell, including but not limited to a ceE from a Spodoptera, IHchoplusia, Drosophila or an Estigmene species, or a mammalian cell, including but not limited to a human cell, murine cell, a porcine cell, a bovine cell, an ovine cell, a rodent cell, a hamster cell, a monkey, a primate or a human cell. The mammalian cell can be a cell obtained from a variety of different organs and tissues such as, but not limited to, skin, mesenchyme, lung, pancreas, heart, intestine, stomach, bladder, blood vessels, kidney, urethra, reproductive organs, and a disaggregated preparation of a whole or part of an embryo, fetus or adult animal; or epithelial cells, fibroblast cells, neural cells, keratinocytes, hematopoietic cells, melanocytes, chondrocytes, lymphocytes (B and T), macrophages, monocytes, mononuclear cells, cadiac muscle cells, other muscle cells, grandiose cells, cumulus cells, epidermal cells or endothelial cells. The host cells can he HEK cells, COS cells, or other cell commonly used in cell culture. In another embodiment, the host cell is a plant cell, including, but not limited to, a tobacco cell, com, a cell from an Arabidopsis species, potato or rice cell. V. Production of Genetically Modified Animals

The present invention also includes methods of producing non-human transgenic animals which heritably express one or more interfering RNAs. Any non-human transgenic animal can be produced by any one of ihe methods of the present invention including, but not limited to, non-human mammals (including, but not limited to, pigs, sheep, goats, cows (bovine), deer, mules, horses, monkeys and other non-human primates, dogs, cats, rats, mice, rabbits), birds (including, but not limited to chickens, turkeys, ducks, geese and the like) reptiles, fish, amphibians, worms (e.g. C. elegans), insects (including but not limited to, Drosophila, Trichoplusa, and Spodoptera).

The present invention also provides a non-human transgenic animal that has at least two ίΚΝΑ sequences inserted in its genome. In one embodiment, the animal is capable of expressing the iRNA molecule within the majority of its cells. In another embodiment, the animal is capable of expressing file iRNA molecule in virtually all of its cells. Since the sequence is incorporated into the genome of the animal, the iRNA molecules will be inherited by subsequent generations, thus allowing these generations to also produce the iRNA within their cells.

In one aspect of the present invention, non-human transgenic animals are produced via the process of nuclear transfer. In an alternate aspect, the present invention provides methods of producing a non-human transgenic animal through the genetic modification of totipotent embryeme cells.

Nuclear Transfer/ Cloning

In one embodiment of the present invention, non-human transgenic animals are produced via the process of nuclear transfer. In one embodiment, the nuclear donor cells can be genetically modified by the targeting constructs described herein to produce iRNA molecules. Production of non-human transgenic animals which express one or more interfering KNAs via nuclear transfer comprises: (a) identifying one or more target nucleic acid sequences in an animal; (b) preparing one or more interfering KNAs, wherein the interfering KNAs bind to the target nucleic acid sequences; (c) preparing one or more expression vectors containing the one or more interfering RNAs; (d) inserting the one or more interfering RNA expression vectors into the genome of a nuclear donor cell; (e) transferring the genetic material of the nuclear donor cell to an acceptor cell; (f) transferring the acceptor cell to a recipient female animal; and (g) allowing the transferred acceptor cell to develop to term in the female animal. Any animal can be produced by nuclear transfer, including, but not limited to: porcine, bovine, ovine, equine, and rodents, including mice and rats, rabbits.

Nuclear transfer techniques or nuclear transplantation techniques are known in file art (Campbell et at, Theriogenology, 43:181 (1995); Collas, et cd, Mol. Report Dev., 38:264-267 (1994); Keefer et al, Biol. Reprod., 50:935-939 (1994); Sims, et al, Proc. Nail. Acad. Sci„ USA, 90:6143-6147 (1993); WO 94*26884; WO 94/24274, and WO 90/03432, U.S. Pat Nos. 4,944,384 and 5,057,420). In cue τι limiting example methods acre provided such as those described in U.S. Patent Publication No. 2003/0046722 to Collas, et al., which describes methods for cloning mammals that allow the donor chromosomes or donor cells to be reprogrammed prior to insertion into an enucleated oocyte. The invention also describes methods of inserting or fusing chromosomes, nuclei or cells with oocytes. A donor cell nucleus, can be transferred to a recipient porcine oocyte. The use of this method is not restricted to a particular donor cell type. Hie donor cell can be as described in Wihnut, et al, Nature 385 810 (1997); Campbell, et al., Nature 380 64-66 (1996); or Cibelli, et al., Science 280 1256-1258 (1998). AH cells of normal karyotype, including embryonic, fetal and adult somatic cells which can be used successfully in nuclear transfer can in principle be employed. Fetal fibroblasts are a particularly useful class of donor cells. Generally suitable methods of nuclear transfer are described in Campbell, et al., Theriogenology 43 181 (1995), Collas, ei al, Mol. Reprod. Dev. 38 264-267 (1994), Keefer, et al, Biol Reprod. SO 935-939 (1994), Sims, et al, Proc. Natl Acad. Sci. USA 90 6143-6147 (1993), WO-A-9426884, WO-A-9424274, WO-A-9807841, WO-A-9003432, U-S. Pat No. 4,994,384 and U.S. Pat. No. 5,057,420. Differentiated or at least partially differentiated donor cells can also be used. Donor cells can also be, but do not have to be, in culture and can be quiescent. Nuclear donor cells which are quiescent are cells which can be induced to enter quiescence or exist in a quiescent state in vivo. Prior art methods have also used embryonic cell types in cloning procedures (Campbell, et al (.Nature, 380:64-68, 1996) and Slice, et al (Biol Reprod., 20 54:100-110,1996).

Somatic nuclear donor cells may be obtained from a variety of different organs and tissues such as, but not limited to, skin, mesenchyme, lung, pancreas, heart, intestine, stomach, bladder, blood vessels, kidney, urethra, reproductive organs, and a disaggregated preparation of a whole or part of an embryo, fetus or adult animal. In a suitable embodiment of the invention, nuclear donor cells are selected from the group consisting of epithelial cells, fibroblast cells, neural cells, kerafinocytes, hematopoietic cells, melanocytes, chondrocytes, lymphocytes (B and Ί), macrophages, monocytes, mononuclear cells, cadiac muscle cells, other muscle cells, granulose cells, cumulus cells, epidermal cells or endothelial cells. In another embodiment, the nuclear cell is an embryonic stem cell, hi a preferred embodiment, fibroblast cells can be used as donor cells.

In another embodiment of the invention, the nuclear donor cells of the invention are germ cells of an animal. Any germ cell of an animal species in the embryonic, fetal, or adult stage maybe used as a nuclear donor cell. In a suitable embodiment, the nuclear donor cell is an embryonic germ cell.

Nuclear donor cells may be arrested in any phase of die cell cycle (GO, GI, G2, S, M). Any method known in the art may be used to manipulate the cell cycle phase. Methods to control the cell cycle phase include, but are not limited to, GO quiescence induced by contact inhibition of cultured cells, GO quiescence induced by removal of serum or other essential nutrient, GO quiescence induced by senescence* GO quiescence induced by addition of a specific growth factor; GO ox GI quiescence induced by physical or chemical means such as beat shock, hyperbaric pressure or other treatment with a chemical, hormone, growth factor or other substance; S-phase control via treatment -with a chemical agent which interferes with any. Point of the replication procedure; M-phase control via selection using fluorescence activated cell sorting, mitotic shake off, treatment with microtubule disrupting agents or any chemical which disrupts progression in mitosis (see also Freshney, R. 1,. “Culture of Animal Cells: A Manual of Basic Technique,” Alan R. Liss, Inc, New York (1983)).

Methods for isolation of oocytes are well known in the art. For example, oocytes can be isolated from the ovaries or reproductive tract of an animal. A readily available source of animal oocytes is slaughterhouse materials. For die combination of techniques such as genetic engineering, nuclear transfer and cloning, oocytes must generally be matured in vitro before these cells can be used as recipient cells for nuclear transfer, and before they can be fertilized by the sperm cell to develop into an embryo. This process generally requires collecting immature (prophase Γ) oocytes from mammalian ovaries, e.g., bovine oyaries obtained at a slaughterhouse, and maturing toe oocytes in a maturation medium prior to fertilization or enucleation until toe oocyte attains the metaphase Π stage, which in the case of bovine oocytes generally occurs about 18-24 hours post-aspiration. This period of time is known as toe “maturation period”. A metaphase Π stage oocyte can be the recipient oocyte, at this stage it is believed that toe oocyte can be or is sufficiently “activated” to treat the introduced nucleus as it does a fertilizing sperm. Metaphase II stage oocytes, which have been matured in vivo have been successfully used in nuclear transfer techniques. Essentially, mature metaphase H oocytes can be collected surgically from either non-sup erovulated or superovulated porcine 35 to 48, or 39-41, hours past toe onset of estrus or past toe injection of human chorionic gonadotropin (hCG) or similar hormone.

After a fixed time maturation period, which ranges from about 10 to 40 hours, and preferably about 16-18 hours, the oocytes can be enucleated. Prior to enucleation the oocytes can be removed and placed in appropriate medium, such as HECM containing 1 milligram per milliliter of hyahironidase prior to removal of cumulus cells. The stripped oocytes can then be screened far polar bodies, and the selected metaphase H oocytes, as determined by the presence of polar bodies, are then used for nuclear transfer. Enucleation follows.

Enucleation can be performed by known methods, such as described in U.S. Pat No. 4,994,384. For example, metaphase H oocytes can be placed in either HBCM, optionally containing 7.5 micrograins per milliliter cytochalasin B, for immediate enucleation, or can be placed in a suitable medium, for example an embryo culture medium such as CRlaa, plus 10% estras cow serum, and then enucleated later, preferably not more than 24 hours later, and more preferably 16-18 hours later. Enucleation can be accomplished nricrosurgically using a micropipette to remove the polar body and the adjacent cytoplasm. The oocytes can then be screened to identify those of which have been successfully enucleated One way to L.een the oocytes is to stain the oocytes with 1 microgram per milliliter 33342 Hoechst dye in HECM, and then view the oocytes under ultraviolet irradiation for less than 10 seconds. The oocytes that have been successfully enucleated can then be placed in a suitable culture medium, for example, CR1 aa plus 10% serum. A single mammalian cell of the same species as the enucleated oocyte can then be transferred into the periviteUine space of the enucleated oocyte used to produce foe NT umt The mammalian cell and foe enucleated oocyte can be used to produce NT units according to methods known in the art. For example, foe cells can be fused by electrofusion. Electrofusion is accomplished by providing a pulse of electricity that is sufficient to cause a transient breakdown of the plasma membrane. This breakdown of foe plasma membrane is very short because foe membrane reforms rapidly. Thus, if two adjacent membranes are induced to breakdown and upon reformation foe lipid bilayers intermingle, small channels can open between the two cells. Hue to foe thermodynamic instability of such a small opening, it enlarges until the two cells become one. See, for example, U.S. Pat No. 4,997,384 by Prather et al A variety of electrofusion media can be used including, for example, sucrose, mannitol, sorbitol and phosphate buffered solution. Fusion can also be accomplished using Sendai virus as a fusogenic agent (Graham, Wister InoL Symp. Monogr., 9, 19, 1969). Also, foe nucleus can he injected directly into foe oocyte rather than using electroporation fusion. See, for example, Collas and Barnes, Mol Reprod Dev., 38:264-267 (1994). After fusion, foe resultant fused NT units are then placed in a suitable medium until activation, for example, CRlaa medium. Typically activation can be effected shortly thereafter, for example less than 24 hours later, or about 4-9 hours later.

The NT unit can be activated by any method that accomplishes the desired result. Such methods include, for example, culturing the NT unit at sub-physiological temperature, in essence by applying a cold, or actually cool temperature shock to the NT unit. This can be most conveniently done by culturing the NT unit at room temperature, which is cold relative to the physiological temperature conditions to which embryos are normally exposed. Alternatively, activation can be achieved by application of known activation agents. For example, penetration of oocytes by spenn during fertilization, has been shown to activate prefiision oocytes to yield greater numbers of viable pregnancies and multiple genetically identical animals, such as pigs, after nuclear transfer. Also, treatments such as electrical and chemical shock can be used to activate NT embryos after fusion. See, for example, U.S. Pat. No. 5,496,720, to Susko-Parrish, ei al. Additionally, activation can be effected by simultaneously or sequentially by increasing levels of divalent cations in the oocyte, and reducing phosphorylation of cellular proteins in the oocyte. This can generally be effected by introducing divalent cations into the oocyte cytoplasm, e.g., magnesium, strontium, barium or calcium, e.g., in the form of an ionophore. Other methods of increasing divalent cation levels include fee use of electric shock, treatment with ethanol and treatment with caged chelators. Phosphorylation can be reduced by known methods, for example, by the addition of kinase inhibitors, e.g., serine-threonine kinase inhibitors, such as 6-dimethyl-aminopurine, staurosporine, 2-aminopurine, and sphingosine. Alternatively·, phosphorylation of cellular proteins can be inhibited by introduction of a phosphatase into the oocyte, e.g., phosphatase 2A and phosphatase 2B.

The activated NT units can then be cultured in a suitable in vitro culture medium until the generation of cell colonies. Culture media suitable for culturing and maturation of embryos are well known in the art. Examples of known media, which can be used for embryo culture and maintenance, include Ham’s F-1(H-10% fetal calf serum (FCS), Tissue Culture Medium-199 (TCM-199)+10% fetal calf serum, Tyrodes-Albumin-Lactate-Pymvate (TALP), Dulbecco’s Phosphate Buffered Saline (PBS), Eagle’s and Whitten’s media.

