WO2000039311A1

WO2000039311A1 - Human fibroblast growth factor receptor 1 is a co-receptor for infection by adeno-associated virus 2

Info

Publication number: WO2000039311A1
Application number: PCT/US1999/031220
Authority: WO
Inventors: Arun Srivastava; Keyun Qing; Cathryn Mah; Jonathan Hansen; Shangzhen Zhou; Varavani Dwarki
Original assignee: Advanced Research And Technology Institute
Priority date: 1998-12-31
Filing date: 1999-12-29
Publication date: 2000-07-06
Also published as: AU2596400A; JP2002533128A; CA2358094A1; EP1141339A1; EP1141339A4

Abstract

The present invention relates generally to the fields of gene therapy. More particularly, it concerns gene transfer using adeno-associated virus and methods of increasing transcription and promoting replication of transgenes. The present invention shows that AAV requires human fibroblast growth factor receptor 1 (FGFR1) as a co-receptor for successful viral entry into the host cell. Methods and compositions for exploiting this finding in AAV vector-mediated gene therapy are disclosed.

Description

DESCRIPTION

HUMAN FIBROBLAST GROWTH FACTOR RECEPTOR 1 IS A CO- RECEPTOR FOR INFECTION BY ADENO-ASSOCIATED VIRUS 2

BACKGROUND OF THE INVENTION

The present application claims the benefit of U.S. Provisional Patent

Application, Serial Number 60/114,596, filed December 31, 1998. The government may own rights in the present invention pursuant to Public Health Service grant numbers HL-48342, HL-53586, HL-58881, and DK-49218, from the National

Institutes of Health (Centers of Excellence in Molecular Hematology).

1. Field of the Invention

The present invention relates generally to the fields of gene therapy. More particularly, it concerns gene transfer using adeno-associated virus and methods of increasing transcription and promoting replication of transgenes.

2. Description of Related Art

Gene therapy protocols involving recombinant viral vectors are gaining wide attention as a new weapon against disease. Of the different viral vectors used for gene transfer, the retrovirus and adenovirus-based vector systems have been the most extensively investigated. Recently, adeno-associated virus (AAV) has emerged as a potential alternative to the more commonly used retroviral and adenoviral vectors (Muzyczka, 1992; Carter, 1992; Flotte and Carter, 1995; Chatterjee et al, 1995; Chatterjee and Wong, 1996). While studies with retroviral- and adenoviral-mediated gene transfer raise concerns over potential oncogenic properties of the former, and immunogenic problems associated with the latter, AAV has not been associated with any such pathological indications (Berns and Bohenzky, 1987; Berns and Giraud, 1996).

The viral genome of AAV is a single-stranded DNA of 4,680 nucleotides, flanked at both ends by 145 nucleotide-long palindromic inverted terminal repeats (ITRs) (Srivastava et al, 1983). Wild-type AAV has been shown to integrate into human chromosome in a site-specific manner (Kotin et al, 1991; Samulski et al, 1991), whereas recombinant AAV vectors appear not to integrate site-specifically (Kearns et al, 1996; Ponnazhagan et al, 1997). In previous studies, it has been documented that transduction efficiency of AAV vectors in permissive cells correlates well with the phosphorylation state of a cellular protein, designated the single- stranded D-sequence-binding protein (ssD-BP), which preferentially interacts with the D(-) sequence within the AAV ITR sequence (Qing et al, 1997; Qing et al, 1998; and U.S. Patent application serial number 09/145,379, specifically incorporated herein by reference in its entirety). Two independent groups have presented evidence suggesting that following infection, the rate-limiting step for the efficient transduction by AAV is the viral second-strand DNA synthesis (Fisher et al, 1996; Ferrari et al, 1996). Further, it has been demonstrated that the tyrosine phosphorylation state of the ssD-BP correlates well with the efficiency of AAV-mediated transgene expression in vivo as well (Qing et al, 1998).

AAV possesses a broad host-range that transcends the species barrier (Muzyczka, 1992). Recently, cell surface heparan sulfate proteoglycan (HSPG) was identified as a receptor for AAV (Summerford and Samulski, 1998). The ubiquitous expression of HSPG, perhaps, accounts for the broad host-range of AAV. However, it also has become increasingly clear that, for the most part, efficient viral infection of the host cell is accomplished in at least two steps: attachment and entry, presumably requiring at least two distinct cell surface macromolecules, a receptor and a co- receptor, respectively. A cogent example of such an event has been presented in the context of infection by the human immunodeficiency virus 1 (HIVl) which utilizes the cell surface CD4 antigen as a site of attachment followed by one of the chemokine receptors for the viral entry (Alkhatib et al, 1996; He et al, 1997). Similar scenarios also have emerged for efficient infection by adenovirus and herpesvirus (Laquerre et al, 1998; Bergelson et al, 1997; Montgomery et al, 1996; Geraghty et al, 1998).

Improving the efficiency of AAV infection will increase the use of this vector in gene therapy applications. However, to date the identity of a receptor that successfully mediates infection of cells by AAV has remained elusive. Once such a receptor or factor is elucidated, it will be possible to increase the efficiency of AAV-mediated gene therapy.

SUMMARY OF THE INVENTION

The present invention, for the first time, describes the co-receptor needed for AAV entry into a cell. In a particular embodiment of the present invention, there is described a method of increasing AAV infection of a cell comprising increasing the amount of fibroblast growth factor receptor (FGFR) on the surface of the cell, wherein the increased FGFR increases the AAV uptake by the cell. By increasing the amount of FGFR of said cell, the present invention refers to any method that effectively increases the number of accessible AAV binding sites on the surface of said cell. Thus it is envisioned that such sites may be made available through engineering steps or through the application of agents that allow for a change in protein confirmation such that the AAV-binding sites become exposed to the AAV being presented.

In specific embodiments, increasing the amount of FGFR on the cell may comprise providing to the cell an expression construct comprising a polynucleotide encoding an FGFR polypeptide and a promoter active in eukaryotic cells, the polynucleotide being operably linked to the promoter. In preferred embodiments, the FGFR polypeptide is selected from the group consisting of FGFRl, FGFR2, FGFR3 or FGFR4. In other preferred embodiments, it is contemplated that the method further comprises increasing the amount of cell surface heparan sulphate proteoglycan (HSPG) on the cell. In particular embodiments, increasing the HSPG of the cell comprises providing to the cell an expression construct comprising a polynucleotide that encodes an HSPG polypeptide and a promoter active in eukaryotic cells, the polynucleotide being operably linked to the promoter. In still other embodiments, it may be possible to increase the AAV binding capacity of the HSPG receptor by altering it conformation and/or glycosylation pattern. In certain embodiments, the method further may comprise contacting the cell with an AAV vector. In more particular embodiments, the AAV vector is a vector comprising an expression cassette comprising a selected polynucleotide and a promoter active in eukaryotic cells, wherein the polynucleotide is operably linked to the promoter. More specifically, it is contemplated that the selected polynucleotide encodes a polypeptide. In other embodiments, the selected polynucleotide may encode an antisense construct. In yet another alternative, the selected polynucleotide encodes a ribozyme. In defined embodiments, the promoter may be any promoter known to be useful in a particular gene delivery application. In certain embodiments, the promoter may be an inducible promoter. In certain preferred embodiments, the promoter is CMV LE, SV40 LE, HSV tk, β-actin, human globin α, human globin β, human globin γ, RSV, B19p6, alpha-1 antitrypsin, PGK, tetracyclin, MMTV or albumin promoter.

In specific embodiments, of the present invention, the expression cassette(s) further may comprise a polyadenylation signal. More particularly, the polyadenylation signal may be an AAV polyadenylation signal, an SV40 polyadenylation signal or a BGH polyadenylation signal. Of course these are merely exemplary polyadenylation signals, it is understood that those of skill in the art will be able to substitute other polyadenylation signals therefor and arrive at an expression cassette that may be used in the method of the present invention.

In specific embodiments, the selected polypeptide may be a hormone, a tumor suppressor, an inhibitor of apoptosis, a toxin, a lymphokine, a growth factor, an enzyme, a DNA binding protein or a single-chain antibody. In those embodiments in which the present invention provides a receptor encoding expression construct, the expression construct may be a viral vector. More particularly, the viral vector may be selected from the group consisting of retrovirus, adenovirus, vaccinia virus, herpesvirus and adeno-associated virus.

The present invention further provides a method of expressing a selected polynucleotide from an adeno-associated viral (AAV) vector in a host cell comprising the steps of providing an AAV vector comprising an expression cassette comprising the selected polynucleotide and a promoter active in eukaryotic cells, wherein the selected polynucleotide is operably linked to the promoter; contacting the vector with the host cell under conditions permitting uptake of the vector by the host cell; and increasing the amount of fibroblast growth factor receptor (FGFR) on the surface of said cell; wherein the increased FGFR increases the uptake of AAV by the cell. This increased uptake of AAV will thereby increase the level of transcription of the selected polynucleotide increased relative to the transcription of the selected polynucleotide in a cell where FGFR activity is not increased. Similarly, by providing the cell with an increased ability for AAV infectivity, the methods of the present invention will increase AAV-mediated transduction efficiency of a selected polynucleotide in a host cell.