Afterward, the cultured NT unit or units can be washed and then placed in a suitable media contained in well plates which preferably contain a suitable confluent feeder layer. Suitable feeder layers include, by way of example, fibroblasts and epithelial cells. The NT units are cultured on fee feeder layer until fee NT units reach a size suitable for transferring to a recipient female, or for obtaining cells which can he used to produce cell colonies.

Preferably, these NT units can be cultured until at least about 2 to 400 cells, more preferably about 4 to 128 ceils, and most preferably at least about 50 cells.

Activated NT units can then be transferred (embryo transfers) to the oviduct of an female animals. In one embodiment, the female animals can "be an estrus-syncbronized recipient gilt Crossbred gilts (large wMte/Duroc/Landrace) (280-400 lbs) can be used. The gjlts can be synchronized as recipient animals by oral administration of 18-20 mg ReguMate (Altrenogest, Hoechst, Warren, NT) mixed into fee feed. Regu-Mate can be fed for 14 consecutive days. One thousand units of Human Chorionic Gonadotropin (hCG, Intervet America, Millsboro, DE) can then be administered im. about 105 h after fee last Regu-Mate treatment Embryo transfers of fee can then be performed about 22-26 h after the hCG injection. In one embodiment, fee pregnancy can be brought to term and result in the birth of live offspring. In another embodiment, fee pregriancy can be 5 terminated early and embryonic cells can be harvested.

The methods for embryo transfer and recipient animal management in the present invention are standard procedures used in the embryo transfer industry. Synchronous transfers are important for success of the present invention, Le., fee stage of the NT embryo is in synchrony wife fee estrus cycle of the recipient female. See, for example, Siedel, G. E., Jr. “Critical review of embryo transfer procedures with cattle” in Fertilization and Embryonic Development in Vitro (1981) L. Mastroianni, Jr. and J. D. Biggers, ed., Plenum Press, New York, N.Y., page 323.

Other Methods to Produce Genetically Modified Animals

In additional embodiments of fee present invention, transgenic animals can be produced by any means known in the art, including, but not limited to the following: microinjectioa of DNA into oocyte, zygotes or pre-implantation blastomeres (such as 2 cell, 4 cell or 8 cell blastomsrs), transfection of embryonic stem cells, sperm-mediated deliver of DNA and transfecting embryons in vivo via fee blood steam.

In one embodiment, fee present invention provides methods of producing a non-human transgenic animal that express at least two interfering RNAs through the genetic modification of totipotent embryonic cells, hr one embodiment, the animals can be produced by: (a) identifying one or more target nucleic acid sequences in an animal; (b) preparing one or more interfering RNAs, wherein the mterfermg RNAs bind to fee target nucleic acid sequences; (c) preparing one or more expression vectors containing the one or more interfering RNAs; (d) inserting fee one or more interfering RNA expression vectors into fee genomes of a plurality of totipotent cells of the animal species, thereby ptodncxag a plurality of transgenic totipotent cells; (e) obtaining a tetraploid blastocyst of the annual species; (f) inserting the plurality of totipotent cells into the tetraploid blastocyst, thereby producing a transgenic embryo; (g) transferring the embryo to a recipient female animal; and (h) allowing tite embryo to develop to term in the female animal. The method of transgenic animal production described here by which to generate a transgenic animal, such as a mouse, is further described in U.S. Patent No. 6,492,575. hi another embodiment, the totipotent cells can be embryonic stem (ES) cells. The isolation of ES cells from blastocysts, the establishing of ES cell lines and their subsequent cultivation are carried out by conventional methods as described, for example, by Doetchmaxm et al., J. Emhryol. Exp. Morph. 87:27-45 (1985); Li et al., Cell 69:915-926 (1992); Robertson, E. J. “Tetracarcinomas and Embryonic Stem Cells: A Practical Approach," ed. E. J. Robertson, IRL Press, Oxford, England (1987); Wurst and Joyner, "Gene Targeting: A Practical Approach," ed. A L. Joyner, ERL Press, Oxford, England (1993); Hogen et al., "Manipulating the Mouse Embryo: A Laboratory Manual," eds. Hogan, Beddmgton, Costantmi and Lacy, Cold Spring Harbor Laboratory Press, New York (1994); and Wang et al., Nature 336:741-744 (1992).

In a further embodiment of the invention, the totipotent ceils can be embryonic germ (EG) cells. Embryonic Germ cells are undifferentiated cells functionally equivalent to ES cells, that is they can be cultured and transfected in vitro, then contribute to somatic and gaum cell lineages of a chimera (Stewart et al., Dev. Biol. 161:626-628 (1994)). BG cells are derived by culture of primordial germ cells, the progenitors of the gametes, with a combination of growth factors: leukemia inhibitory factor, steel factor and basic fibroblast growth facto: (Maisui et al., Cell 70:841-847 (1992); Resnick et al., Nature 359:550-551 (1992)). The cultivation of EG cells can be carried out using methods known to one skilled in the art, such as described in Donovan et al., 'Transgenic Animals, Generation and Use," Ed L. M. Houdebine, Harwood Academic Publishers (1997).

Tetraploid blastocysts for use in the invention can be obtained by natural zygote production and development, or by known methods by electrofusion of two-cell embryos and subsequently cultured as described, for example, by James et al., Genet. Res. Camb. 60:185-194 (1992); Nagy and Rossant, "Gene Targeting: A Practical Approach," ed A. L. Joyner, IRL Press, Oxford, England (1993); or by Kubiak and Tarkowski, Exp. Cell Res. 157:561-566 (1985).

The introduction of the ES cells or EG cells into the blastocysts can be carried out by any method known in the art, for example, as described by Wang et al, EMBO J. 10:2437-2450(1991). A ’’plurality" of totipotent cells can encompass any number of cells greater than one. For example, the number of totipotent cells for use in the present invention cm be about 2 to about 30 cells, about 5 to about 20 cells, or about 5 to about 10 cells. In one embodiment, about 5-10 ES cells taken from a single cell suspension are injected into a blastocyst immobilized by a holding pipette in a nmcromampulation apparatus. Then the embryos are incubated for at least 3 hours, possibly overnight, prior to introduction into a female recipient animal via methods known in the art (see for example Robertson, E. J. 'Teratocarcitiomas and Embryonic Stem Cells: A Practical Approach” IRL Press, Oxford, England (1987)). The embryo can then be allowed to develop to term in the female animal.

In. one embodiment of the invention, the methods of producing transgenic animals, whether utilizing nuclear transfer, embryo generation, or other methods known in the art, result in a transgenic animal comprising a genome that does not contain significant fragments of the expression vector used to transfer the iRNA molecules. The term "significant fragment” of the expression vector as used herein denotes an amount of the expression -vector that comprises about 10% to about 100% of the total original nucleic acid sequence of the expression vector. This excludes the iRNA insert portion that was transferred to the genome of the transgenic animal. Therefore, for example, the genome of a transgenic animal that does NOT contain significant fragments of the expression vector used to transfer the iRNA, can contain no fragment of the expression vector, outside of the sequence that contains the iHNA. Similaxly, the genome of a transgenic animal that does not contain significant fragments of the expression vector used to transfer the iRNA can contain about 1%, about 2%, about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about 9%, or about 10% of the expression vector, outside of the sequence that contains the iRNA. Any method which allows transfer of the iRNA sequence to the genome while also limiting the amount of the expression vector that is also transferred to a fragment that is not significant can be used in toe methods of toe present invention.

One embodiment of the invention which allows transfer of the iRNA sequence to toe genome while also limiting toe amount of toe expression vector that is also transferred to a fragment that is not significant, is toe method of recombinational cloning, see, for example, U.S. Patent Nos. 5,888,732 and 6,277,608.

RecoEobinatioBal cloning (see, for example, U.S. Patent Nos. 5,888,732 and 6,277,608) describes methods for moving or exchanging nucleic add segments using at least one recombination site and at least one recombination, protein to provide chimeric DMA. molecules. One method of producing these chimeric molecules which is useful in the methods of the present invention to produce the iRNA expression vectors comprises: combining in vitro or in vivo, (a) one or more nucleic add molecules comprising the one or more iRNA sequences of the invention flanked by a first recombination site and a second recombination site, wherein, the first and second recombination sites do not substantially recombine with each other; (b) one or more expression vector molecules comprising a third recombination site and a fourth recombination site, wherein the third and fourth recombination sites do not substantially recombine with each other; and (c) one or more site specific recombination proteins capable of recombining the first and third recombinatiorial sites and/or the second and fourth reconabinational sites, thereby allowing recombination, to occur, so as to produce at least one cointegrate nucleic add molecule which comprises the one or more iRNA sequences.

Recombination sites and recombination proteins for use in tire methods of the present invention, include, but are not limited to those described in U.S. Patent Nos. 5,888,732 and 6,277,608, such as, Cre/loxP, hrtegrase (WEat, Xis, IHF and FIS)/att sites (attB, attP, attL and attR), and FLP/FRT. Members of a second family of site-specific recotribinases, the resolvase family (e.g., gd, Tn3 resolvase, Hm, Gin, and Cm) are also known and can be used in the methods of the present invetion. Members of this highly related family of recombinases axe typically constrained to intramolecular reactions (e.g., inversions and excisions) and can require host-encoded factors. Mutants have been isolated that relieve some of the requirements for host factors (Maeser and Kahmnann Mol. Gen. Genet 230:170-176 (1991)), as well as some of the constraints of intramolecular recombination.

Other site-specific recombinases similar to λ&amp;ϋ and similar to PI Cre that are known in the art and that will be familiar to one of ordinary skill can be substituted for Int and Cre. In many cases the purification of such other recombinases has been described in the art In cases when they are not known, cell extracts can he used or the enzymes can be partially purified using procedures described for Cre and Int.

The family of enzymes, the transposases, have also been used to transfer genetic information between replicons and can be used in the methods of the present invention to transfer iRNAs. Transposons are structurally variable, being described as simple or compound, but typically encode the recombinase gene flanked by DNA sequences organized 131 inverted orientations. Integration of transposons can be random or highly specific. Representatives such as Tn7, which are highly site-specific, have been applied to the in vivo movement of DNA segments between repHcons (Lucklow et ah, J. Virol. 67:4566-4579 (1993)). For example, Devine and Boeke (Nucl. Acids Res. 22:3765-3772 (1994)) disclose the construction of artificial transposons for the insertion of DNA segments, in vitro, into recipient DNA molecules. The system makes use of the integrase of yeast TY1 virus-like particles. The nucleic segment of interest is cloned, using standard methods, between the ends of the transposon-like element ΊΎ1. hi the presence of the ΤΎ1 integrase, the resulting element integrates randomly into a second target DNA molecule.

Additional recombination sites and recombination proteins, as well as mutants, variants and derivatives thereof, for example, as described in U.S. Patent Nos. 5,888,732, 6,277,608 and 6,143,557 can also be used in the methods of the present invention.

Following die production of an expression vector ctmtainmg one or more iRNAs flanked by recombination proteins, the iRNA nucleic add sequences can be transferred to the genome of a target cell via reconibinational cloning. In this embodiment, the recombination proteins flanking the iRNA are capable of recombining with one or more recombination proteins in the genome of the target cell, ha combination with one or more site specific recombination proteins capable of recombining the recombination sites, the iRNA sequence is transferred to the genome of the target cell without transferring a significant amount of the remaining expression vector to the genome of the target cell. The recombination sites in the genome of the target cedi can occur naturally or the recombination sites can be introduced into the genome by any method known in the art In either case, the recombination sites flanking the one or more iRNA sequences in the expression vector must be complementary to the recombination sites in the genome of the target cell to allow for ^combinational cloning.

Another embodiment of the invention relates to methods to produce a non-human transgenic or chimeric animal, comprising crossing a male and female non-human transgenic animal produced by any one of the methods of the invention to produce additional transgenic or chimeric animal offspring. By crossing transgenic male and female animals that both contain the one or more iRNAs in their genome, the progeny produced by this cross also contain the iRNA sequences in their genome. This crossing pattern can be repeated as many times as desired.

In another embodiment, a male or female non-human transgenic animal produced by the methods of the invention can be crossed with a female or male animal respectively, wherein the second female or male animal involved in the cross is not a non-human transgenic animal produced by die methods of die invention. Since iRNA is dominant in nature, the progeny from these crosses can also express the flRNA. sequences in this genomes. Crosses where at least one animal is a non-human transgenic animal of die present invention can result in progeny that possess the iRNA. sequences in their genomes, in another embodiment, semen from a male non-human transgenic animal produced by die methods of the invention can be used to impregnate female animals and produce progeny that contain the iRNA sequences in their genome. VL Therapeutic Uses and Pharamceuiical Compositions A. Therapeutic Uses

The non-human transgenic animals of the present invention can also be used as sources for therapeutic proteins expressed from transgan.es. ϊη one embodiment, the methods of the present invention can be used to reduce the amount of one or more endogenous proteins expressed by an animat. The transgene expression can be targeted to specific tissues or cells types to provide compartmentalized isolation of such proteins. For example, a protein can be concentrated in milk of a transgenic animal by driving expression of the protein from a mammary specific promoter. In addition, a transgene can be selectively expressed in a specific cell type to allow for specific processing. For example, a human immunoglobulin locus can be used to direct recombination, expression, and processing of human polyclonal antibodies in livestock 6-cells. One of the current problems with utilizing transgenic animals as sources of therapeutic proteins is that proteins endogenous to the animal can contaminate the material collected (i.e. peptides, proteins and nucleic adds) for purification and ultimate use in a therapeutic setting. While contaminating proteins can be cvolutionarily unrelated, they can co-purify with the desired product Alternatively, the contaminating protein can be the endogenous counterpart of the transgene product. In either case, a reduction in expression of the endogenous gene or genes is beneficial from both an economic and therapeutic standpoint One embodiment of the methods of the invention is the reduction of endogenous immunoglobulin genes to allow production of non-chimeric, non-contaminated human polyclonal antibodies in transgenic animals.

In another aspect, the present invention provides iRNA-mediated gene regulation in non-human transgenic animals viaknockout/inhibition of the entire repertoire of endogenous immunoglobulin (Ig) gene loci, and replacement of the animal Ig genes with their human equivalents. The genetically modified animals produced using this strategy are thus be able to produce fully human antibodies, in both, their blood and in milk, when challenged with a specific pathogen or immunogen. There are numerous applications for this technology in the general healthcare arena including: infectious disease prophylaxis, treatment of antibiotic-resistant infections, passive immunization in immunocompromised patients, for immune globulin in post-transplant viral pipphylaxsis against hepatitis and CMV, HIV therapy, immunization against Hepatitis C, anti-venoms, as a polyclonal anti-cancer agent, cancer diagnostics, treatment of autoimmune diseases (Multiple Sclerosis, Kawasaki’s), and production of anti-D for Rh negative mothers.

In addition, non-human transgenic animals producing human polyclonal antibodies have important applications in biowarfare countermeasures, whereby the animals are immunized with any of the known infectious disease pathogens, or their products, and produce specific human antibodies (preferably IgG), for use as a therapeutic, or for passive immunization of Armed Forces personnel. The use of human polyclonal antibodies derived from animals is broad-spectrum, and not limited to one or a few pathogenic organisms. Any immunogen could be used to immunize these animals, to induce the production of antibodies for prophylaxsis from, a variety of pathogenic organisms including, but not limited to, anthrax, staphylococcus, gram negative bacteria, Ebola virus, and Hanta virus. Additional immunogen include, but are not limited to, venoms, and bacterial toxins. The production of human antibodies in animals has the advantage of scale, given that depending on whether they were isolated from blood or milk, one could obtain 2-5 kilograms of specific antibody per animal (especially when considering the use of porcine, ovine or bovine) per year, such that a small number of animals could easily supply the needs of thousands of patients. Antibodies to many of these organisms are currently unavailable in any significant quantity due to their rarity in the general developed population, and because they cannot be used as immunogens in any form in humans due to their virdence/toxicity. Also, because these antibodies are fully human, they are far superior in specificity, avidity, and potency to antiserums currently being produced in horses and goats. Precedence far this application has been achieved in mice, using mouse ES cell technology. Mendez et.al, (Nature Genet. 15:146-156, (1997)) demonstrated functional transplantation of megabase human immunoglobulin loci into Ig-deficient knockout mice, and observed human antibody production in these mice that closely resembled that seat in humans.

In one embodiment, the methods of the present invention provides for production of human polyclonal antibodies in transgenic cattle, sheep and pigs. Cattle can be produced that expressed human irmnunogdobutins, these bovine however have limited utility because of antibody cbwnerism and contamination of endogenous antibodies. A method to render the bovine genes inactive is highly desirable from the point of view of both production and purification. The application of RNA interference via the methods of tire present invention allows one to inactivate/suppress the highly repetitive livestock % genes with relatively few inhibitory RNAs, and without the requirement of having to clone out large pieces of uncharacterized genomic DNA. Cloned animals feat expressed human Ig genes, in the absence of livestock Igs, produce human polyclonal antibodies that are then easily purified without the issues of contamination from the endogenous animal Igs. Methods to purify antibodies isolated from the non-human transgenic animals of the present invention are known in the art (see for example Sambrook, J. et ah "Molecular Cloning: A Laboratory Manual", 2nd addition, Cold Spring Harbor Laboratory Press, Plainview, New York (1989)).

In one embodiment, the invention provides organs, tissues and/or purified or substantially pure cells or cel lines obtained from animals that express iKNA molecules. hr one embodiment, the invention provides organs, any organ can be used, including, but not limited to: brain, heart, lungs, glands, brain, eye, stomach, spleen, panaceas, kidneys, liver, intestines, uterus, bladder, skin, hair, nails, ears, nose, mouth, Kps, gums, teeth, tongue, salivary glands, tonsils, pharynx, esophagus, large intestine, small intestine, rectum, anus, pylorus, thyroid gland, thymus gland, suprarenal capsule, bones, cartilage, tendons, ligaments, skeletal muscles, smooth muscles, blood vessels, blood, spinal cord, trachea, ureters, urethra, hypothalamus, pituitary, adrenal glands, ovaries, oviducts, uterus, vagina, mammary glands, testes, seminal vesicles, penis, lymph, lymph nodes and lymph vessels.

In another embodiment, the invention provides tissues. Any tissue can be used, including, but not limited to: epithelium, connective tissue, blood, bone, cartilage, muscle, nerve, adenoid, adipose, areolar, bone, brown adipose, cancellous, muscle, cartaginous, cavernous, chondroid, chromaffin, dartoic, elastic, epithelial, fatty, fibrohyaliae, fibrous, Gamgee, gelatinous, granulation, gut-associated lymphoid, Haller’s vascular, hard hemopoietic, indifferent, interstitial, investing, islet, lymphatic, lymphoid, mesenchymal, mesonephric, mucous connective, multilocular adipose, myeloid, nasion soft, nephrogenic, nodal, osseous, osteogenic, osteoid, periapical, reticular, retiform, rubber, skeletal muscle, smooth muscle, and subcutaneous tissue.

In a further embodiment, the invention provides cells and cell lines from animals that express iKNA molecules, fir one embodiment, these cells or cell lines can be used for xenotransplantation. Cells from any tissue or organ can be used, including, but not limited to: epithelial cells, fibroblast cells, neural cells, keratinocytes, hematopoietic cells, melanocytes, chondrocytes, lymphocytes (B and T), macrophages, monocytes, mononuclear cells, cardiac muscle cells, other muscle cells, granulosa cells, cumulus cells, epidermal cells, endothelial cells, Islets of Langerhans cells, pancreatic insulin secreting cells, pancreatic alpha-2 cells, pancreatic beta cells, pancreatic alpha-1 cells, blood cells, blood precursor cells, bone cells, bone precursor cells, neuronal stem, cells, primordial stem cells., hepatocytes, keratinocytes, umbilical vein endothelial cells, aortic endothelial cells, microvascular endothelial cells, fibroblasts, liver stellate cells, aortic smooth muscle cells, cardiac myocytes, neurons, Kupffer cells, smooth muscle cells, Schwann cells, and epithelial cells, erythrocytes, platelets, neutrophils, lymphocytes, monocytes, eosinophils, basophils, adipocytes, chondrocytes, pancreatic islet cells, thyroid cells, parathyroid cells, parotid cells, tumor cells, glial cells, astrocytes, rad blood cells, white blood cells, macrophages, epithelial cells, somatic cells, pituitary cells, adrenal cells, hair cells, bladder cells, kidney cells, retinal cells, rod cells, cone cells, heart cells, pacemaker cells, spleen cells, antigen presenting cells, memory cells, T cells, B cells, plasma cells, muscle cells, ovarian cells, uterine cells, prostate cells, vaginal epithelial cells, sperm cells, testicular cells, germ cells, egg cells, leydig cells, peritubular cels, sertoli cells, lutein cells, cervical cells, endometrial cells, mammary cells, follicle cells, mucous cells, ciliated cells, nonkeratinized epithelial cells, keratinized epithelial cells, lung cells, goblet cells, columnar epithelial cells, dopamiergic cells, squamous epithelial cells, osteocytes, osteoblasts, osteoclasts, dopaminergic cells,, embryonic stem cells, fibroblasts and fetal fibroblasts. In a specific embodiment, pancreatic cells, including, but not limited to, Mets of Langerhans cells, insulin secreting cells, alpha-2 cells, beta cells, alpha-1 cells from pigs that lack expression of functional alpha-1,3-GT are provided.

Nonviable derivatives include tisssues stripped of viable cells by enzymatic or chemical treatment these tissue derivatives can be further processed via crossUnkmg or other chemical treatments prior to use in transplantation. In one embodiment, the derivatives include extracelluar matrix derived from a variety of tissues, including skin, urinary, bladder or organ submucosal tissues. Also, tendons, joints and hones stripped of viable tissue to include heart valves and other nonviable tissues as medical devices are provided.

The cells can be administered into a host in order in a wide variety of ways. Modes of administration are parenteral, intraperitoneal, intravenous, intradennal, epidural, intraspinal, intrastemal, intra-articular, intra-synovial, intrathecal, intra-arterial, intracardiac, intramuscular, intranasal, subcutaneous, infraorbital, intracapsular, topical, transdennal patch, via rectal, vaginal or urethral administration including via suppository, percutaneous, nasal spray, surgical implant, internal surgical paint, infusion pump, or via catheter. Ια one embodiment, the agent and carrier are administered in a slow release formulation such, as a direct tissue injection or bolus, implant, microparticle, microsphere, nanoparticle or nanosphete.

Disorders that can be treated by infusion of the disclosed cells include, but are not limited to, diseases resulting from a failure of a dysfunction of normal blood cell production and maturation (ie., aplastic anemia and hypoproliferative stem cell disorders); neoplastic, malignant diseases in die hematopoietic organs (e.g., leukemia and lymphomas); broad spectrum malignant solid tumors of non-hernatopoietic origin; autoimmune conditions; and genetic disorders. Such disorders include, but are not limited to diseases resulting from a failure or dysfunction of normal blood ceil production and maturation hyperproliferative stem cell disorders, including aplastic anemia, pancytopenia, agranulocytosis, thrombocytopenia, red cell aplasia, Blackfan-Diamond syndrome, due to drugs, radiation, or infection, idiopathic; hematopoietic malignancies including acute lymphoblastic (lymphocytic) leukemia, chronic lymphocytic leukemia, acute myelogenous leukemia, chronic myelogenous leukemia, acute malignant myelosclerosis, multiple myeloma, polycythemia vera, agnogenic myelometaplasia, Waldenstrom’s macroglobulinemia, Hodgkin's lymphoma, non-Hodgkin's lymphoma; immunosuppression inpatients with malignant, solid tumors including malignant melanoma, carcinoma of the stomach, ovarian carcinoma, breast carcinoma, small cell lung carcinoma, retinoblastoma, testicular carcinoma, glioblastoma, rhabdomyosarcoma, neuroblastoma, Ewing’s sarcoma, lymphoma; autoimmune diseases including rheumatoid arthritis, diabetes type I, chronic hepatitis, multiple sclerosis, systemic lupus erythematosus; genetic (congenital) disorders including anemias, familial aplastic, Fanconi's syndrome, dihydrofolate reductase deficiencies, formamino transferase deficiency, Lesch-Nyban syndrome, congenital dyserythropoietic syndrome I-IV, Chwachmann-Diamond syndrome, dihydrofolate reductase deficiencies, formamino transferase deficiency, Lesch-Nyhan syndrome, congenital spherocytosis, congenital elliptocytosis, congenital stomatocytosis, congenital Eh null disease, paroxysmal nocturnal hemoglobinuria, G6PD (glucose-6-phhosphate dehydrogenase) variants 1, 2, 3, pyruvate kinase deficiency, congenital erythropoietin sensitivity, deficiency, sickle cell disease and trait, thalassemia alpha, beta, gamma, methemoglobinemia, congenital disorders of immunity, severe combined immunodeficiency disease (SCID), bare lymphocyte syndrome, ionophore-responsive combined immunodeficiency, combined immunodeficiency with a capping abnormality, nucleoside phosphorylase deficiency, granulocyte actin deficiency, infantile agranulocytosis,

Gaucher's disease, adenosine deaminase deficiency, Kosftnann's syndrome, reticular dysgenesis, congenital Leukocyte dysfunction syndromes; and others such, as osteoporosis, myelosclerosis, acquired hemolytic anemias, acquired irnmunodeficiendes, infectious disorders causing primary or secondary immunodeficiencies, bacterial infections (e.g., Brucellosis, Listerosis, tuberculosis, leprosy), parasitic infections (e.g., malaria, Leishmaniasis), fungal infections, disorders involving disproportionsin lymphoid cell sets and impaired immune functions due to aging, phagocyte disorders, Kostmann's agranulocytosis, chronic granulomatous disease, Chediak-Higachi syndrome, neutrophil actin deficiency, neutrophil membrane GP-180 deficiency, metabolic storage diseases, mucopolysaccharidoses, mucolipidoses, miscellaneous disorders involving immune mechanisms, Wiskott-Aldrich Syndrome, alpha l-anfirypsin deficiency, etc.