In specific embodiments, the method of increasing FGFR on the surface of the cell comprises providing to the cell an expression construct comprising a polynucleotide encoding an FGFR polypeptide and a promoter active in eukaryotic cells, the polynucleotide being operably linked to the promoter. In preferred embodiments, the FGFR polypeptide is selected from the group consisting of FGFRl, FGFR2, FGFR3 or FGFR4. The method further may comprise increasing the amount of cell surface heparan sulphate proteoglycan (HSPG) in the cell. More particularly, increasing the HSPG of the cell comprises providing to the cell an expression construct comprising a polynucleotide that encodes an HSPG polypeptide and a promoter active in eukaryotic cells, the polynucleotide being operably linked to the promoter. In certain embodiments, the HSPG encoding polynucleotide and the FGFR encoding polynucleotide are in the same expression construct. In other embodiments, the HSPG encoding polynucleotide and the FGFR encoding polynucleotide are separated by an LRES. It is contemplated that the HSPG encoding polynucleotide and the FGFR encoding polynucleotide each may be under the control of a separate promoter operative in eukaryotic cells.

It is contemplated that the methods of the present invention may be carried out on any cell amenable to gene therapy and/or delivery manipulations. In particular embodiments, the host cell is an erythroid cell. In other defined embodiments, the erythroid cell is a human erythroid cell. In certain embodiments, the host cell may be selected from the group consisting of a bone marrow cell, a peripheral blood cell, a lung cell, a gastrointestinal cell, an endothelial cell and myocardial cell. In specific embodiments, the host cell is in an animal.

In particular embodiments, the method further may comprise inhibiting the function of D sequence binding protein (D-BP) in the host cell. More particularly, the inhibiting may comprise reducing the expression of D-BP in the host cell. In other embodiments, reducing the expression of D-BP may be achieved by contacting the host cell with an antisense D-BP polynucleotide. More particularly, the antisense D- BP polynucleotide may target a translational start site. In other embodiments, the antisense D-BP polynucleotide targets a splice-junction site. In certain embodiments, the agent that reduces the expression of D-BP is an antibody or a small molecule inhibitor. In specific embodiments, the antibody may be a single chain antibody or a monoclonal antibody. In other embodiments, the inhibiting comprise reducing the D sequence binding activity of the D-BP in the host cell. In specific embodiments, reducing the binding activity is achieved by inhibiting the tyrosine phosphorylation of D-BP. More particularly, inhibiting the phosphorylation is achieved by contacting the host cell with a D-BP peptide containing a tyrosine residue. In specific embodiments, inhibiting the phosphorylation is achieved by contacting the host cell with an agent that inhibits tyrosine kinase. In defined embodiments, the tyrosine kinase is an EGF- R tyrosine kinase. In specific embodiments, the agent is an inhibitor of EGF-R that reduces the expression of EGF-R protein kinase. In other embodiments, the inhibitor of EGF-R protein kinase is an agent that binds to and inactivates EGF-R protein kinase. In still further embodiments, the inhibitor of EGF-R protein kinase inhibits the interaction of EGF-R with a D-BP. In specific aspects, the agent that reduces the expression of EGF-R protein kinase is an antisense construct, in other aspects, the agent that binds to and inactivates EGF-R protein kinase is an antibody or a small molecule inhibitor. In particularly preferred embodiments, the agent may be selected from the group consisting of hydroxyurea, genistein, tyrphostin 1, tyrphostin 23, tyrphostin 63, tyrphostin 25, tyrphostin 46, and tyrphostin 47. Another aspect of the present invention provides a method for providing a therapeutic polypeptide to a cell comprising the steps of providing an AAV vector comprising an expression construct comprising the a polynucleotide that encodes the polypeptide and a promoter active in eukaryotic cells, wherein the polynucleotide is operably linked to the promoter; contacting the vector with the cell under conditions permitting uptake of the vector by the cell; and increasing the amount of fibroblast growth factor receptor (FGFR) on the surface of the cell; wherein the increase in FGFR results in an increase in the uptake of the vector by the cell. In preferred embodiments, the FGFR polypeptide is selected from the group consisting of FGFRl, FGFR2, FGFR3 or FGFR4. In particular embodiments, the therapeutic polypeptide is a hormone, a tumor suppressor, an inhibitor of apoptosis, a toxin, a lymphokine, a growth factor, an enzyme, a DNA binding protein or a single-chain antibody. In certain preferred embodiments, the cell is located within a mammal. In particular embodiments, the cell is a cancer cell. More particularly, the cell is selected from the group consisting of lung, breast, melanoma, colon, renal, testicular, ovarian, lung, prostate, hepatic, germ cancer, epithelial, prostate, head and neck, pancreatic cancer, glioblastoma, astrocytoma, oligodendroglioma, ependymomas, neurofibrosarcoma, meningia, liver, spleen, lymph node, small intestine, blood cells, colon, stomach, thyroid, endometrium, prostate, skin, esophagus, bone marrow and blood.

Thus in a broad sense the present invention provides a method for treating a disease in a subject comprising the steps of providing an AAV vector comprising an expression cassette comprising a therapeutic polynucleotide and a promoter active in eukaryotic cells, wherein the therapeutic polynucleotide is operably linked to the promoter; contacting the vector with the host cell under conditions permitting uptake of the vector by the host cell; and increasing the amount of FGFR on the surface of said cell; wherein the increase in FGFR on the cell surface increases the ability of said cell take up AAV. Thus the AAV is able to provide the therapeutic polynucleotide to a cell of said subject where the polynucleotide is transcribed and effects a treatment of the disease. The disease may be any disease that can be treated by the application of a polynucleotide e.g., cystic fibrosis, cancer, hyperproliferative disorders and the like. Also provided herein is an adenoassociated viral expression construct comprising: a first polynucleotide encoding a selected gene and a first promoter functional in eukaryotic cells wherein the polynucleotide is under transcriptional control of the first promoter; and a second polynucleotide encoding an FGFR. In preferred embodiments, the FGFR polypeptide is selected from the group consisting of FGFRl, FGFR2, FGFR3 or FGFR4. In specific embodiments, the expression construct further may comprise a third polynucleotide encoding an HSPG polypeptide. In preferred embodiments, the FGFR encoding polynucleotide is under the control of the first promoter. In other embodiments, the first polynucleotide and the second polynucleotide are separated by an IRES. In specific embodiments, the second polynucleotide is under the control of a second promoter operative in eukaryotic cells. In particularly preferred embodiments, the selected gene encodes a protein selected from the group consisting of a tumor suppressor, a cytokine, a receptor, inducer of apoptosis, and differentiating agents. In those embodiments in which the gene encodes a tumor suppressor, the tumor suppressor may selected from the group consisting of p53, pl6, p21, MMAC1, p73, zacl, C-CAM, BRCAI and Rb. In those embodiments in which the gene encodes an inducer of apoptosis, the inducer of apoptosis may be selected from the group consisting of Harakiri, Ad E1B and an ICE- CED3 protease. In those embodiments where the gene encodes a cytokine, the cytokine is selected from the group consisting of IL-2, LL-2, IL-3, IL-4, LL-5, LL-6, IL- 7, IL-8, IL-9, IL-10, IL-11, IL-12, LL-13, IL-14, IL-15, TNF, GMCSF, β-interferon and γ-interferon. In those embodiments, in which the gene encodes a receptor other that FGFR and HSPG, the receptor may be selected from the group consisting of CFTR, EGFR, VEGFR, IL-2 receptor and the estrogen receptor.

The present invention further contemplates a pharmaceutical composition comprising a first adenoassociated viral expression construct comprising a promoter functional in eukaryotic cells and a first polynucleotide encoding a selected polypeptide, wherein the first polynucleotide is under transcriptional control of the promoter; a second polynucleotide encoding an FGFR; and a pharmaceutically acceptable buffer, solvent or diluent. In specific embodiments, the composition further may comprise a second expression construct comprising a third polynucleotide encoding an HSPG polypeptide wherein the third polynucleotide operatively linked to a third promoter.

Other objects, features and advantages of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present invention. The invention may be better understood by reference to one or more of these drawings in combination with the detailed description of specific embodiments presented herein.

FIG. 1A-FIG. IE: Analysis of binding (FIG. IA) of wt AAV to different cell types, and comparative analyses of transduction efficiency (FIG. IB-FIG. IE) of the recombinant vCMVp-ZαcZ vector in HeLa and NLH3T3 cells. Equivalent numbers of human KB, HeLa, 293, M07e, and murine NLH3T3 cells were analyzed in binding

35 assays in triplicate using S-AAV as described in Methods. Approximately equivalent numbers of HeLa (FIG. IB and FIG. 1C) and NIH3T3 (FIG. ID and FIG. IE) cells were either mock-treated (FIG. IB and FIG. ID), or treated with 500 mM of tyrphostin 1 for 2 h (FIG. 1C and FIG. IE), and infected with 2xl0³ particles/cell of vCMVp-/αcZ under identical conditions. Forty eight hours post infection (p.i.), cells were fixed, stained with X-gal and photographed using a Nikon inverted light microscope. Magnification x 100.

FIG. 2A and FIG. 2B: Comparative analyses of binding of 1 ⁱ2^z5^;, _τI-bFGF (FIG. 2A) and ³⁵S-AAV (FIG. 2B) to M07e and Raji cells following either mock- transfection, or stable transfection with HSPG and/or FGFRl expression plasmids. Approximately equivalent numbers of cells were analyzed in triplicate as described in Example 1.

FIG. 3A-FIG. 3H: Analysis of transgene expression in M07e (FIG. 3A-FIG.

3D) and Raji (FIG. 3E-FIG. 3H) cells. Equivalent numbers of mock-transfected or stably transfected cells with the indicated expression plasmids were infected with 10⁴ particles/cell of the vCMVp-ZαcZ vector under identical conditions and analyzed by FACS 48 h p.i. as described in Methods. For each sample, lxlO⁴ cells were analyzed. The percentages of cells in the Ml region expressing the transgene are provided in Table 3.

FIG. 4A-FIG. 4F: Comparative analyses of transgene expression in M07e (FIG. 4A-FIG. 4C) and Raji (FIG. 4D-FIG. 4F) cells stably co-transfected with HSPG+FGFR1 expression plasmids in the presence of co-infection with adenovirus or with prior treatment with tyrphostin 1. Equivalent numbers cells were infected with 10⁴ particles/ml of the recombinant vCMVp-ZαcZ vector under identical conditions. Forty-eight hours post infection, cells were analyzed by FACS as described in the legend to FIG. 3. The data in FIG. 4A and FIG. 4D indicate mock-transduced cells. For each sample, lxlO⁴ cells were analyzed. The percentages of cells in the Ml region expressing the transgene are provided in Table 4.

FIG. 5A-FIG. 5H: Effect of bFGF and EGF on AAV binding to non- permissive (FIG. 5A) and permissive (FIG. 5B) cells, and on entry (FIG. 5C-FIG. 5H)

35 into permissive cells. S-AAV binding assays were carried out with equivalent numbers of NIH3T3 and 293 cells essentially as described in the legend to FIG. 1 except that large excess of either heparin (6 mg), bFGF (6 mg), EGF (6 mg), or unlabeled wtAAV (lxlO¹⁰ particles), were included in the reaction mixtures. Equivalent numbers of 293 cells also were used to infect with 2xl0³ particles/cell of the recombinant vCMVp-/αcZ vector with no treatment (a), with prior treatment with 150 mM genistein (b), in the presence of similar excess of bFGF (c), with prior treatment with 150 mM genistein and bFGF (d), in the presence of similar excess of EGF (e), or with prior treatment with 150 mM genistein and EGF (f). Cells were fixed, stained, and photographed as described in the legend to FIG. 1. Magnification x 40.

FIG. 6A-FIG. 6B: A model for the role of cell surface HSPG and FGFRl in mediating AAV binding and entry into the host cell. Co-expression of HSPG and

FGFRl is required for successful binding of AAV followed by viral entry into a susceptible cell (FIG. 6A), both of which are perturbed by the ligand, bFGF, which also requires the HSPG-FGFR1 interaction (FIG. 6B).

FIG. 7: AAV co-receptor activity of FGFRl, FGFR2, FGFR3, and FGFR4. These assays were performed as described in Example 1.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The use of viral vectors in a variety of gene transfer endeavors now is widely accepted. For example, retroviral vectors have been used for a number of years to transform cell lines in vitro for the purpose of expressing exogenous polypeptides. More recently, with advancements in genetic therapies, various other vectors including adenoviruses and herpes viruses, along with retroviruses, and more recently adeno-associated viruses, have been utilized to transfer therapeutic genes into cells.

While retroviral vectors and adenoviral vectors have been associated with a wide variety of pathological indications, adeno-associated viral (AAV) vectors are considered especially desirable for a number of reasons. In the first instance, AAVs are not associated with any known pathological indications. Further, AAV can infect non-dividing cells (Kotin et al, 1990; Kotin et al, 1991; Samulski et al, 1991) and also possesses anti-oncogenic properties (Berns and Giraud, 1996). Recombinant AAV vectors can be produced that lack any of the coding sequences of wild-type AAV, yet retain the property of stable chromosomal integration and expression of the recombinant genes upon transduction both in vitro and in vivo (Bertran et al, 1996; Kearns et al, 1996; Ponnazhagan et al, 1997a).

Despite the fact that AAVs clearly are an attractive alternative to other viral vectors, the use AAV as a delivery vector has been limited. The efficiency of AAV infection of cells is low even though AAV possesses a broad host-range that transcends inter- species barriers (Muzyczka, 1992). One factor suggested to explain the broad host range is that the cell surface heparan sulfate proteoglycan (HSPG) may be a receptor for AAV (Summerford and Samulski, 1998). However, the inventors' recent studies have documented a significant donor variation in terms of the ability of AAV vectors to transduce primary human bone marrow-derived CD34⁺ hematopoietic progenitor cells (Ponnazhagan et al, 1997). It was demonstrated that AAV failed to bind to CD34⁺ cells from approximately 50% of normal volunteer donors. Nonetheless, the lack of virus binding to cells was insufficient to account for the inability of AAV to infect cells. For example, in our preliminary experiments we noted that murine NIH3T3 cells could bind the virus efficiently, but could not be transduced by AAV. Thus, the inventors set out to look for a putative cell surface co- receptor for efficient infection by AAV. The present invention is directed to the elucidation of a co-receptor for infection by AAV. Methods and compositions relating to this finding are described in further detail herein below.

A. The Present Invention

Although the cell surface heparan sulfate proteoglycan (HSPG) has been identified as the putative receptor for AAV infection (Summerford and Samulski, 1998), it seems that the transduction efficiency of AAV vectors varies greatly in different cells and tissues in vitro and in vivo. However, in summarizing their findings, Summerford and Samulski, stated that HSPG is only initial attachment receptor for AAV-2, and that it is possible that AAV attachment and infection can also be mediated by an as yet unidentified receptor. Furthermore they suggested that their studies were able to show the HSPG is required for AAV infection but were not able to show whether HSPG is sufficient for infection. The present inventors have conclusively shown that cells which express the HSPG receptor alone are unable to be infected by AAV. The inventors reasoned that although HSPG may be responsible for AAV binding to cells, AAV entry into the cells is mediated by another receptor.

The present invention shows that cell surface expression of HSPG alone is insufficient for AAV infection, and that AAV also requires human fibroblast growth factor receptor (FGFR) as a co-receptor for successful viral entry into the host cell. The inventors document that cells that do not express either HSPG or FGFR fail to bind AAV, and consequently, are resistant to infection by AAV. These non- permissive cells are successfully transduced by AAV vectors following stable transfections with cDNAs encoding the murine HSPG and the human FGFR. Furthermore, AAV infection of permissive cells, known to express both FGFR and the epidermal growth factor receptor (EGFR), is abrogated by treatment of cells with basic fibroblast growth factor (bFGF), but not with epidermal growth factor (EGF).

Briefly, the present inventors were able to demonstrate that two non- permissive human cells, M07e and Raji, can be transduced with AAV following introduction of two genes: murine HSPG and human FGFRl. It was interesting to note that with Raji cells, expression of either the HSPG or the FGFR gene was insufficient to permit AAV binding and entry. In M07e cells, on the other hand, introduction of the HSPG gene was sufficient to allow AAV to bind and enter these cells. Upon closer examination, it was noted that M07e cells express an endogenous FGFR gene. Thus, successful AAV binding and subsequent entry requires co- expression of both HSPG and FGFR, much the same way as the FGF ligand (Rapraeger et l, 1991, Ledoux et al, 1992, Roghani and Moscatelli, 1992, Givol and Yayon, 1992, Kan et al, 1993). Interestingly, however, despite similar levels of co- expression of HSPG and FGFRl in M07e and Raji cells, as determined by the bFGF binding, the AAV transduction efficiency in the two cell types was significantly different. Further, AAV binding to the two cell types also was roughly the same, but the extent of viral DNA entry correlated well with the transduction efficiency in the two cell types. It remains possible, therefore, that other cellular factors are required for high-efficiency infection by AAV (Mah et al, 1998). It is known that NLH3T3 cells express both the endogenous HSPG and the FGFR genes, and that AAV could indeed bind to the muHSPG-muFGFR complex. Since AAV failed to gain entry into these cells, it would seem reasonable to suggest that the specificity of viral entry lies with the huFGFR. Two additional sets of data corroborate this contention. First, the muHSPG gene is functional in human cells, and second, huFGF abrogates AAV binding as well as entry into otherwise permissive human cells. EGF, on the other hand, has no effect on either AAV binding or entry into 293 cells which express high numbers of EGFR (Mah et al, 1998). Thus, the lack of effect of EGF on AAV-mediated transduction of 293 cells is not due to the absence of EGFR in these cells. HuFGF, which can bind to muFGFR, also is able to block AAV binding to NLH3T3 cells. Additional studies carried out with NIH3T3 cells stably transfected with the huFGFR 1 expression plasmid resulted in an increase in AAV transduction efficiency, albeit at low-levels, most likely due either to suboptimal cell surface expression of the human protein, or some form of steric hindrance with the murine counterpart. Based on all the available information, we propose a model for AAV infection, which is depicted in FIG. 6. In this model, co- expression of cell surface HSPG and FGFRl is required for successful AAV binding followed by viral entry (FIG. 6A), both of which are blocked by bFGF (FIG. 6B).