Diseases or pathologies include neurodegenerative diseases, hepatodegenerative diseases, nephrodegenerative disease, spinal cord injury, head trauma or surgery, viral infections that result in tissue, organ, or gland degeneration. Such neurodegenerative diseases include but axe not limited to, AIDS dementia complex; demyeliriating diseases, such as multiple sclerosis and acute transferase myelitis; extrapyramidal and cerebellar disorders, such as lesions of the ecoxticospinal system; disorders of the basal ganglia or cerebellar disorders; hyperkinetic movement disorders, such as Huntington’s Chorea and senile chorea; drag- induced movement disorders, such as Arose induced by drugs that block CHS dopamine receptors; hypokinetic movement disorders, such as Parkinson’s disease; progressive supra-nucleo palsy; structural lesions of the cerebellum; spinocerebellar degenerations, such as spinal ataxia, Friedreich's ataxia, cerebellar cortical degenerations, multiple systems degenerations (Meucel, Dejerine Thomas, Shi-Drager, and Machado-Joseph), systennioc disorders, such as Rufsum's disease, abetabpoprotemia, ataxia, telangiectasia; and mitochondrial multi-system disorder; demyelinating core disorders, such as multiple sclerosis, acute transverse myelitis; and disorders of the motor unit, such as neurogenic muscular atrophies (anterior horn cell degeneration, such as amyotrophic lateral sclerosis, infantile spinal muscular atrophy and juvenile spinal muscular atrophy); Alzheimer’s disease; Down's Syndrome in middle age; Diffuse Lewy body disease; Senile Demetia of Lewy body type; Parkinson’s Disease, Wenucke-Korsakoff syndrome; chronic alcoholism; Cieutzfeldt-Jakob disease; Subacute sclerosing panencephalitis hallenrarden-Spatz disease; and Dementia pugilistica. See, e.g., Berkow et al, (eds.) (1987), The Merck Manual, (15th) ed.), Merck and Co., Rahway, NL lie non-human transgenic animals of the present invention can be used to screen any type of compound, for example, antibiotics, antifungals, antivirals, chemotherapeuti.es, cardiovascular drugs, and hormones. Compounds that can.be screened by using the animals of the present invention can be small molecules or biologies (e.g, proteins, peptides, nucleic acids). Compounds to be tested can be introduced to the animals of the invention via any delivery route known in the art, such as, but not limited to, intravenous injection, intramuscular injection, intraperitoneal injection, orally, sublingually, subcutaneously, via inhalation, iniranasally, intrathecally, ocularly, rectally, and traasdscmally.

The activity of the one or more compounds can be determined by measuring one or more biological or physiological responses of the cells of the animal. For example, cells or animals contacted with the one or more compounds to be screened (ie. "treated") are compared to "control" cells or animals that have been contacted with one or more inactive compounds (i.e. placebo(s) or other control treatments)), or in other embodiments, the control cells are not contacted with a compound. The response(s) of the cells or animals to the one or more compounds are then measured and comparisons between control and treated samples are made to determine the therapeutic effectiveness of the one or more compounds.

The activity of tee one or more compounds can be assessed by measuring the amount of target mKNA or protein produced in a cell. Analyzing "treated” and "control” cell samples allows for a quantitative comparison to determine tee therapeutic effectiveness of tee one or more compounds screened above that of the control sample. Alternatively, tee amount of compound associated with bote target and non-target proteins, cells, tissues or organs can be measured and compared to determine to pharmacokinetic profile of the one or more compounds of bote control and treated cells or animals. Assays for determining tee amount ofmRKA and protein in a cell are well known in tee art (see for example Sambrook, J. et al. "Molecular Cloning: A Laboratory Manual," 2nd addition, Cold Spring Harbor Laboratory Press, Plainview, "New York (1989)). Methods by which to measure tee amount of compound bound to a protein, cell, tissue or organ are also well known in tee art (see for example Appendix H and tee references therein in Gilman, et al., "Goodman and Gilman's The Pharmacological Basis of Therapeutics," Macmillan Publishing Co, Inc., New York (1980)).

Examples of biological responses of a cell or animal that can be measured to determine tee therapeutic effectiveness of one or more compounds include, but are not limited to, inflammation, generation of active oxygen species, cell lysis, cell death, immunological response (i.e. antibody production), protein production.

Examples of physiological responses of a cell or animal that can be measured to deteamine the therapeutic effectiveness of one or more compounds include, but are not limited to, temperature changes, pH changes, oxygen concentration, glucose concentration, blood flow, electro-physiologic properties.

Biological and physiological responses are determined by methods well known in the art, including but not limited to, spectroscopic analysis, microscopic or other visualization utilizing marker dyes and probes known in the art, instrumental monitoring (i.e. temperature, pH, blood pressure, blood flow, electrical measurements).

The term "therapeutically effective" indicates that the compound or composition has an activity that impacts a cell or an animal suffering from a disease or disorder in a positive sense and/or impacts a pathogen or parasite in a negative sense. Thus, a therapeutically effective compound can cause or promote a biological or biochemical activity within an animal that is detrimental to the growth and/or maintenance of a pathogen or parasites, or [within] cells, tissues or organs of an animal that have abnormal growth or biochemical characteristics such as cancer cells. Alternatively, a therapeutically effective compound can impact a cell or an animal in a positive sense by causing or promoting a biological or biochemical activity within the cell or animal that is beneficial to the growth and/or maintenance of the cell or animal. Whether (or the extent to which) a therapeutically effective compound impacts a cell or animal in a positive way (or a pathogen or parasite in a negative way) can be determined by examining the level of a given biological or biochemical characteristic or ftmction observed in the treated cell or animal and comparing that level to the level of the same biological or biochemical characteristic or function observed in an untreated control cell or animal, using art-known assays of a variety of biological or biochemical characteristics or functions. Any compound or composition that induces a change in the examined biological or biochemical characteristic or function in the treated cell or animal by an amount that is quantitatively discemable from that observed in a control cell or animal is said to be "therapeutically effective." A quantitatively discemable amount is any amount that is above the standard experimental error associated with the method or measurement used to determine therapeutic effectiveness. For example, a quantitatively discemable amount that can indicate that a tested compound or composition is therapeutically effective is a difference in the assayed characteristic or function in the treated cell or animal of about 1%, about 5%, about 10%, about 33%, about 50%, about 67%, about 75%, about 90%, about 95%, or about 100% relative to the level of the assayed characteristic or function in a control cell or animal. Ια one such embodiment of the invention, the transgenic cell to be contacted -with one or more compounds to be tested can be removed horn the transgenic animal and maintained and assayed in culture. This erabodjinent of the invention allows for a high throughput screening approach to assess foe therapeutic effectiveness of a compound, where multiple, different compounds could be tested on individual cells of foe same biologic type or animal species. Similarly, a single compound could be tested on many different cell types (e,g. muscle, bone, skin, neurologic) from a single animal species, or on cells ffom multiple species. Methods for mamtaining cells in culture axe well known in foe art (see for example Sambrook, J. et aL 'Molecular Cloning: A Laboratory Manual", 2nd addition, Cold Spring Harbor Laboratory Press, Plahmew, New York (1989) and Ereshney, R. L- "Culture of Animal Cells: A Manual of Basic Technique!," Alan R. Liss, Inc, New York (1983)).

Another embodiment of foe invention is a method of screening one or more compounds for a therapeutic effect on a human tumor that has been implanted into a nonhuman transgenic animal of foe invention, comprising: (a) implanting a human tumor or a human tumor cell into a transgenic animal; (b) contacting foe human tumor with one or more compounds to be tested; (c) measuring one or more biological or physiological responses of foe tumor to foe one or more compounds; and (d) determining foe therapeutic effectiveness of one or more compounds on foe human tumor.

Any non-human animal produced by my one of foe methods of foe present invention can be used as a tumor recipient, including but not limited to, non-human mammals (including, but not limited to, pigs, sheep, goats, cows (bovine), deer, mules, horses, monkeys and other non-human primates, dogs, cats, rats, mice, rabbits and foe like), birds (including, but not limited to chickens, turkeys, ducks, geese and foe like) reptiles, fish, amphibians and foe like.

Any human tumor or tumor cell line can be implanted into foe animal for screening purposes. Tumors include, but are not limited to, a breast cancer tumor, a uterine cancer tumor, an ovarian cancer tumor, a prostate cancer tumor, a testicular cancer tumor, a lung cancer tumor, a leukemic tumor, a lymphatic tumor, a colon cancer tumor, a gastrointestinal cancer tumor, a pancreatic cancer tumor, a bladder cancer tumor, a kidney cancer tumor, a bone cancer tumor, a neurological cancer tumor, a head and neck cancer tumor, a skm cancer tumor, a sarcoma, an adenoma and a myeloma. The tumor implanted into foe animal can be in foe form of a solid tumor mass, a single tumor cell, or multiple (i.e. 2,10, 50, 100, 1000) tumor cells. The tumor can be implanted in any tissue or organ of the animal, or can be delivered systemically. Any method known in the art by which to implant tumors and tumor cells into animals can be used in the present invention. Human tumors or tumor cells can come from any source, including but not limited to, established tumor cell lines, excised primary tumor tissue and commexciaygovermneot/academic sources including tissue banks and the like.

The non-human transgenic animal of the invention with the implanted human tumor can be used to screen small molecules or biologies (e.g. proteins, peptides, nucleic acids). Compounds to be tested can be introduced to the animals of die invention via any delivery route known in the art, such as, but not limited to, intravenous injection, intramuscular injection, intraperitoneal injection, orally, sublingually, subcutaneously, via inhalation, intranasally, intrafhecally, ocularly, rectally, and transdermally.

The activity of the one or more compounds can be determined by measuring one or more biological or physiological responses of the human tumor implanted into the animaL For example, the activity of the compounds can be assessed by measuring the amount of target mKNA or protean produced in a cell. Alternatively, the amount of compound associated with both target and non-target proteins, cells, tissues or organs can be measured and compared. Assays for determining the amount of mKNA and protein in a cell are well known in the art.

Examples of biological responses of an implanted human tumor that can be measured to determine the therapeutic effectiveness of one or more compounds include, but are not limited to, inflammation, generation of active oxygen spades, cell lysis, immunological response (ie. antibody producticsn), protein production, and the like.

Examples of physiological responses of an implanted human tumor that can be measured to determine the therapeutic effectiveness of one or more compounds include, but are not limited to, temperature changes, pH changes, oxygen concentration, tumor growth, glucose concentration, blood flow, and the like.

In this context, the term "therapeutically effective" indicates that the compound has an activity that impacts the implanted human tumor in a negative sense. Thus, a therapeutically effective compound can cause or promote a biological or biochemical activity within an animal that is detrimental to the growth and/or maintenance of the tumor.

The present invention also provides therapeutically effective compounds identified using any one of the screening methods of the present invention. These compounds can be small molecules or biologies. In such an embodiment, the compounds can contain one or more pharmaceutically acceptable carrier or excipient The compounds provided by the screening methods of the present invention can produce any level of therapeutic effectiveness that is discemable relative to control.

EXAMPLES

Example 1: Targeting families of genes

For specific targeting of a family of genes, a desired subset of genes, or specific alleles of a gene or gene family, a representative sample of sequences is obtained. These sequences are compared to identify areas of similarity. The comparison determines areas of similarity and identity between given gene families, as well as within subsets of sequences within a family. In addition, tins analysis determines areas of similarity and identify between alleles of family members. By considering these sequences, regions axe identified that can be used to target either the entire family, subsets of family members, individual family members, subsets of alleles of individual family members, or individual alleles of family members.

The results of a typical analysis are shown in Figure 8. In this analysis, Region 2 can target all members of the given 4-gene family. likewise, the sequence of Region 3 differentiates Gene 1 and 2 from Gene 3 and 4, and Region 4 can be used to differentiate Gene 1 and 4 from Gene 2 ami 3, Region 5 can be used to differentiate Gene 1, Allele A and B from all other family members, while Region 1 or Region 6 can specify individual alleles of any gene in 1he family.

After potential targets regions are identified, a “reporter'’ construct (vector) that includes, but need not be limited to, one or more potential target regions is constructed. The expression of the reporter construct is measurable, either by measuring the output of the target gene or by measuring output of an additional gene, such as a fluorescent reporter (readout). The reporter construct is introduced to a cell or a cell population. In addition to the reporter construct, iRNA constructs are assembled that encode potential iRNA molecules. The iRNA constructs can be assembled by, for example, combining DNA fragments that include sequences that serve as a promoter of transcription and sequences that represent an iRNA molecule to be tested (see Figure 5). The test constructs are also introduced into the above cultured cells. Measurement of the reporter construct readout indicate efficacy of the iRNA molecule(s), such that if the transgene encodes an effective iRNA molecule, the readout of the reporter molecule is altered. Test constructs that successfully provide down regulation of the reporter gene provide iRNA sequences that are used alone or in combination to produce transgenic animals. Methods of introducing the iRNA molecules into cells to produce transgenic animals include homologous recombination using endogenous or exogenous promoters. The resulting animals enjoy reduced expression of a targeted gene family, subsets of genes within a given family, individual genes, subsets of alleles of individual genes, or individual alleles of a single gene.

In the exemplary analysis shown in Figure 8, subsets of genes or alleles may not contain unique targeting regions that are present in every member of the subset, In such cases, multiple constructs are used so that each iRNA molecule specifies at least one member of the desired target gene subset but none of the members of the excluded targets. Therefore, the group of iRNA molecules specify a unique subset of targets even though no single molecule in the group of iRNA transcripts is capable of targeting all members of the desired subset.

After identifying sequences that affect a target or set of targets, additional constructs are developed to fully reduce the expression of the targets). Constructs are developed that provide collections of iRNA molecules or sets of molecules that target specific genes, families of genes, or alleles within a family. These grouped constructs are developed by combining multiple test construct sequences, or by assembly of a new construct that encodes multiple copies of iRNA or groups of iRNA targeting molecules.

In the example analysis shown in Figure 8, a combination of test constructs that are effective against the vertical stripped sequence, horizontal stripped sequence, and bricked sequence in Region 5 down-regulate all slides of Gene 1 and Gene 3. On the other hand, in this set of grouped constructs, omission of a construct specifying the horizontal stripped sequence in Region 5 results in targeting Gene 1, Allele A and B, and all slides of Gene 3.