Given these findings, it now is possible to envision the improved use of AAV vectors in human gene therapy. For example, ensuring that the cells about to receive AAV mediated gene therapy express FGFR and HSPG will ensure an efficient binding and uptake of the AAV and will thereby increase the effectiveness of the therapy being applied. Methods and compositions for achieving such improved gene therapy are described in greater detail herein below.

B. Receptors for AAV infection

The inventors have identified a co-receptor responsible for efficient AAV infection. Recently, HSPG was identified as a putative receptor for AAV (Summerford and Samulski, 1998). However, it is clear that efficient viral infection of the host cell by AAV is accomplished in at least two steps— attachment and entry— presumably requiring at least two distinct cell surface macromolecules, a receptor and a co-receptor, respectively. The present inventors have identified FGFR as the essential co-receptor necessary for AAV infection. These two receptors and their roles in AAV infection are discussed in further detail herein below.

Although it was recently suggested that HSPG is a receptor for AAV infection, murine N1H3T3 which are know to express HSPG, failed to be infected by AAV as discussed above. The present invention describes the putative co-receptor for AAV infection. The present inventors investigations, described in the example, revealed that this co-receptor is FGFR (Rapraeger et al, 1991; Ledoux et al, 1992; Roghani and Moscatelli, 1992; Givol and Yayon, 1992; Kan et al, 1993). The present invention describes a model for AAV infection (FIG. 6). In this model, co-expression of cell surface HSPG and FGFRl is required for successful AAV binding followed by viral entry (FIG. 6A), both of which are blocked by bFGF (FIG. 6B).

a. FGF Receptors

Fibroblast growth factors (FGFs) regulate a diverse range of physic logic processes such as cell growth and differentiation and pathologic processes involving angiogenesis, wound healing and cancer (Basilico and Moscatelli, 1992). FGFs utilize a receptor system to activate signal transduction pathways (Klagsbrun and Baird, 1991; Ornitz et al, 1992; Yayon et al, 1991; Rapraeger et al, 1991). The primary component of this system is a family of signal-transducing FGF receptors (FGFRs). FGFRs are typical of polypeptide growth factor receptors. These receptors usually have three major identifiable regions. The first is an extracellular region which contains the domain that binds the polypeptide growth factor (i.e. the ligand- binding domain). The second region is a transmembrane region and the third is an intracellular region. Many of these receptors contain a tyrosine kinase domain in the intracellular region. It is contemplated that according to the present invention, FGFR family members may act as co-receptors for AAV infection.

The FGFRs contain an extracellular ligand-binding domain and an intracellular tyrosine kinase domain (Basilico and Moscatelli, 1992). The second component of this receptor system consists of heparan sulfate (HS) proteoglycans or related heparin-like molecules which are required in order for FGF to bind to and activate the FGFR (Ornitz et al, 1992; Yayon et al, 1991). Although the mechanism by which heparin/HS activates FGF is unknown, heparin, FGF and the FGFR can form a trimolecular complex (Ornitz et al, 1992). Heparin/HS may interact directly with the FGFR linking it to FGF (Kan et al, 1993). Furthermore, heparin/HS can facilitate the oligomerization of two or more FGF molecules, which may be important for receptor dimerization and activation (Ornitz et al, 1992).

Heparin/HS is a heterogeneously sulfated glycosaminoglycan that consists of a repeating disaccharide unit of hexuronic acid and D-glucosamine. It has been previously reported that, at a minimum, highly sulfated octa- (Ornitz et al, 1992) or decasaccharide (Ishihara et al, 1993) fragments derived from heparin are required for

FGF to bind to the FGFR.

The fibroblast growth factor receptor (FGF-R) proteins bind to a family of related growth factor ligands, the fibroblast growth factor (FGF) family. This family of growth factors are characterized by amino acid sequence homology, heparin- binding avidity, the ability to promote angiogenesis and mitogenic activity toward cells of epithelial, mesenchymal and neural origin.

The FGF family includes acidic FGF (aFGF) and basic FGF (bFGF) (Gospodarowicz et al, 1986); the int-2 gene product (Moore et al, 1986); the hst gene product or Kaposi's sarcoma FGF (Anderson et al, 1988; Taira et al, 1987); FGF-5 (Zhan et al, 1988); and keratinocyte growth factor (Rubin et al, 1989), and FGF-6 (I. Maries, et al, 1989). The actions of these FGFs are mediated through binding to specific high affinity cell surface receptors of approximately 145 and 125 kDa (Neufeld and Gospodarowicz, 1986; U.S. Patent 5,733,893 ). U.S. Patents 5,707,632; 5,229,501 and 5,783,683 (each specifically incorporated herein by reference) describe methods and compositions relating to the identification and purification of various fibroblast growth factor (FGF) receptors. Although FGFRs have been shown to be expressed in every organ and tissue examined (Givol and Yayon, 1992), the relative abundance of their expression in skeletal muscle and in neuroblasts and glioblasts in the brain correlates particularly well with the documented high efficiency of AAV-mediated transduction in these tissues in vivo (Qing et al, 1998). Since there are at least four distinct but related members in the FGFR family -FGFRl (Genbank Accession Nos. PI 1362; U23445; U22324, each specifically incorporated herein by reference), FGFR2 (Genbank Accession Nos. P21802; L49241; L49240; L49239; L4923, each specifically incorporated herein by reference), FGFR3 (Genbank Accession Nos. P22607; AF055074; Q61851, each specifically incorporated herein by reference), and FGFR4 (Genbank Accession Nos. AF031695; Q03142; P22455, each specifically incorporated herein by reference) — it is likely that these individual members may be useful alone or in combination with each other in facilitating successful infection by AAV (Rapraeger et al, 1991, Ledoux et al, 1992, Roghani and Moscatelli, 1992, Givol and Yayon, 1992, Kan et al, 1993, Lee et al, 1989).

Four genes encode the four forms of FGFR 1-4, which have a common structure composed of two or three extracellular immunoglobulin (Ig)-like loops (Igl- IgLn) and one intracellular tyrosine kinase domain. For FGFR 1-3, alternative splicing of the exon encoding the extracellular region produces multiple receptor forms (Johnson et al, 1991 Givol and Yayon, 1992). The genomic organization of the third Ig-like loop leads to three receptor variants. Two membrane-spanning forms are produced by alternative splicing of two exons (IJIb and Hie) encoding the second half of loop Lπ, whereas a selective polyadenylation site preceding exons LTIb and Hie is used to produce a soluble form of FGFRl (LTIa). In humans and mice, the mRNA transcript of the IgUJa splice variant of FGFRl encodes a protein that potentially has no hydrophobic membrane-spanning domain and may therefore be a secreted form of the receptor (SR) (Werner et al, 1992). Those of skill in the art are referred to Guillonneau et al, (1998, specifically incorporated herein by reference), which provides a comprehensive discussion about the various FGFR isoforms. b. HSPG Receptors

It is well documented that heparan sulphate proteoglycans (HSPGs) play important biological roles in cell-matrix adhesion processes and are essential regulators (or receptors) of growth factor actions. Proteoglycans are proteins classified by a posttranslational attachment of polysaccharide glycosaminoglycan (GAG) moieties each comprised of repeating disaccharide units (for reviews see references Jackson et al, 1991; Kjellen and Lindahl, 1991). They can be found associated with both the extracellular matrix and plasma membranes.

The four main, widely distributed, membrane-associated GAGs include heparin/HS and chondroitin sulfates A through C. These unbranched sulfated GAGs are defined by the repeating disaccharide units that comprise their chains, by their specific sites of sulfation, and by their susceptibility to bacterial enzymes known to cleave distinct GAG linkages (Linhardt et al, 1986). All have various degrees of sulfation which result in a high density of negative charge. Proteoglycans can be modified by more than one type of GAG and have a diversity of functions, including roles in cellular adhesion, differentiation, and growth. In addition, cell surface proteoglycans are known to act as cellular receptors for some bacteria and several animal viruses (Rostand and Esko, 1997), including; foot-and-mouth disease type O virus (Jackson et al, 1996), HSV types 1 and 2 (Sheih et al, 1992; WuDunn and Spear, 1989) and dengue virus (Chen et al, 1997).

Summerford and Samulski (1998) recently showed that HSPGs serve as a principal attachment receptor for AAV type 2 (AAV-2). Further, their results indicate that the presence of HS GAG on the cell surface directly correlates with the efficiency by which AAV can infect cells. Several observations led Samulski and Summerford to postulate that AAV-2 may use cell surface proteoglycans as a receptor. First, they demonstrated that AAV-2 binds to a cellufine sulfate column. Other viruses known to interact with such columns bind to negatively charged surface molecules (for example, several members of the Herpesviridae family known to use HS proteoglycans as attachment receptors Compton et al, 1993; Mettenleiter et al, 1990; Sheih et al, 1992; WuDunn and Spear, 1989). Second, AAV can infect a wide variety of human, rodent, and simian cell lines suggesting that it uses a ubiquitous cell surface molecule for infection (Muzyczka, 1992; Berns, 1996). One such family of ubiquitous receptors is the proteoglycans family (Diertrich and Cassaro, 1977; Kjellen and Lindahl, 1991). Despite these correlations, Samulski and Summerford (1998) concluded that although HS proteoglycans are required for AAV infection their studies did not address whether they are in fact sufficient. The present inventors have shown that while HSPG mediate the binding of AAV to the cell surface, they are incapable of mediating AAV entry into the cell. The present inventors, for the first time, show that efficient AAV mediated gene transfer requiremes FGFR as a co-receptor

C. Adeno-associated Virus and it use in Gene Therapy

Adeno-associated virus 2 (AAV)-based vectors have gained attention as a useful alternative to the more commonly used retroviral and adenoviral vectors for human gene therapy. Although AAV utilizes the ubiquitously expressed cell surface heparan sulfate proteoglycan (HSPG) as a receptor, the transduction efficiency of AAV vectors varies greatly in different cells and tissues in vitro and in vivo. The present invention shows that cell surface expression of HSPG alone is insufficient for AAV infection, and that AAV also requires human fibroblast growth factor receptor 1 (FGFRl) as a co-receptor for successful viral entry into the host cell. The identification of FGFRl as a co-receptor for AAV provides new insights not only into its role in the life cycle of AAV, but also in the optimal use of AAV vectors in human gene therapy. The present section provides a discussion of the uses of AAV in gene therapy applications.

a. Adeno-associated Virus

AAV utilizes a linear, single-stranded DNA of about 4700 base pairs. Inverted terminal repeats flank the genome. Two genes are present within the genome, giving rise to a number of distinct gene products. The first, the cap gene, produces three different virion proteins (VP), designated VP-1, VP-2 and VP-3. The second, the rep gene, encodes four non-structural proteins (NS). One or more of these rep gene products is responsible for transactivating AAV transcription. The sequence of AAV is provided in (Srivastava et al, 1983). The AAV-ITRs also contain an additional domain, designated the D-sequence, a stretch of 20 nucleotides that is not involved in the HP formation (Berns and Bohenzky, 1987; Berns and Giraud, 1996; Srivastava et al, 1983), the inventors hypothesize that one or more cellular protein(s) interact with the D-sequence and prevent the second strand viral DNA synthesis. Thus, the identification of such a host protein merits study. Once elucidated, it will be possible to increase the transcription and replication from an adeno-associated viral (AAV) vector. Other uses for such a protein will become apparent in the following disclosure.

The three promoters in AAV are designated by their location, in map units, in the genome. These are, from left to right, p5, pl9 and p40. Transcription gives rise to six transcripts, two initiated at each of three promoters, with one of each pair being spliced. The splice site, derived from map units 42-46, is the same for each transcript. The four non-structural proteins apparently are derived from the longer of the transcripts, and three virion proteins all arise from the smallest transcript.

AAV is not associated with any pathologic state in humans. Interestingly, for efficient replication, AAV requires "helping" functions from viruses such as herpes simplex virus I and LI, cytomegalo virus, pseudorabiesvirus and, of course, adenovirus. The best characterized of the helpers is adenovirus, and many "early" functions for this virus have been shown to assist with AAV replication. Low level expression of AAV rep proteins is believed to hold AAV structural expression in check, and helper virus infection is thought to remove this block.

The terminal repeats of the AAV vector of the present invention can be obtained by restriction endonuclease digestion of AAV or a plasmid such as p201, which contains a modified AAV genome (Samulski et al, 1987), or by other methods known to the skilled artisan, including but not limited to chemical or enzymatic synthesis of the terminal repeats based upon the published sequence of AAV. The ordinarily skilled artisan can determine, by well-known methods such as deletion analysis, the minimum sequence or part of the AAV JTRs which is required to allow function, i.e. stable and site-specific integration. The ordinarily skilled artisan also can determine which minor modifications of the sequence can be tolerated while maintaining the ability of the terminal repeats to direct stable, site-specific integration.

b. Adeno- Associated Virus Mediated Gene Therapy

AAV-based vectors have proven to be safe and effective vehicle for gene delivery in vitro, and these vectors are now being developed and tested in pre-clinical and clinical stages for a wide range of applications in potential gene therapy, both ex vivo and in vivo. However, the inventors (Ponnazhagan et al, 1997b; 1997c; 1997d; 1997d) and others (Carter and Flotte, 1996 ; Chatterjee et al, 1995; Ferrari et al, 1996; Fisher et al, 1996; Flotte et al, 1993; Goodman et al, 1994; Kaplitt et al, 1994; 1996, Kessler et al, 1996; Koeberl et al, 1997; Mizukami et al, 1996; Xiao et al, 1996) have repeatedly observed wide variations in AAV transduction efficiency in different cells and tissues in vitro as well as in vivo.

It would seem reasonable to suggest that AAV transduction efficiency correlates with the number of the putative cell surface receptors, although the identity of this receptor still remains elusive (Mizukami et al, 1996). However, it has become clear from the inventors' present studies that such a correlation most probably does not exist since 293 cells that express relatively the least numbers of these putative receptors are transduced most efficiently, an observation consistent with previously published reports (Ferrari et al, 1996; Fisher et al, 1996).

AAV-mediated efficient gene transfer and expression in the lung already has led to clinical trials for the treatment of cystic fibrosis (Carter and Flotte, 1996; Flotte et al, 1993). Similarly, the prospects for treatment of muscular dystrophy by AAV- mediated gene delivery of the dystrophin gene to skeletal muscle, of Parkinson's disease by tyrosine hydroxylase gene delivery to the brain, of hemophilia B by Factor DC gene delivery to the liver, and potentially of myocardial infarction by vascular endothelial growth factor gene to the heart, appear promising since AAV-mediated transgene expression in these organs has recently been shown to be highly efficient (Fisher et al, 1996; Flotte et al, 1993; Kaplitt et al, 1994; 1996; Koeberl et al, 1997; McCown et al, 1996; Ping et al, 1996; Xiao et al, 1996). Since the present invention shows that high efficiency of recombinant AAV transduction in these organs or tissues requires the presence of an FGFR co-receptor along with the presence of HSPG, any AAV-mediated gene therapy approach will be improved by ensuring the presence of these receptors on the target cells. If such receptors are not endogenously expressed they can be engineered into the target cells/organs thereby ensuring an efficient binding and uptake of the AAV vector.

D. Additional Factors Involved in Efficient AAV-mediated Gene Transfer Another aspect of the present invention involves increasing AAV-mediated transgene expression by manipulating post-receptor entry cellular events. More particularly, the examples of the present invention corroborate the inventors earlier findings that dephosphorylation of the ssD-BP is necessary to allow AAV-mediated transgene expression and AAV transduction efficiency.

Dephosphorylation of the D-BP facilitates second-strand synthesis of the AAV genome delivered to target cells as a single-stranded DNA molecule, suggesting that manipulation of phosphorylation state of this protein may be exploitable as one of the strategies for significantly improving transduction efficiency of recombinant AAV vectors. A strong correlation between phosphorylation state of the D-BP and the extent of efficient transduction by AAV in murine organs/tissues in vivo has also been demonstrated, showing this approach of improving transduction efficiency will work, as well as indicating that the D-BP may be evolutionarily conserved.

The mechanism by which dephosphorylation of the D-BP facilitates second- strand viral DNA synthesis remains unclear. One of the possibilities that the D-BP itself may possess a DNA polymerase-like activity currently is being tested. Alternatively, dephosphorylation of the D-BP might activate cellular DNA polymerase(s) necessary for host cell DNA synthesis or DNA-repair pathway, by which the second-strand viral DNA synthesis is accomplished. The inventors' studies with highly purified preparations of the D-BP indicate that this protein undergoes auto-phosphorylation followed by auto-dephosphorylation, the significance of which is not clear. However, the purified D-BP has been determined to be an approximately 53 kDa protein, but distinct from the p53 tumor suppressor protein, since monoclonal anti-p53 antibody failed to immunoprecipitate the D-BP.