Example 2 - Use of SNA interference to inhibit Porcine Endogenous Retrovirus RNA interference is used to heritably suppress expression of a family of related sequences encoding different yet homologous retroviruses found in pigs. Broadly, a transgene is constructed that results in production of an iRNA molecule with souse and inverted antisense sequences, homologous to a region of the porcine endogenous retrovirus genome that is conserved between PERV variants, at least three of which are known (PBRV-A, -B and -Q. The transgene is added to the genome of a pig to produce a genetic line that heritably expresses an RNA molecule that can self hybridize to form dsRNA. This RNA induces interference of expressed porcine endogenous retrovirus in each cell that expresses the transgene. Not only is total PERV production severely down regulated, but xecombiradon between targeted variants may not produce a novel untargeted variant. Cells, tissues, or organs from such, animals can be used for xenotransplantation, with reduced risk of PERV transmission.

Step 1:

Assays are developed to quantify the effectiveness of individual iRNA molecules. In addition, a reporter vector is constructed to allow streamlined screening of iKNAs and an iRNA expression vector assembled to allow efficient insertion of individual potential iRNA-encoding sequences. Potential targets are identified by sequence analysis of the family of target PERVs.

Model-gene control plasmids: Based on sequence conservation, primers are designed and used to amplify gag, pol, and env coding regions from both the cell line PK-15, a ceil line known to shed infective PERVs (Le Tissier et al., 1997), and in fetal fibroblasts (including al,3-GT knockout fibroblasts). The most highly expressed coding region from each gene is used to build a model reporter construct. Each reporter construct is assembled by inserting a PERV coding region (gag, pol, or env) between a reporter molecule coding region and its poly(A) signal. The plasmids thus produce an mRNA with a reporter gene (i.e. β-Gal, GPP) upstream of a potential iRNA target (in the 3’ non-coding region). The effectiveness of individual iRNA molecules is assayed by analyzing suppression of the reporter gene expression. The protocol can also be modified to analyze non-coding PERV sequence in lieu of, or addition to, the coding sequences. iRNA expression plasmids: Several RNA polymerase ΠΙ (Pol ΙΠ) dependent promoters are amplified, cloned, and tested for ubiquitous expression in transgenic animals. Pol ΠΙ promoters can drive expression of iRNAa without addition of terminal sequence (i.e. a poly(A) tail). The Pol ΠΙ promoters may include the promoters from H1RNA, snRNAUti, 7SK, MRP RNA, or 7SL. Pol ΙΠ promoters can be screened to choose a promoter with ubiquitous expression. An iRNA test vector is assembled, including a cloning region and a poly(U)-dependent Pol ΙΠ transcription terminator. Protein coding regions may also be provided within the gene for the interfering RNA. PERV assays: Specific probes against PERV-A, -B and -C are developed to detect corresponding proviral PERV DNA sequences. PCR assays for proviral PERV DNA utilize primers specific to gag, pol and env regions, as well as to an internal control gene such as the β-globulin gene. Real-time PCR with primers specific to porcine mitochondrial DNA (mtDNA) or centromeric sequences is used to quantify porcine cell contamination (chimerism) in transinissibxKty assays. PCR primers specific to gag and pol regions of PERV are also developed to detect PBRV RNA in target samples.

Step 2:

An ideal target for iRNA is a region of the PERV mRNA that is conserved across most PERVs. Such. sequences are identified for initial constructs. Analysis of all known PERV sequences and additional PERY sequences that arise fiom this effort provide information for logical design of iKNA vectors. All iKNA vectors are tested for function in cell assays before use in transgenic animal production.

Bioinformatics: Analysis of all available PERV env mRNA sequences is shown in Figure 9. This analysis is performed to detennine both regions of conservation and consensus sequences. An effective iRNA targeted to the region between 6364bp and 6384bp will target all PERY env genes shown in this example. Alternatively, a pair of effective iRNA molecules targeted to the two sequences in the region between 6386bp and 6407bp would also target all PERV env genes shown in this example. An attempt to target sequences that include die region fiom 6408bp to 643lbp requires three effective iKNA molecules, each targeting one of the three represented sequences. Likewise, targeting a region that includes base 6385 also requires three effective iKNA molecules.

Because the sequence analysis is limited to the experimental sequence obtained, it is possible that not all PERV sequences are represented, β is possible that an unknown or undescribed variant exists. The identified iRNAs are therefore re-tested for effectiveness against the native target instead of an artificial marker gene. Any mRNA that escapes interference is cloned and added to the analysis. The entire process is repeated until all mRNA is repressed.

Another method of selecting potential targets for interfering RNA is shown in Figure 10. An 86 base consensus for a semi-conserved region of PERV is shown on the first line (line 1, underlined and bold text). Sixty-eight potential 19 base targets for inhibitory RNA within this sequence are shown on subsequent lines (lines 2-69). Targets are between 17 and 35 bases in length and ideally between 21 and 25 bases in length. This process is reiterated for targets of 17-35 bases and can be applied to any region, protein coding or non-coding, included within any complete or partial PBRV genome. All PERV sequences are potential targets. In this example, sequences of a fixed length of 19 nucleotides are selected as potential targets.

In addition to the simplified screen shown in Figure 10, bioinfoimatics can he used to reduce non-specific target sequences. As shown in Figure 11, targeted genes may share homology with non-targeted genes, hi this case, potential targets that share significant homology with non-targeted genes are eliminated fiom the screening process. KNA sequence of target genes are screened for homology to ηαη-targeted KNAs. A19 base region of an unknown porcine expressed sequence (Genbank entry BB05054) is significantly homologous to a region of semi-conserved PERV sequence (shown in black face bold type and underlined). Though potential target regions with significant homology to non-targeted RNAs can prove useful, such target regions are excluded in initial target screens to reduce the risk of severely down-regulating unintended gene products. Line 1 of Figure Π represents PERV sequence. Lines 2-69 represent targeted PERV sequence identified by bioinformatics. Line 70 represents an unknown expressed porcine sequence. lines 36-56 represent the result of fee sequence analysis, illustrating the excluded targets.

Figure 12 illustrates an example of a proposed three dimensional configuration of an expressed iRNA. The ERNA is designed for fee target sequence 5’AAT TGG AAA ACT AAC CAT C 3 (Figure 10, Line 2). An exemplary iRNA sequence is 5’(Νγ) AAU UGG AAA ACU AAC CAU C(NY)G AUG GUU AGU UUU CCA AUU (Νγ) 3’ (wherein "N" refers to any nucleotide and T refers to any integer greater than or equal to zero). Each portion of non-specified sequence, (Νγ), can be homopolymeric. The nonidentical sequence can also be composed of non-identical bases. In addition, any continuous stretch of non-specified sequence, (Νγ), can provide additional functions such as but not limited to encoding protein, providing signals for stability or increased half-life, increasing the length of palindromic sequence, providing signals and functions for splicing, or folding into particular structures.

Step 3:

Tissue culture confirmation: Based on the sequences and plasmids identified in Steps 1 and 2, multiple individual iRNA expressing plasmids are designed, constructed and tested for function in tissue culture using fee protocol described in Step 1. Each £KMA plasmid is tested for stable expression and effectiveness against fee a reporter plasmid containing the appropriate target sequence. Interference activity against native PERV mRNAs is established experimentally. In addition, reduction in PERV mRNA is correlated wife a decrease in viral particle production.

Each selected iRNA construct is transfected into PK-15 cells, which axe known to feed humm-transmissible PERVs. Each selected iRNA construct is tested for ability to reduce steady-state mRNA, reduce the number of viral particles shed, and reduce fee transmissibility of PBRVs to human cells, ha addition, any PERV mRNAs that are found after the first round of testing, are amplified by RT-PCR and sequenced. These sequences are analyzed to determine individual polymorphisms that allow mRHA. to escape iRNA. This information is used to further modify iRNA constructs to target rare polymorphisms.

After identification of individual iRNA constructs, groups of constructs are developed that will effectively eliminate expression of PERV in selected cells. The specific sequences included in the groupings are identified using the methods described in the previous steps.

Step 4:

Creation ofPERV-free cells: An alpha-GT knock out line or a line of pigs that express complement inhibiting proteins is used, however a PBRV-free genetic background can be achieved using any line of swine. Fibroblasts are engineered with IRNA constructs to allow a degree of functional testing prior to generating animals. These cells are also screened for integration sites to analyze functional effects. The use of fibroblasts is advantageous ova: other methods of producing transgenic animals, where normally one can only assay integration-site-specific traasgene expression after the animals are bom.

Primary alpha-1,3-GT knockout fetal fibroblasts are engineered to express functionally-screened, optimized iRNA designed in Steps 1 to 3. Individual colonies of cells, each representing unique integration events, are selected. These colonies are propagated and a subset is stared (frozen) for later screening for gene expression and function. The stored cells may also serve to provide cells for somatic cell nuclear transfer.

Function is established for each cell line’s unique PERVs. Each colony of fibroblasts containing genome integrated iRNA is tested for reduced steady-state PERV ruRNA. Any surviving PERV mRNAs is amplified by RT-PCR and sequenced. These sequenced mRNAs are analyzed to determine individual polymorphisms that allow these mRNAs to escape current iRNAs. This information is used to further modify iRNA constructs to target rarer polymorphisms.

Step 5:

Somatic cell nuclear transfer allows for an efficient, relatively inexpensive and relatively fast production of transgenic pigs. Cells that have been developed and screened in Step 4 (alpha-1,3 GT knockout fibroblasts engineered to contain optimized, functional, PERV-suppreBsing iRNAs) are used as nucleus donors in somatic cell nuclear transfer. The technique of somatic cell nuclear transfer includes removing the nucleus from an oocyte of a pig, then fusing or inserting the nucleus from the fibroblast into the enucleated oocyte. The cells are then grown to the blastocyte stage and them frozen and implanted in a sow.

Though tissue culture experiments with: PK-15 cells and fetal fibroblasts will prove very useful, to date no in vitro assay exists to perfectly model m vivo transgene function. In addition, some tissue specific variation may exist in both iRNA function and PERV mRNA expression. Analysis of fetal tissues of transgenic pigs allows more extensive analysis of iRNA utility.

Mid-gestation fetuses are collected. Tissues are harvested and analyzed for iRNA expression and PERV mRNA suppression. Integration sites that provide effective PERV suppression are selected. Somatic cell nuclear transfer allows fox the generation of transgenic pigs that have identical integration events aa the screened fetuses. Cloning allows cells that are being propagated, recovered from storage, or cells collected horn the mid-gestation fetuses, to be used to make transgenic animals. Cells that have been screened and wherein PERV has been effectively eliminated are used as nucleus donors in somatic cell nuclear transfer. Reconstructed embryos axe transferred to recipient females and allowed to develop to term.

The full elimination of PERV is confirmed in live animals. Piglets are sacrificed at various stages of maturity and analyzed for transgene expression and suppression of PERV mRNA In addition, multiple tissues are tested to ensure that PERV is eliminated in therapeutically useful organs.

Specific PBRV Targets

The specific gag, pol and env sequences of PERV that were used to identify potential siRNA targets are listed below. Each sequence is a subset of the full length gene. The subset represents the portion of each gene that we used to assemble the model genes. Regions that are to be excluded from consideration have been replaced with a homopolymer (ttttt...t, or GGGG..G) gag

GGACAGACGGTGAAGACCCCCCTTAGTTTGACTCTCGAAAATTGGACTGAAGTTA

GATCCAGGGCTCATAATTTGTCAGTrCAGGTrAAGAAGGGACCTTGGGAGATTTC

CCGTGCCTCTGAATGGCAAACATrCGATGTTGGATGGCCATCAGAGGGGACTTTT

AA.TTCTGAAATTATCCTGGK3TGTTAAAGCAATCATTTTTCAGACTGGACCCGGCT

CTCATCCTGATCAGGAGCCCTATATCCTTACGTGGCAAGATTTGGCAGAAGATCC

TCCGCCATGGGTTAAACCATGGCTATGGGGGGGGGGGAGCCAGGCCCCCGAATC

CTGGCTCTTGGAGAGAAAAACAAACACTCGGCCGAAAAAGGGGGGGGGGGTCCT

CATATCTACCCCGAGATCGAGGAGCCGCCGACTTGGCCGGAACCCCAACCTGTTC

CGGGQGGGGGGGTTCCAGCACAGGGTGCTGCGAGGGGACCCTCTGCCCCTCCTG gagctccggtggtggagggacctgctgccgggactcggagccggagaggcgcca ccccggagcggacagacgagatcgcgatattaccgctgtggacctatggccctcc