Since the present invention shows that high efficiency of recombinant AAV transduction in a variety of organs is most likely due to the presence of dephosphorylated form of the D-BP, such an approach also will be useful in determining the transduction potential of untested tissues/organs, especially of human origin, by AAV vectors. For example, based on the data shown in Table 4, it would appear that kidney might be an additional organ of choice for AAV-mediated transduction since the ratio of dephosphorylated phosphorylated D-BPs in these tissues is approximately 1.4, a level consistent with that seen in 293 cells, a cell line derived from human embryonic kidney.

In another aspect, the search for additional specific compounds that mediate dephosphorylation of the D-BP is facilitated by the present invention. The elucidation of such compounds will serve to augment transduction efficiency of recombinant AAV vectors in a wide variety of tissue and organs, including primary hematopoietic stem/progenitor cells, potentially leading to their successful use in gene therapy of specific hematological disorders such as sickle-cell anemia and β-thalassemia (Goodman et al, 1994; Ponnazhagan et al, 1997d; Walsh et al, 1994; Zhou et al, 1996). Examples of mediators of phosphorylation known to those of skill in the art include genistein, tyrphostin A48, tyrphostin 1, tyrphostin 23, tyrphostin 25, tyrphostin 46, tyrphostin 47, tyrphostin 51, tyrphostin 63, tyrphostin AG 1478, herbmycin A, LY 294002, wortmannin, staurosporine, tyrphostin AG 126, tyrphostin AG 1288, tyrphostin 1295, and tyrphostin 1296. It is contemplated that the tyrphostins group of inhibitors will be particularly useful in conjunction with the present invention.

Previously, the inventors further documented that treatment of cells with specific inhibitors of the epidermal growth factor receptor protein tyrosine kinase (EGF-R PTK) activity, such as tyrphostin, leads to significant augmentation of AAV transduction efficiency, and phosphorylation of the ssD-BP is mediated by the EGF-R PTK (U.S. Serial Number 09/145,379, specifically incorporated herein by reference in its entirety). Treatment of cells with epidermal growth factor (EGF) results in phosphorylation of the ssD-BP, whereas treatment with tyrphostin causes dephosphorylation of the ssD-BP, and consequently, leads to increased expression of the transgene. Furthermore, AAV transduction efficiency inversely correlates with expression of the EGF-R in different cell types, and stable transfection of the EGF-R cDNA causes phosphorylation of the ssD-BP leading to significant inhibition in AAV- mediated transgene expression which can be overcome by the tyrphostin treatment.

E. Gene Transfer and Expression a. Regulatory Elements

In describing both the AAV vector, which contains the transgene of interest, and any FGFR or HSPG receptor containing construct for the purpose of expressing a protein, it should be noted that promoters will be required to drive the transcription of these genes. The nucleic acid encoding a gene product is under transcriptional control of a promoter. A "promoter" refers to a DNA sequence recognized by the synthetic machinery of the cell, or introduced synthetic machinery, required to initiate the specific transcription of a gene. The phrases "under transcriptional control" or "operably linked" mean that the promoter is in the correct location and orientation in relation to the nucleic acid to control RNA polymerase initiation and expression of the gene.

Within certain embodiments, expression vectors are employed to express the receptor polypeptide for use in conjunction with AAV mediated gene therapy. Expression requires that appropriate signals be provided in the vectors, and which include various regulatory elements, such as enhancers/promoters from both viral and mammalian sources that drive expression of the genes of interest in host cells. Elements designed to optimize messenger RNA stability and translatability in host cells also are defined. The conditions for the use of a number of dominant drug selection markers for establishing permanent, stable cell clones expressing the products also are provided, as is an element that links expression of the drug selection markers to expression of the polypeptide.

Throughout this application, the term "expression construct" is meant to include any type of genetic construct containing a nucleic acid coding for a gene product in which part or all of the nucleic acid encoding sequence is capable of being transcribed. The transcript may be translated into a protein, but it need not be. In certain embodiments, expression includes both transcription of a gene and translation of mRNA into a gene product. In other embodiments, expression only includes transcription of the nucleic acid encoding a gene of interest.

The term promoter will be used here to refer to a group of transcriptional control modules that are clustered around the initiation site for RNA polymerase LI. Much of the thinking about how promoters are organized derives from analyses of several viral promoters, including those for the HSV thymidine kinase (tk) and SV40 early transcription units. These studies, augmented by more recent work, have shown that promoters are composed of discrete functional modules, each consisting of approximately 7-20 bp of DNA, and containing one or more recognition sites for transcriptional activator or repressor proteins.

At least one module in each promoter functions to position the start site for RNA synthesis. The best known example of this is the TATA box, but in some promoters lacking a TATA box, such as the promoter for the mammalian terminal deoxynucleotidyl transferase gene and the promoter for the SV40 late genes, a discrete element overlying the start site itself helps to fix the place of initiation.

Additional promoter elements regulate the frequency of transcriptional initiation. Typically, these are located in the region 30-110 bp upstream of the start site, although a number of promoters have recently been shown to contain functional elements downstream of the start site as well. The spacing between promoter elements frequently is flexible, so that promoter function is preserved when elements are inverted or moved relative to one another. In the tk promoter, the spacing between promoter elements can be increased to 50 bp apart before activity begins to decline. Depending on the promoter, it appears that individual elements can function either cooperatively or independently to activate transcription.

The particular promoter employed to control the expression of a nucleic acid sequence of interest is not believed to be important, so long as it is capable of direction the expression of the nucleic acid in the targeted cell. Thus, where a human cell is targeted, it is preferable to position the nucleic acid coding region adjacent to and under the control of a promoter that is capable of being expressed in a human cell. Generally speaking, such a promoter might include either a human or viral promoter.

In various embodiments, the human cytomegalovirus (CMV) immediate early gene promoter, the SV40 early promoter, the Rous sarcoma virus long terminal repeat, rat insulin promoter and glyceraldehyde-3-phosphate dehydrogenase can be used to obtain high-level expression of the coding sequence of interest. The use of other viral or mammalian cellular or bacterial phage promoters which are well-known in the art to achieve expression of a coding sequence of interest is contemplated as well, provided that the levels of expression are sufficient for a given purpose.

By employing a promoter with well-known properties, the level and pattern of expression of the protein of interest following transfection or transformation can be optimized. Further, selection of a promoter that is regulated in response to specific physiologic signals can permit inducible expression of the gene product. Tables 2 and 3 list several elements/promoters which may be employed, in the context of the present invention, to regulate the expression of the gene of interest. This list is not intended to be exhaustive of all the possible elements involved in the promotion of gene expression but, merely, to be exemplary thereof.

Enhancers are genetic elements that increase transcription from a promoter located at a distant position on the same molecule of DNA. Enhancers are organized much like promoters. That is, they are composed of many individual elements, each of which binds to one or more transcriptional proteins. The basic distinction between enhancers and promoters is operational. An enhancer region as a whole must be able to stimulate transcription at a distance; this need not be true of a promoter region or its component elements. On the other hand, a promoter must have one or more elements that direct initiation of RNA synthesis at a particular site and in a particular orientation, whereas enhancers lack these specificities. Promoters and enhancers are often overlapping and contiguous, often seeming to have a very similar modular organization.

Below is a list of viral promoters, cellular promoters/enhancers and inducible promoters/enhancers that could be used in combination with the nucleic acid encoding a gene of interest in an expression construct (Table 1 and Table 2). Additionally, any promoter/enhancer combination (as per the Eukaryotic Promoter Data Base EPDB) could also be used to drive expression of the gene. Eukaryotic cells can support cytoplasmic transcription from certain bacterial promoters if the appropriate bacterial polymerase is provided, either as part of the delivery complex or as an additional genetic expression construct.

TABLE 1

ENHANCER/PROMOTER

Immunoglobulin Heavy Chain

Immunoglobulin Light Chain

T-Cell Receptor

HLA DQ α and DQ β β-Interferon

Interleukin-2

Interleukin-2 Receptor

MHC Class II 5

MHC Class LI HLA-DRα β-Actin

Muscle Creatine Kinase

Prealbumin (Transthyretin)

Elastase I

Metallothionein

Collagenase

Albumin Gene α-Fetoprotein τ-Globin β-Globin e-fos c-HA-ras

Insulin

Neural Cell Adhesion Molecule (NCAM) αl -Antitrypsin

H2B (TH2B) Histone

Mouse or Type I Collagen

Glucose-Regulated Proteins (GRP94 and GRP78) TABLE 1 (Continued)

Rat Growth Hormone

Human Serum Amyloid A (SAA)

Troponin I (TN I)

Platelet-Derived Growth Factor

Duchenne Muscular Dystrophy

SV40

Polyoma

Retroviruses

Papilloma Virus

Hepatitis B Virus

Human Immunodeficiency Virus

Cytomegalovirus

Gibbon Ape Leukemia Virus

TABLE 2

Where a cDNA insert is employed, one typically will desire to include a polyadenylation signal to effect proper polyadenylation of the gene transcript. The nature of the polyadenylation signal is not believed to be crucial to the successful practice of the invention, and any such sequence may be employed such as human growth hormone and SV40 polyadenylation signals. Also contemplated as an element of the expression cassette is a terminator. These elements can serve to enhance message levels and to minimize read through from the cassette into other sequences.

b. Transgene Constructs Transgene expression will be driven by a selected promoter. The promoter selection will depend on the polypeptide to be expressed, the target tissue and the purpose for expression. For example, if the protein is simply to be produced in vitro and purified, a high level promoter will be utilized. If the protein is toxic to the cells, it may be desirable to regulate the expression of the protein such that cells proliferation is maximized prior to polypeptide expression. If the protein's processing or secretion is dependent upon a particular stage in the host cell's cycle, it may be desirable to employ a promoter that is regulated in an appropriate, cell cycle dependent fashion.

c. Selectable Markers

In certain embodiments of the invention, the cells contain nucleic acid constructs of the present invention, a cell may be identified in vitro or in vivo by including a marker in the expression construct. Such markers would confer an identifiable change to the cell permitting easy identification of cells containing the expression construct. Usually the inclusion of a drug selection marker aids in cloning and in the selection of transformants, for example, genes that confer resistance to neomycin, puromycin, hygromycin, DHFR, GPT, zeocin and histidinol are useful selectable markers. Alternatively, enzymes such as herpes simplex virus thymidine kinase (tk) or chloramphenicol acetyltransferase (CAT) may be employed. Lmmunologic markers also can be employed. The selectable marker employed is not believed to be important, so long as it is capable of being expressed simultaneously with the nucleic acid encoding a gene product. Further examples of selectable markers are well known to one of skill in the art.

d. Multigene Constructs and IRES

In certain embodiments of the invention, the use of internal ribosome binding sites (LRES) elements are used to create multigene, or polycistronic, messages. IRES elements are able to bypass the ribosome scanning model of 5' methylated Cap dependent translation and begin translation at internal sites (Pelletier and Sonenberg, 1988). LRES elements from two members of the picanovirus family (polio and encephalomyocarditis) have been described (Pelletier and Sonenberg, 1988), as well an LRES from a mammalian message (Macejak and Sarnow, 1991). LRES elements can be linked to heterologous open reading frames. Multiple open reading frames can be transcribed together, each separated by an LRES, creating polycistronic messages. By virtue of the LRES element, each open reading frame is accessible to ribosomes for efficient translation. Multiple genes can be efficiently expressed using a single promoter/enhancer to transcribe a single message.

Any heterologous open reading frame can be linked to LRES elements. This includes genes for secreted proteins, multi-subunit proteins, encoded by independent genes, intracellular or membrane-bound proteins and selectable markers. In this way, expression of several proteins can be simultaneously engineered into a cell with a single construct and a single selectable marker.

e. Delivery of Expression Vectors

The present application proposes the use of AAV expression vectors for delivering a gene to a particular host or target cell. However, as noted above, such host cells also require the presence of an FGFR and an HSPG receptor for efficient AAV infection so that the transgene may be efficiently taken up and expressed. Thus, in order to increase the efficiency of AAV-mediated gene delivery, it will be desirable to stimulate, increase or introduce an FGFR and HSPG receptor activity of the host cell. This may be achieved by delivering a gene encoding the receptor to the target cell. This delivery may be achieved using viral or non-viral delivery vectors.

In one embodiment, it may be useful to employ viruses other than AAV to deliver the FGFR and HSPG receptor expression construct. Such viruses may include those that enter cells via receptor-mediated endocytosis, integrate into host cell genome and express viral genes stably and efficiently (Ridgeway, 1988; Nicolas and

Rubenstein, 1988; Baichwal and Sugden, 1986; Temin, 1986). These DNA viruses including the papovaviruses (simian virus 40, bovine papilloma virus, and polyoma) (Ridgeway, 1988; Baichwal and Sugden, 1986), adenoviruses (Ridgeway, 1988; Baichwal and Sugden, 1986) and retroviruses (Coffin, 1990; Mann et al, 1983; Nicolas and Rubenstein, 1988; Temin, 1986; Mann et al, 1983).

In other embodiments, non-viral transfer is contemplated. Several non-viral methods for the transfer of HSPG and/or FGFR receptor expression constructs into cultured mammalian cells are contemplated by the present invention. These include calcium phosphate precipitation (Graham and Van Der Eb, 1973; Chen and Okayama, 1987; Rippe et al, 1990) DEAE-dextran (Gopal, 1985), electroporation (Tur-Kaspa et al, 1986; Potter et al, 1984), direct microinjection (Harland and Weintraub, 1985), DNA-loaded liposomes (Nicolau and Sene, 1982; Fraley et al, 1979) and lipofectamine-DNA complexes, cell sonication (Fechheimer et al, 1987), gene bombardment using high velocity microprojectiles (Yang et al, 1990), and receptor- mediated transfection (Wu and Wu, 1987; Wu and Wu, 1988). Some of these techniques may be successfully adapted for in vivo or ex vivo use.

Once the expression construct has been delivered into the cell, the nucleic acid encoding the gene of interest may be positioned and expressed at different sites. In certain embodiments, the nucleic acid encoding the gene may be stably integrated into the genome of the cell. This integration may be in the cognate location and orientation via homologous recombination (gene replacement) or it may be integrated in a random, non-specific location (gene augmentation). In yet further embodiments, the nucleic acid may be stably maintained in the cell as a separate, episomal segment of DNA. Such nucleic acid segments or "episomes" encode sequences sufficient to permit maintenance and replication independent of or in synchronization with the host cell cycle. How the expression construct is delivered to a cell and where in the cell the nucleic acid remains is dependent on the type of expression construct employed.

In yet another embodiment of the invention, the expression construct containing the receptor gene may simply consist of naked recombinant DNA or plasmids. Transfer of the construct may be performed by any of the methods mentioned above which physically or chemically permeabilize the cell membrane. This is particularly applicable for transfer in vitro but it may be applied to in vivo use as well. Dubensky et al. (1984) successfully injected polyomavirus DNA in the form of calcium phosphate precipitates into liver and spleen of adult and newborn mice demonstrating active viral replication and acute infection. Benvenisty and Neshif (1986) also demonstrated that direct intraperitoneal injection of calcium phosphate- precipitated plasmids results in expression of the transfected genes. It is envisioned that DNA encoding a gene of interest may also be transferred in a similar manner in vivo and express the gene product.

In still another embodiment of the invention for transferring a naked DNA expression construct into cells may involve particle bombardment. This method depends on the ability to accelerate DNA-coated microprojectiles to a high velocity allowing them to pierce cell membranes and enter cells without killing them (Klein et al, 1987). Several devices for accelerating small particles have been developed. One such device relies on a high voltage discharge to generate an electrical current, which in turn provides the motive force (Yang et al, 1990). The microprojectiles used have consisted of biologically inert substances such as tungsten or gold beads.

Selected organs including the liver, skin, and muscle tissue of rats and mice have been bombarded in vivo (Yang et al, 1990; Zelenin et al, 1991). This may require surgical exposure of the tissue or cells, to eliminate any intervening tissue between the gun and the target organ, i.e. ex vivo treatment. Again, DNA encoding a particular gene may be delivered via this method and still be incorporated by the present invention.

In a further embodiment of the invention, the expression construct containing may be entrapped in a liposome. Liposomes are vesicular structures characterized by a phospholipid bilayer membrane and an inner aqueous medium. Multilamellar liposomes have multiple lipid layers separated by aqueous medium. They form spontaneously when phospholipids are suspended in an excess of aqueous solution. The lipid components undergo self-rearrangement before the formation of closed structures and entrap water and dissolved solutes between the lipid bilayers (Ghosh and Bachhawat, 1991). Also contemplated are lipofectamine-DNA complexes.

Liposome-mediated nucleic acid delivery and expression of foreign DNA in vitro has been very successful. Wong et al, (1980) demonstrated the feasibility of liposome-mediated delivery and expression of foreign DNA in cultured chick embryo, HeLa and hepatoma cells. Nicolau et al, (1987) accomplished successful liposome- mediated gene transfer in rats after intravenous injection.

In certain embodiments of the invention, the liposome may be complexed with a hemagglutinating virus (HVJ). This has been shown to facilitate fusion with the cell membrane and promote cell entry of liposome-encapsulated DNA (Kaneda et al, 1989). In other embodiments, the liposome may be complexed or employed in conjunction with nuclear non-histone chromosomal proteins (HMG-1) (Kato et al, 1991). In yet further embodiments, the liposome may be complexed or employed in conjunction with both HVJ and HMG-1. In that such expression constructs have been successfully employed in transfer and expression of nucleic acid in vitro and in vivo, then they are applicable for the present invention. Where a bacterial promoter is employed in the DNA construct, it also will be desirable to include within the liposome an appropriate bacterial polymerase.