CATGGCGGGGGGCCAATTGCAGCCCCTCCAGTATTGGCCCmTdTCXGCAGAT

CTCTATAATTGGAAAACTAACCATCCCCCTTTCTCGGAGGATCCCAACGCCTCAC

GGGGTTGGTGGAGTCCCTTATGTTCTCTCACCAGCCTACTTGGGATGATTGTGAA

GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGAATTCTGTTAG

AGGCTAGAAAAAATGTTCCTGGGGCCGACGGGCGACCCACGCAGTTGCAAAATG

AGATTGACATGGGATTTCCCTTGACTCGCCCCGGTTGGGACTACAACACGGCTGA

AGGTAGGGAGAGCTTGAAAATCTATCGCCAGGCTCTGGTGGCGGGTCTCCGGGG

CGCCTCAAGACGGCCCACTAATTrGGCrAAGGTAAGAGAGGTGATGCAGGGACC

GAACGAACCTCCCTCGGTATTTCTTGAGAGGCTCATGGAAGCCTTCAGGCGGTTC

ACCCCTTTTTGGGGGGGGGGGGGGGGGGGGGGGGCCT CAGT GGCCCTGGCCTT C

ATTGGGCAGTCGGCTCTGGATATCAGAAAGAAACTTCAGAGACTGGAAGGGTTA

CAGGAGGCTGAGTTACGTGATCTAGTGAGAGAGGCAGAGAAGGTGTATTACAGA

AGGGAGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

GGGGGGGOGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

GGGGGGGGGGGGGGGGGGGGGGGGGGAAAAAGGACACTGGGCAAGGAACTGC CCCAAGAAGGGAAACAAAGGACCGAATTTCCTATTTCTAGAAGAA (Seq ID No 6) pol

GGCAACGGCAGTATCCATGGACrACCOGAAGAACCGTTGACTTGGCAGTGGGAC GGGTAACCCACTCGTTTCTGGTCATCCCTGAGTGCCCAGTACCCCTTCTAGGTAG AGACTTACTGACCAAGATGGGAGCTCAAATTTCTTTTGAACAAGGAAGACCAGA AGTGTCTGTGAATAACAAACCCATCACTGTGTTGACCCTCCAATTAGAIXjATGAA TATCGACTATATXCTCCCCAAGTAAAGCCTGATCAAGATATACAGTCCTGGTTGG agcagtttccccaagcctgggcagaaaccgcagggatgggtttggcaaagcaag

TTCCCCCACAGGTTATTCAACTGAAGGCCAGTGCTACACCAGTATCAGTCAGACA gtaccccttgagtagagaggctcgagaaggaatttggccgcatgttcaaagatt AATCCAACAGGGCATCCTAGTTCCTGTCCAATCCCCTTGGAATACTCCCCTGCTA CCGGTrAGGttttttttttttttttttttttttttttttttttttttGAGAGAGGTCAATAAAAGGGTGcaggacatacac ccaacggtcccgaacccttataacctcttgagcgccctcccgcctgaacggaactggtacacagtattggacttaaaagatgccttcttc tgcctgagattacaccccactagccaaccgctfctttgccttcgaatggagagatccaggtacgggaaGAACCGGGCAG-Cttt

fttfHrtf+ttmH 11111II i.ui.LLLlilltttttttttttttACGAAGCCCTACACAGGGACCTGGCCAACTTCAGG ATCCAACACCCCCAGTGACCCTCTCCAGTACTGGGATGACCTGCTTCTAGTGGAG CCACCAACAGGACTGCTAGAAGGTACGAAGGCACXACTACTGAATTGTCTGACC TAGGCTACGAGCCTCAGCTAAAAGGCCCAGATTGCAGAGAGAGGTAACATACTT gggtacagtctgcgggacgggcagtgatggctgacggaggcacggaagagaac

TGTAGTCtAGATACCMtttttitttttttttCAAGTGAGAGAGTTTTGGGGGACAGCTGGATT TrGCAGACTGTGGATCCCGGGGTTTGCGACXrrTAGCAGCCCCACTCTACCCGCTA accaaagaaaaaggggagttctcctgggctcctgagcaccagaaggcatttgat gctatcaaaaaggccctgctgagcacacctgctctggccctccctgatgtaacta aaccctttactctttatgtggatgaatgtaagggggtagcccggggagttttaac ccaatccctaggaccatggaggagacctgttgcctacctgtcaaagaagctcgat CCrGTAGCCAGTGGTTGGCCCATATGCCTGAAGGCTATCGCAGCCGTGGCCATAC tggtcaaggacgctgacaaattgactttgggacagaatataactgtaatagccc cccatgcgttggagmcatcgtccggcagcccccagaccgatggatgaccaacg cccgcatgacccacxatcaaagcctgcttctcacagagaggatcacgttcacxct ACCAGCTGCTCTCAACCCTGCCACTCITCrGCCTGAAGAGACTGATGAACCAGTG A (Seq ID No 7)

ftTtV

rATCCCACGTTAAGCCGGCGCCACCTCCCGATTCGGGGTGGAAAGCCGAAAAGA

rTGAAAATCCCCTTAAGCTTCGCCTCCATCGCGTGGTTCCTTACTCTGTCAATAAC

rTCTCAGACTAATGGTATGCGCATAGGAGACAGCCTGAACTCCCATAAACCCITA

TCTCTCACCTGGTTAATTACTGACTCCGGCACAGGTATrAATATCAACAACACTC

AAGGGGAGGCTCCTTTAGGAACCTGGTGGCCTGATCTATACGTTTGCCTCAGATC

AGTrATTCCliilUttimiltttttUIxmmuttttTCCATGCTCACGGATTTTATGTTTGCCCAGGA

CCACCAAATAATGGAAAACATTGCGGAAATCCCAGAGATTTCTTTTGTAAACAAT

GGAACrGTGTAACCTCTAATGATGGATATTGGAAATGGCCAACCTCTCAGCAGG ATAGGGTAAGTrTTTCTrATGTGAAltLULltttttUtttltataLUUmtLttmiliLLLlLULLttttttttttttattlUttm;

»11111 iintttttflrAGA'nACCTAAAAATAAGTTTCACTGAGAAGGGAAAC CAAGAAAATATCCTAAAATGGGTAAATGGTATGTCTTGGGGAATGGTATATTATG GAGGCTCGGGTAAACAACCAGGCTCCATTCTAACTATTCGLIilUlLLmaLUttmLILCCTCC AATGGCTATAGGACCAAATACGGTCTTGACGGGTCAAAGACCCCCAACCCAAGG ACCAGGACCATCCTCTAACATAACCTCTULmLUtLiaiLtaiLtttltlHttmiaU.Utt[LU.tttUUtUiUtULttl tttHtttttttttttttttCTAGCAGCACGACrAAAATGGGGGCAAAACTTmAGCCTCATCCA GGGAGCTTTTCAAGCTCTTAACTCCACGACTCCAGAGGCTACCTCTTCTTGTTGGC TATGCTTAGCTTTGGGCCCACCITACTATGAAGGAATGGCTAGAAGAGGGAAATT caatgtgacaaaagaacatagagaccaatgcacatggggatcccaaaataagct

TAC(XTrACTGAGGTTTCTGGAAAAGGCACCTGCATAGGAAAGGTTCCCCCATCC

CACCAACACCTTTGttimiliUtttttlltttUULCCrCTGAGAGTCAATATCTGGTACCTGGTTA

TGACAGGTGGTGGGCATGTAATACTGGATTAACCCCTTGTGTTTCCACCTTGGTTT

TTAACCAAACTAAAGATmTGCATTATGGTCCAAATTGTTCCCCGAGTGTATTAC tatcccgaaaaagcaatccttgatgaatatgactacagaaatcatcgacaaaag

AGAGGACCCATATCTCTGACAGrTGCTGTGATGCTCGGACTTGGAGTGGCAGCAG

GTGTAGGAACAGGAACAGCTGCCCTGGTCACGGGACCACAGCAGCTAGAAACAG

GACITAGTAACCTACATCGAATTGTAACAGAAGATCTCCAAGCCCrAGAAAAAT

CrGTCAGTAACCTGGAGGAATCCCTAACCTCCTTATCTGAAGTAGTCCTACAGAA TAGAAGAGGGTTAGATTTATTATTrCTAAAAGAAGGAGGATTATGTGTAGCCTTtti

ttttmun1 M mi n iniuuttttttttttGACTCCATGAACAAACTTAGAGAAAGGTTGGAGAAG

CGTCGAAGGGAAAAGGAAACTACTCAAGGGTGGTTTGAGGGATGGTTCAACAGG

TCTCCTTGGTTGGCTACCCTACTrTCTGCTTTAACAGGACCCTTAATAGTCCTCCT

CCTGTTACTCACAGTTGGGCCATGTATTATTAACAAGTTAATTGCCrTCATTAGAG 8)

The specific siRNA sequences that were derived from these model gene sequences are listed below.

Table 1:

Oligonucleotides were designed, built, annealed, and cloned into an siRNA expression plasmid. The siRNA expression plasmids were screened far effectiveness with the appropriate model gene (anti gag siRNA with a gag model, anti-pol siRNA with a pol model, ect.) in mammalian cells. Most of the siRNA expression plasmids displayed some level of effectiveness. The most potent anti-gag expression plasmid (g49) and the most potent anti-pol expression plasmid (pl06) were confirmed effective against PEECV mRNA in transfections of PK-15 cells. This effect was assayed by both detection of PERV-produced reverse transcriptase activity and direct measurement of PERV mRNA iRNA expression plasmids:

Portions of gag, pol, envA, envB, and envC were amplifed and cloned into pCR-XLTOPO (Ihvitrogen, Carlsbad, CA). Each insert was independently sublconed as an Xbal/Spel fragment into a house vector pPL732.8 at an Xbal site located between the coding region of a reporter gene and its poly(A) signal. A graphic representation of the strategy in Figure 13.

For each iRNA, oligos were cloned into psiRNA-Hlneo (MvivoGen, San Diego, CA) according to the manufacturers recommendations, hi brief, the oligos were annealed and cloned into the Bbsl sites in place of the LacZ alpha peptide for blue/white screening. For each plasmid, iRNA integrity was confirmed by sequencing.

To test for robust function of each iRNA the appropriate model gene and a single iRNA test vector were co-transfected into CHO or PK-15 cells using GenePORTER (Gene Therapy Systems, Inc. (GTS), San Diego, CA ) according to the manufacturers suggestions. As controls, cells were also co-transfected with the reporter gene and an anti-GFP iRNA vector or with the report»: and a non-fimctional, negative control iRNA consruct. Suppression of the either the total level of reporter expression per transfected cell (as measured by FACS) or the proportion of cells that expressed the reporter gene (visual appraisal or FACS) was considered indicative of iRNA function. The apparently most potent iRNA for both gag and pol were independently transfected into PK-15 cells without the reporter model gene. To determine suppression of viral particle production, reverse transcriptase was measured in the medium of these cells using a commercially available kit (Cavidi Tech, Uppsala, Sweden). Additionally, stable colonies were isolated fear each IRNA and the level of steady-state mRNA was measured via quantitative RTPCR. These colonies were also assessed for RT activity and. their ability to suppress transiently transfected model gene.

Additional PERV Targeting Strategies: Identification of Prosha Substrates

The following sequence (Fragment A) represents a portion of PERV pol in which potentially non-unique sequence has been replaced with an equal number of lower case •V.

Fragment A:

GGCAACGGCAGTATCCATGGACTACCCGAAGAACCGTTGACTTGGCAGTG

GGACGGGTAACCCACTCGTTTCTGGTCATCCCTGAGTGCCCAGTACCCCT

TCTAGGTAGAGACTTACTGACCAAGATGGGAGCTCAAATTTCTTTTGAAC

AAGGAAGACCAGAAGTGTCTGTGAATAACAAACCCATCACTGTGTTGACC

CTCCAATTAGATGATGAATATCGACTATATTCTCCCCAAGTAAAGCCTGA

TCAAGATATACAGTCCTGGTTGGAGCAGITTCCCCAAGCCTGGGCAGAA

ACCGCAGGGATGGGTTTGGCAAAGCAAGTTCCCCCACAGGTTATTCAAC

TGAAGGCCAGTGCTACACCAGTATCAGTCAGACAGTACCCCTTGAGTAGAGA

GGCTCGAGAAGGAATTIGGCCGCATGTTCAAAGATTAATCCAACAGGGCA

TCCrAGTTCCfGTCCAATCCCCTTGGAATACTCCCCTGCTACCGGTTAGG

UllttLttltltttltillUULlLLmtttttttGiGAGAGGrG^ TAAAAGGGTGcaggacaiacacccaacggtcccgaacccttataacctct tgagcgccctcccgcctgaacggaactggtacacagtattggacttaaaa gatgccttcttctgcctgagattacaccecactagccaaccgctttttgc cttcgaatggagagatccaggtacgggaaGAACCGGGCAGCttttttttt

tttmttlLtliLttlLtLtLtlLIhULtdttttttlACGAAGCC

fTACACAGGGACCTGGCCAACTTCAGGATCCAACACCCCCAGTGACCCTC

TGr.AGTACTGGGATGACCTGCTTCTAGTGGAGCCACCAACAGGACTGCTA gaaggtacgaaggcactactactgaattgtctgacctaggctacgagcct

GAGCTAAAAGGCCCAGATTGCAGAGAGAGGTAACATACTTGGGTACAGTC

TfiGGGGACGGGCAGTGATGGCTGACGGAGGCACGGAAGAGAACTGTAGTC

AGCTGGATTTTGCAGACTGTGGATCCCGGGGTTTGCGACCTTAGCAGCCC

CACrCTACCCGCTAACCAAAGAAAAAGGGGAGTTCrCCTGGGCTCCTGAG

CACCAGAAGGCATTTGATGCTATGAAAAAGGCCCTGCTGAGCACACCTGC

TCTGGCCCTCCCTGATGTAACTAAACCCXTTACTCTTTATGTGGATGAAT

GTAAGGGGGTAGCCCGGGGAGTTTTAACCCAATCCCTAGGACCATGGAGG

AGACCTGTTGCCTACCTGTCAAAGAAGCTCGATCCTGTAGCCAGTGGITG

GCCCATATGCCTGAAGGCTATCGCAGCCGTGGCCATACTGGTCAAGGACG

CTGACAAATTGACTTTGGGACAGAATATAACTGTAATAGCCCCCCATGCG

TTGGAGAACATCGTCCGGCAGCCCCCAGACCGATGGATGACCAACGCCCG

CATGACCCACrATCAAAGCCTGCTTCTCACAGAGAGGATCACGTTCACTC

TACCAGCTGCTCTCAACCCTGCCACTCTTCTGCCTGAAGAGACTGATGAA CCAGTGA (Seq ID No 9)

Hie section of pol shown mderlined above has been converted to its complement below (Fragment B);

Fragment B.

GGTATCTGGACTACAGTTCTCTTCCGTGCCTCCGTCAGCCATCACTGCCC

GTCCCGCAGACTGTACCCAAGTATGTTACCTCTCTCTGCAATCTGGGCCT

TTTAGCTGAGGCTCGTAGCCTAGGTCAGACAATTCAGTAGTAGTGCCTTC

GTACCTTCTAGCAGTCCTGTTGGTGGCrCCACTAGAAGCAGGTCATCCCA

GTACTGGAGAGGGTCACTGGGGGTGTTGGATCCTGAAGTTGGCCAGGTCC CTGTGTAGGGCTTCGT (Seq ED No 10) MFold (M. Ztiker. Mfold web server for nncledc add folding and hybridization prediction. Nucleic Adds Res. 31 (13) 3406-15, (2003), (ht±p^/www.bioinfo.rpi.edi^applicaticms/mfold/old/ma/forml.cgi]) was nsed to produce the foEowing “folded” structure prediction of Fragment B:

In the above structure, bases 118-248 form a significant hairpin structure. Bases 147-166 (CTTCGTACCTTCTAGCAGTC (Seq JO No 11)) and bases 199-218 (ACTGGAGAGGGTCACTGGGG (Seq ID No 12)) were used to design &amp;Drosha substrate with a mir-30 loop and base. The MFold predicted structure of that substrate is:

The nucleotide sequence of the above sequence is GAUCUGCGGCCUUCGUACCUUCUAGCAGUCGUGAAGCCACAGAUGGACUG GAGAGGGUCACUGGGGUGCUGAUC (Seq ID Nol3).

In a similar manner, bases 192-214 (GTCATCCCAGTACTGGAGAGGGT (Seq ID Nol4))and bases 155-178 (CTTCTAGCAGTCCTGTTGGTGGCT (Seq ID Nol5)) were used to design a Drosha substrate with a mir-30 loop and base. The MFold predicted structure of that substrate is:

The nucleotide sequence of the above sequence is GAUCUGCGCGUCAUCCCAGUACUGGAGAGGGUGUGAAGCCACAGAUGCCU UCUAGCAGUCCUGUUGGUGGCUUGCUGAUC (Seq ID Nol6).

Likewise, bases 118-139 (GCCTAGGTCAGACAATTCAGTA (Seq ID NolT)) and bases 230-251 (ATcCTGAAGTTGGCCAGGTCCC(Seq ID Nol 8)) were used to design a Drosha substrate with amir-30 loop and base. The lowercase “c” at base three of the second oligo was changed to an “A” to optimize folding. The MFold predicted structure of that substrate is:

The nucleotide sequence of the above sequence is GAUOTGCGAGGGCXnJAGGUCAGACAAUUCAGUAUGUGAAGCCACLAGAUGA UAOJGAAGUUGGCCAGGUCCCXrGCUGAUC (SeqIDNol9).

Fragment C is shown below and is the complement of the sequence shown in italics above in Fragment A

Fragment C: gctgcccggttcttcccgtacctggatctctccattcgaaggcaaaaagc ggttggctagtggggtgtaatctcaggcagaagaaggcatcttttaagtc caatactgtgtaccagttccgttcaggcgggagggcgcteaagaggttat aagggttcgggaccgttgggtgtatgtcctgcacccttttattgacctct etc (Seq ID No 20) A folded Fragment C structure predicted by MFold shown below:

in die above structure, bases 142-200 form a significant hairpin structure. Bases 141-163 (AAGAGGTTATAAGGGTTCGGGAC (Seq ID No 21)) and bases 176-201 (GTCCTGCACCCTTTTATTGACCTCTC (Seq ID No 22» were used to design a Drosha substrate with a mir-30 loop and base. The MFold predicted structure of that substrate is:

The nucleotide sequence of the above sequence is GAUCUGCGAAGAGGUUAUAAGGGUUCGGGACGXJGAAGCCACAGAUGGUCC UGCACCCUmjUAUUGACCUCUCUGCUGAUC (Seq ID No 23).

Fragment D is shown below and is the complement of the sequence shown in bold in Fragment A.

Fragment D: CAGTTGAATAACCTGTGGGGGAACTTGCTTTGCCAAACCCATCCCTGCGG TTTCTGCCCAGGCTTGGGGAAACTGCTCCAACCAGGACTGTATATCTTGA TCAGGCrTTACITGGGGAGAATATAGTCGATATTCATCATCTAATTGGAG GGTCAACACAGTGATGGGTTTGTTATTCAC (Seq ID No 24) A folded Fragment D structure predicted by MFold shown below:

la fee above structure, bases 35rl71 form a significant hairpin structure. Bases 36-61 (AACCCATCCCTGCGGTTrCTGCCCAG (Seq ID Ho 25)) and bases 150-171 (GGGTCAACACAGTGATGGGTTT (Seq ID No 26)) were used to design a Drosha substrate with, a mir-29 loop and a mir-30 base. The mir-29 loop was chosen because of complementation between the base 36-61 fragment and the mir-30 loop. The MFold predicted structure of that substrate is;

The nucleotide sequence of the above sequence is GAUCUGCGCAACCCAUCCCUGCGGUUUCUGCCCAGUCAAUAUAAUUCUGGG UCAACACAGUGAUGGGUUUUGCUGAUC (Seq ID No 27).

In a similar manner, bases 86-107 (GACTGTATATCTTGATCAGGCT (Seq ID No 28))andbases 111-130 (CTTGGGGAGAATATAGTCGA (Seq ID No 29) were used to design a. Drosha substrate with a mir-30 loop and base. The MFold predicted structure of that substrate is;

The nucleotide sequence of the above sequence is GAUCUGCGCUGACUGUAUAUCUUGAUCAGGCCJG'UGAAGCCACAGAUGAGC UUGGGGAGAAUAUAGUCGAUGCUGAUC (Seq ID No 30).

Additional PERV Targeting Strategies: Targeting two mRNAs simultaneously;

The antisense strands of portions of two mRNAs were combined to create a single hairpin that targets two mRNAs.

The sequence below is a combined region of the complement of gag (italics) and the complement ofpol (underline). GQGTTGAGAgcagctggtagagtgaacgtgatccTCTCTGTGAGAAGCAGGCITTGATA r;rr7r?7rnr,TTCT^TAATACACCTTCTCTGCCTCTCTCACTagatcacgtaactcagcct r-rtot A A ncCTTGH AGTCTCTGAAGITrCTTTCTGATATCCAGAG (Seq ID No 31)

When the potential structure of this fragment is predicted by MFold, the following is produced.

To create a single hairpin with the potential to target both gag andpol, bases 100-123 (agatcacgtaactcagcctectgt (Seq ID No 33» and bases 10-34 (gcagctggtagagtgaacgtgatcc (Seq ID No 34» were used to design a Drosha substrate with a mir-30 base and loop and has the following MFold predicted structure.

The nucleotide sequence pf the above sequence is GAUOJGCGAGAUCACGUAACUCAGCCUCCUGUGUGAAGCCACAGAUGGCA GCUGGUAGAGUGAACGUGAUCCUGCUGAUC (Seq Π> No 32).

Additional PBRV Targeting Strategies: Use of Palindromic siRNAs

To reduce the effects of strand selection of siRNA efficacy» both strands of the hairpin can be designed to be identical or functionally identical. For example, the complement of pol (Fragment A) was analyzed using DNA Strider to identify potential palindromes, hi one such analysis (parameters: stringency 11, window 23), the following sequence was identified: TGGGCCmTAGCTGAGGCTCG (Seq ID No 36). TMs sequence was used to design a Drosha substrate with, mir-30 base and loop and bas the following MFold predicted structure:

The nucleotide sequence of the above sequence is GAUCUGCGCAUGGGCCUUUUAGCUGAGGCUCGUAGUGAAGCCACAGAUGU AUGGGCCUUUUAGCUGAGGCUCGUAUGCUGAUC (Seq ID No 37).

In a similar manner, another partial palindrome was identified, CTTCTGGTGCTCAGGAGCCCAGGAG (Seq ID No 38), used to design a Drosha substrate with rnir-3 0 base and loop, and has the following MFold predicted structure:

The nucleotide sequence pf the above sequence is GAUCUGCGAUUCUGGUGCUCAGGAGCCGAGGAGGUGAAGCCACAGAUGCU UCUGGUGCUCAGGAGCCCAGGAGUGCUGAUC (Seq ID No 39).

Likewise, another partial palindrome was identified, CATCGGTCTGGGGGCTGCCGGACGATG (Seq ID No 40), used to design a Drosha substrate with mir-30 base and loop, and has the following MFold predicted structure:

The nucleotide sequence of the above sequence is GAUCUGCGAAUCGGUCUGGGGGCUGCCGGACGAUGGUGAAGCCACAGAUG CAUCGGUCUGGGGGOJGCCGGACGAUGUGOJGAUC (Seq ID No 41).

ArtrKtirmal PKRV Targeting Strategies: Optimization of Hairpin formation,

Imperfect hairpins can result from using the above strategies. However, since non Watson/Crick base pairing is possible in RNA, the Drosha substrates can be modified without significant alteration in BNAi targeting. Below is a Drosha substrate designed to target a portion of PEEV env mRNA. Several “bubbles” are present in the stem, portion of the hairpin.

The nucleotide sequence pf the above sequence is GAUCUGCGAGAAACCACCCUUGAGUAGUUUCCGUGAAGCCACAGAUGGGA AACCACCCUUGAGUAGUUUCCUGCUGAUC (Seq ID No 42).

The “C” at position 15 was changed to “U”. The “U” can still base-pair with the “G” found in the target as the complement of “C”. However, the [TJ” can also base-pair with the “A” a position 65 in the hairpin. Similarly, the “C” at position IS was also changed to a “U" to base-pair with the “A” at position 62. The resulting predicted structure has an improved stem and is shown below.

The nucleotide sequence pf the above sequence is GAUCUGCGAGAAACUACUCUUGAGUAGUIKJCCGUGAAGCCACAGAUGGGA AACUACUCUUGAGUAGUUUCCUGCUGAUC (Seq ID No 43).

See also, ZengY, Cullen BR. Structural requirements for pre-microRNA binding nd nuclear export by Exportm 5. Nucleic Acids Res. 2004 Sep 08;32(16):4776-85; Zeng (, Cullen BR. Sequence requirements for micro SNA processing and function in human «11s. RNA. 2003 Jan;9(l):112-23; ZengY, Wagner EJ, Cullen BR. Both natural and lesigued micro RNAs can inhibit the expression of cognate mRNAs when expressed in luman cells. Mol Cell. 2002 Jun;9(6);1327-33; Boden D, Pusch O, Silbermann R, Lee F, rucker L, RamratnamB. Enhanced gene silencing of HTV-1 specific siRNA using ooicroRNA designed hairpins. Nucleic Adds Res. 2004 Feb 13;32(3);1154-8; Lee Y, Aim C, Han J, Choi H, Kim J, Yim J, Lee J, Provost P, Radmark O, Kim S, Kim VN. The nuclear RNase HI Drosha initiates raicroRNA processing. Nature. 2003 Sep25;425(6956):415-9; M. Zuker. Mfold web server for nudeic add folding and hybridization prediction. Nucleic Adds Res. 31 (13), 3406-15, (2003) [http ://www.bioinfo jpi. edu/ ^phcations/mfold/old/ma/forml .cgi].

Example 3: Sequential Cloning of Hairpin Oligonucleotides

To assemble oligos for clustered interference RNA, linker sequences must the considered to prevent unintentional structures from forming. If the same restriction sites are used sequentially, homologies at the base of the hairpin can cause unintentional base pairing. For example, if a vector is designed with two, non-compatible restriction sites a sequence can be cloned directionally into those two sites. In the process, the upstream site can be destroyed and also re-supplied to the new vector in the downstream region in preparation for the next hairpin.

Vector ends after being cut with Bell and MIuI:

MI MM

Overhang Overhang

NNNT3' 3'CGCGTNNN NNNACTAG 5’ 5ΆΝΝΝ

Hybridized Oligonucleotides: 5'GATCtgcgcTTAGATCCAGGGCTCATAATgtgaagccacagatgATTATGAGCCCTGGA TCTAATtgcTGATCActagtA 3' (Seq ID No 44) 3’acgcgAATCTAGGTCCCGAGTATTAcacttcggtgtctacTAATACrCGGGACCTAGAT TAacgACTAGTgatcaTGCGC 5’ (Seq ED No 45)

Resulting Clone:

Destroyed Supplied

Recreated

Bell Bell Mlul (italics) ' ('underlined'! (bold)

jVT0ATC%:gcTrA0ATCCAGGQCTCATAATg®aagccacagstgA.rrATGAGCCCTG0ATCTAATt8cTGAlCAetagtACGCGTN

MiCT^GaogcgAATCrAGGTGCCGAGTATTAcRcttcggtgtctacTAATACTCGGGACXrrAGATXAacgACIAGTgataaTGCXX^N (Seq ID No 46)

In this strategy, the oligonucleotide-supplied Bel I site can be used for the next cloning step and new oligonucleotides can continue to be added to each successive vector provided that none of the introduced stem sequences supply additional sites for either Bel IorMluL

Below is the resulting sequence of a series of three oligos cloned into a series of vectors using the strategy just described (vector, ottgo 1, oligo 2, oliso 51: .VZGATCtgcgcTXAGATCCAGGGCTCATAATgtgaagccacagatgATTATGAGCCC TGGATCTAATtgcTGATCtgcgcGGTAGAGACTTACTGACCAAgtgaagccacagatpTT GGTCAGTAAGTCTCTACCTtgcTG^TQgcgcA GAA CA TAGA GACCAA TGCAsteaae ccaeaeateTGCATTGGTCTCTATGTTCrrtecTGATCActaetACGCGTN(Seq ID No 47)

The predicted structure of this sequence follows. Each of the three hairpins are predicted to have the same general structure.

Using this strategy, any number of additional Drosha substrates can be added without alteration of their individual predicted structures.

Example 4: Synthetic Intron Assembly

An intron was designed, basal loosely on the intron found in the murine eosinophil-associated, ribonuclease A family genes (EarX) and a commercially available vector pCpG (IuvivoGen, San Diego, CA). The design of this intron included creation of restriction sites that allow of for placement of the inton into any Sbfl site within exon sequence. Upon splicing of primary transcripts containing this intron, the resulting mBNA is unaltered in comparison to its nan-engineered, endogenous counterpart. Si addition, a small series of cloning sites were included within the intron to allow subsequent cloning ofiSNA molecules/Drosha substrates. This sequence was cloned into an SMI site found naturally within the coding region of a dsRED expression vector (a red fluorescent protein from a corallimorpharian). Upon transfection into mammalian cells, tile resulting intron is appropriately spliced to yield functional dsRED protein.

Since the central six nucleotides of an SbfE site comprise a PstI site, this intron can also be cloned directly into PstI sites.

Intron sequence: (Sbf I sites shown bold, multiple cloning sites shown italics, functional intron underlined.) cctgcagGTAAGTCACTGCTGTCTATGCCTGGGAAAGGGGGGCAGGAGATGGGG CA&amp;TGCAGGAAAAGTGGCACTATGAACCCGtmteactaetacircetetacaATTGTACr AACCTTCTTCTCTTTCCTCTCCTGCAGg (Seq ID No 48)

Example 5 — Use of iRNA to reduce expression of contaminating proteins. Ια this example, expression of an endogenous protein is reduced to prevent or reduce contamination of a product of a trails gene. Transgenic animals are beginning to be used as sources for therapeutic proteins. These proteins are expressed from transgenes. The transgene expression can he targeted to specific tissues or cells types to provide compartmentalized harvesting of such proteins. For example, a protein can be concentrated in milk of transgenic animals by driving expression of said protean from a mammary specific promoter. In addition, a transgene may be selectively expressed in a specific cell type to allow for specific processing. For example, a human immunoglobulin locus can be used to direct recombination, expression, and processing of human polyclonal antibodies in livestock B-cells. In either of these cases, endogenous proteins can contaminate the material collected for purification. This protein may be evolutionarily unrelated but co-purifies with the desired product Alternatively, the contaminating protein may be the endogenous counterpart of the transgene product.

To provide guidance for the application of interfering RNA to reduce contaminating protein production in transgenic livestock, the following example is provided using immunoglobulin genes:

Sigpl.·.

The technique as described in Example 1, is used wherein the gag, pol and env genes described in Example 1 are replaced with genes for variable domains of porcine nnmunoglobulm (Ig), either variable or constant. In addition, Ig heavy-chain, Ig light chain kappa, and Ig light chain lambda are included as potential targets in the strategy.

Step 2:

The technique as described in Example 1 is used wherein Ihe analysis of PBRV targets is replaced by an analysis of Ig targets to determine the specificity of the iRNA constructs to the given target In addition to the test of .porcine Ig targets, potential targets that share homology with the human Ig transgene expressed in the animals are excluded.

Step 3:

Each selected iRNA construct is introduced into a porcine B-cell cell line. Down-regulation of Ig gene products is assayed by the methods described in Example 1. Specifically, mRNA is assessed by RT-PCR, and surface Ig is measured via labeled antibodies.

Steps 4 and 5:

Fetal fibroblasts axe contacted with the iRNA constructs identified in preceding steps. However, as fetal fibroblasts do not express Ig gene products, their utility in screening in this assay is limited, hi this case, late gestation fetuses are used to confirm iKNA effectiveness by RT-PCR and immunoassays. In a parallel set of experiments, fetal fibroblasts are engineered to expressed porcine Ig transgenes corresponding to the identified targets and iRNA constructs are tested for efficacy. Unintended targeting of human Ig is also assayed. Only iRNA constructs that do not target human Ig transgenes are used to produce fetuses.

Total mRNA is harvested from thymus, spleen, and blood of late gestation fetuses. This RNA is used to screen for endogenous Ig down-regulation by RT-PCR using primers specific to each Ig locus. Each assay includes additional control sequences to ensure that no errors are introduced.

Cells that contain human Ig transgenes are used to reconstruct embryos via nuclear transfer. These cells can be derived from screened fetuses, frozen and stored cell colonies, or cells used to produce the screened fetuses. Reconstructed embryos are used to produce transgenic offspring with the desired traits.

Confirmation of both down-regulation of endogenous porcine Ig gene products and expression of transgenic gene products (ie. human Ig) is confirmed. Animals are bled at various stages of maturity and analyzed for iKNA transgenc expression, Ig transgene expression, and endogenous Ig gene suppression. The procedure is also repeated under conditions eliciting various immunological states.

Example 6 - Use of interfering RNA to produce virus resistant animals. RNA interference technology is applied to produce animals that axe resistant to a virus and/or have reduced capacity to shed or propagate a virus. A transgene is constructed that results in expression of interfering RNA that targets one or more essential regions of Marek’s disease virus. The transgene construct is then added to the genome of chickens to produce a genetic line that heritably expresses SNA. hi this example, the genetic line heritably expresses two RNAs that hybridize to produce a dsKNA molecule, targeted to the essential regions of Marek’s disease virus. In a nondisease state the dsKNA is functionally inert, however, when a cell becomes infected with Marek’s disease virus, the dsKNA interferes with a viral gene, thus disrupting the viral life-cycle. Such chickens are therefore resistant to Marek’s disease.

To provide guidance in the application of interfering KNA to produce animals with enhanced resistance to a virus, the following is provided:

Method:

The technique as described in Example 1 is used wherein PERV is replaced by Marek’s disease virus. In addition, a cell that sheds Marek’s disease is used instead of PIC-15 cells. Furthermore, methods for the production of transgenic poultry, varying slightly from those described but known in the art, can be implemented. Embryonic chicks are used to confirm effectiveness. The appropriate integration site for the iRNA is identified by screening for iRNA expression in transgenic animals after they have reproduced. To this end, transgenic offspring are available for further propagation of appropriate lines.

Example 7 - Use of interfering BNA to reduce rejection of xenotransplanted organs.

Using the techniques described above, a transgene is constructed for expression of dsRNA that targets VC AM to suppress inflammation in xenotransplanted organs. To provide guidance in the application of interfering SNA to produce xenotransplantation pigs with enhanced organ survival, the following is provided;

Method:

The methods described in Examples 1 serve as a model for screening iSNA targets. In this embodiment, porcine VCAM is the target. A porcine cell line that expresses VCAM is used in place of PK-15 cells. A similar strategy as disclosed in Example 1, Step 2 and Figure 11 is employed to remove fRNA targets that are active against VCAM family members.

Example 8 - Use of Interfering UNA to reduce expression of an endogenous gene. SNA interference is used to suppress expression of an endogenous gene in a tissue specific manner. A transgene is assembled for expression of dsRNA which targets myostatin (GDF-8). In this example, the suppression of the target is intended to be incomplete. Mutations of myostatin provide increased muscle mass in livestock and mice, indicating that an economically beneficial phenotype could accompany a loss of function in myostatin. However, complete elimination of myostatin produces a phenotype that is not economically viable for meat production (Yang J, et al. (2001) Mol. Reprod. Dev. 60(3):351-61). Ihterfeimg ENA technology is used to produce animals suppressed expression of myostatin. Tissue specific expression of an flRNA molecule that provides less than complete suppression is provided by a tissue specific manner on a pol HI promoter.

Method:

The methods described in Example 1 serve as a model for screening iRNA targets. In this example, porcine GDF-8 is the target rather than PERV. A porcine cell line that expressed GDF-8 is used instead of PK-15 cells. The iRNA molecules identified, first by virtual sequence alignment and thereafter by in vitro screening are subject to efimination if they are not effective within the parameters identified. Therefore, unlike the previous examples, complete abolition of myostatin eliminates an iRNA molecule from consideration.

Example 9 - Use of Interfering RNA to provide resistance to viruses. SNA interference technology is applied to produce pigs that are resistant to viruses that are dangerous to patients undergoing xenotransplantation. hi xenotransplantation procedures, a risk exists that donor organs are a reservoir human, in addition to porcine, viruses. For example, one virus that poses a risk to a patient undergoing a xenotransplant is an influenza virus. Therefore, a transgene is constructed that results in the expression of interfering RNA that targets one or more essential regions of viruses that present risks to a patient receiving a xenotransplanted organ. The methods as described in Example 1 serve as a model for screening iRNA targets, hi this case, the influenza virus and its homologous provide the targets, instead of PERV. Instead of PK-15 cells, a cell that sheds influenza virus is used for screening. The iRNA constructs are screened for their capacity to fully inhibit influenza viral mRNA as well as viral particle production. When useful iRNA sequences are identified, they are linked within a vector to provide a transgenic construct that can completely eliminate the expression of the viral gene products. Further rounds of screening ensure that the most effective combination is identified. After screening, the constructs are introduced into fibroblasts to be used in nuclear transfer procedures, thus providing a transgenic cell line resistant to influenza virus.

Example 10 - Use of interfering RNA to provide genetic selection

Selectable markers are limiting in mammalian cells in that most marker genes provide antibiotic resistance and a finite number have been characterized. Therefore, siKNA transgeaes that provide a selectable phenotype can serve as selectable marker genes. The methods described in Example 1 serve as a model for screening IKNA targets. In this case, a cell that provides a selectable phenotype which a particular gene is downregulated is used. The iKNA constructs are screened for their capacity to produce the selecable phenotype. When useful lRNA construct are identified, drey can be linked to other genes or other DNA fragments to provide a selectable phenotype. Additionally, this strategy can be used to create combinations of genes that allow selection of homologous recombination events. As an example, a non-iRNA selectable marker gene is included between two targeting arms. Outside of these arms an anti-selectable marker iRNA transgene is placed. The lRNA transgene is identified as in above examples using the selectable marker gene as the target gene. Upon random integration, the iKNA transgene prevents function of the selectable marker ami the integration event is not selected. Upon homologous recombination, the iKNA transgene is not present and the selectable marker gene functions. Similarly and alternatively, the iKNA transgene can be directed against a gene essential to cell survival.

The invention described herein can be practiced in the absence of any element or elements, limitation or limitations which is not specifically disclosed herein. The terms and expressions that have been employed are used as terms of description and not of limitation, and there is no intention that in the use of such terms and expressions of excluding any equivalents of the features shown and described tar portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed herein, optional features, modification and variation of toe concepts herein disclosed can he resorted to by those skilled in toe art, and that such modifications and variations are considered to be within toe scope of this invention as defined by toe appended claims. 3h addition, where features or aspects of the invention are described in terms of Markush. groups, those skilled in toe art will recognize that toe invention is also thereby described in teams of any individual member or subgroup of members of the Markush group.

Claims (14)

1. CLAIMS:

   1. A method for producing a non-human transgenic cell, comprising: introducing into a cell a vector or vectors that produce at least two iRNA molecules that functionally eliminate the expression of porcine endogenous retrovirus (PERV) genes, wherein the at least two iRNA molecules target at least two different regions of the same gene, different genes or the same region of a gene.
2. 2. The method according to claim 1, wherein the at least two iRNA molecules are integrated into the same vector.
3. 3. The method according to claim 1 or 2, wherein said vector or vectors are integrated into the genome of the transgenic cell.
4. 4. The method according to any one of the preceding claims, wherein the at least two iRNA molecules target at least two different genes which are members of the same family of genes.
5. 5. The method according to any one of the preceding claims, wherein the method further comprises producing a non-human transgenic animal which heritably expresses the two or more iRNA molecules.
6. 6. The method according to claim 5, wherein the method comprises producing the animal via a method selected from: a. nuclear transfer; or b. genetically modifying totipotent non-human embryonic cells using a method according to any one of claims 1 to 4.
7. 7. The method according to claim 5 or 6, further comprising obtaining a cell, tissue or organ from the non-human transgenic animal.
8. 8. A transgenic non-human animal which heritably expresses two or more iRNA molecules, wherein the animal is produced by the method according to any one of claims 5 to 7.
9. 9. The transgenic non-human animal according to claim 8, wherein the transgenic nonhuman animal is a porcine animal.
10. 10. A cell, tissue or organ from a non-human transgenic animal according to claim 8 or 9.
11. 11. A method to functionally eliminate the expression of a target mRNA comprising administering at least two iRNA molecules, wherein the at least two iRNA molecules functionally eliminate the expression of porcine endogenous retrovirus (PERV) genes.
12. 12. The method according to claim 11, wherein the at least two iRNA molecules target at least two different regions of the same gene.
13. 13. The method according to claim 12, wherein the at least two iRNA molecules target at least two different genes which are members of the same family of genes.
14. 14. The method according to claim 11, wherein the at least two iRNA molecules target the same region of a gene.