Other expression constructs which can be employed to deliver a nucleic acid encoding a particular gene into cells are receptor-mediated delivery vehicles. These take advantage of the selective uptake of macromolecules by receptor-mediated endocytosis in almost all eukaryotic cells. Because of the cell type-specific distribution of various receptors, the delivery can be highly specific (Wu and Wu, 1993).

Receptor-mediated gene targeting vehicles generally consist of two components: a cell receptor-specific ligand and a DNA-binding agent. Several ligands have been used for receptor-mediated gene transfer. The most extensively characterized ligands are asialoorosomucoid (ASOR) (Wu and Wu, 1987) and transferrin (Wagner et al, 1990). Recently, a synthetic neoglycoprotein, which recognizes the same receptor as ASOR, has been used as a gene delivery vehicle (Ferkol et al, 1993; Perales et al, 1994) and epidermal growth factor (EGF) has also been used to deliver genes to squamous carcinoma cells (Myers, EPO 0273085).

In other embodiments, the delivery vehicle may comprise a ligand and a liposome. For example, Nicolau et al, (1987) employed lactosyl-ceramide, a galactose-terminal asialganglioside, incorporated into liposomes and observed an increase in the uptake of the insulin gene by hepatocytes. Thus, it is feasible that a nucleic acid encoding a particular gene also may be specifically delivered into a cell type such as lung, epithelial or tumor cells, by any number of receptor-ligand systems with or without liposomes. For example, epidermal growth factor (EGF) may be used as the receptor for mediated delivery of a nucleic acid encoding a gene in many tumor cells that exhibit upregulation of EGF receptor. Mannose can be used to target the mannose receptor on liver cells. Also, antibodies to CD5 (CLL), CD22 (lymphoma), CD25 (T-cell leukemia) and MAA (melanoma) can similarly be used as targeting moieties.

In certain embodiments, gene transfer may more easily be performed under ex vivo conditions. Ex vivo gene therapy refers to the isolation of cells from an animal, the delivery of a nucleic acid into the cells in vitro, and then the return of the modified cells back into an animal. This may involve the surgical removal of tissue/organs from an animal or the primary culture of cells and tissues.

F. Propagation of AAV Vectors and Transformation of Host Cells

The following is an exemplary description of the propagation of the AAV vectors of the present invention, of course the conditions described are only exemplary and in light of the present disclosure it will be possible for one of ordinary skill in the art to modify these propagation conditions according to particular needs. Transfer of the plasmid may be accomplished any standard gene transfer mechanism: calcium phosphate precipitation, lipofection, electroporation, microprojectile bombardment or other suitable means. Following transfer, host cells may further be infected with a helper virus and the virions are isolated and helper virus is inactivated (e.g., heated at 56°C for one h). The resulting helper free stocks of virions are used to infect appropriate target cells. Mature virions may further be isolated by standard methods, e.g., cesium chloride centrifugation, and to inactivate any contaminating adenovirus.

Function of the vectors of the present invention, i.e. the ability to mediate transfer and expression of the heterologous gene in hematopoietic stem or progenitor cells, can be evaluated by monitoring the expression of the heterologous gene in transduced cells. Obviously, the assay for expression depends upon the nature of the heterologous gene. Expression can be monitored by a variety of methods including immunological, histochemical or activity assays. For example, Northern analysis can be used to assess transcription using appropriate DNA or RNA probes. If antibodies to the polypeptide encoded by the heterologous gene are available, Western blot analysis, immunohistochemistry or other immunological techniques can be used to assess the production of the polypeptide. Appropriate biochemical assays also can be used if the heterologous gene is an enzyme. For example, if the heterologous gene encodes antibiotic resistance, a determination of the resistance of infected cells to the antibiotic can be used to evaluate expression of the antibiotic resistance gene.

Site-specific integration can be assessed, for example, by Southern blot analysis. DNA is isolated from cells transduced by the vectors of the present invention, digested with a variety of restriction enzymes, and analyzed on Southern blots with an AAV-specific probe. A single band of hybridization evidences site- specific integration. Other methods known to the skilled artisan, such as polymerase chain reaction (PCR) analysis of chromosomal DNA can be used to assess stable integration.

G. Cell Culture and Selection In one embodiment, the present invention contemplates the use of AAV vectors to transform cells for the production of mammalian cell cultures for use in the various therapeutic aspects of the present invention. In order for the cells to be kept viable while in vitro and in contact with the expression construct, it is necessary to ensure that the cells are maintained with the correct ratio of oxygen and carbon dioxide and nutrients, but are protected from microbial contamination. Cell culture techniques are well documented and are disclosed herein by reference (Freshner, 1992).

The construct encoding the protein of interest may be transferred by the viral vector, as described above, into appropriate host cells followed by culture of cells under the appropriate conditions. The gene for virtually any polypeptide may be employed in this manner. Examples of useful mammalian cell lines are those that express the appropriate receptor for B 19 virus. These include cells derived from bone marrow cells, peripheral blood cells and fetal liver cells.

Bone marrow cells are isolated and enriched for hematopoietic stem cells (HSC), e.g., by fluorescence activated cell sorting as described in Srivastava et al. (1988). HSC are capable of self-renewal as well as initiating long-term hematopoiesis and differentiation into multiple hematopoietic lineages in vitro. HSC are transfected with the vector of the present invention or infected with varying concentrations of virions containing a subject hybrid vector and then assessed for the expression of the heterologous gene. The assay for expression depends upon the nature of the heterologous gene. Expression can be monitored by a variety of methods including immunological, histochemical or activity assays. For example, Northern analysis can be used to assess transcription using appropriate DNA or RNA probes. If antibodies to the polypeptide encoded by the heterologous gene are available, Western blot analysis, immunohistochemistry or other immunological techniques can be used to assess the production of the polypeptide. Appropriate biochemical assays also can be used if the heterologous gene is an enzyme. For example, if the heterologous gene encodes antibiotic resistance, a determination of the resistance of infected cells to the antibiotic can be used to evaluate expression of the antibiotic resistance gene.

An important consideration is the appropriate modification needed for a particular polypeptide. Such modifications (e.g., glycosylation) and processing (e.g., cleavage) of protein products may be important for the function of the protein. Different host cells have characteristic and specific mechanisms for the post- translational processing and modification of proteins. Appropriate cell lines or host systems can be chosen to insure the correct modification and processing of the protein expressed.

Examples of useful mammalian host cell lines are Vero and HeLa cells and cell lines of Chinese hamster ovary, W138, BHK, COS-7, 293, HepG2, NLH3T3, RLN and MDCK cells. In addition, a host cell strain may be chosen that modulates the expression of the inserted sequences, or modifies and process the gene product in the manner desired. Such modifications (e.g., glycosylation) and processing (e.g., cleavage) of protein products may be important for the function of the protein. Different host cells have characteristic and specific mechanisms for the post- translational processing and modification of proteins. Appropriate cell lines or host systems can be chosen to insure the correct modification and processing of the foreign protein expressed.

A number of selection systems may be used including, but not limited to, HSV thymidine kinase, hypoxanthine-guanine phosphoribosyltransferase and adenine phosphoribosyltransferase genes, in tk-, hgprt- or aprt- cells, respectively. Also, anti- metabolite resistance can be used as the basis of selection for dhfr, that confers resistance to; gpt, that confers resistance to mycophenolic acid; neo, that confers resistance to the aminoglycoside G418; and hygro, that confers resistance to hygromycin.

Animal cells can be propagated in vitro in two modes: as non-anchorage dependent cells growing in suspension throughout the bulk of the culture or as anchorage-dependent cells requiring attachment to a solid substrate for their propagation (i.e. a monolayer type of cell growth).

Non-anchorage dependent or suspension cultures from continuous established cell lines are the most widely used means of large scale production of cells and cell products. However, suspension cultured cells have limitations, such as tumorigenic potential and lower protein production than adherent T-cells.

Large scale suspension culture of mammalian cells in stirred tanks is a common method for production of recombinant proteins. Two suspension culture reactor designs are in wide use - the stirred reactor and the airlift reactor. The stirred design has successfully been used on an 8000 liter capacity for the production of interferon. Cells are grown in a stainless steel tank with a height-to-diameter ratio of 1: 1 to 3: 1. The culture is usually mixed with one or more agitators, based on bladed disks or marine propeller patterns. Agitator systems offering less shear forces than blades have been described. Agitation may be driven either directly or indirectly by magnetically coupled drives. Indirect drives reduce the risk of microbial contamination through seals on stirrer shafts.

The airlift reactor, also initially described for microbial fermentation and later adapted for mammalian culture, relies on a gas stream to both mix and oxygenate the culture. The gas stream enters a riser section of the reactor and drives circulation. Gas disengages at the culture surface, causing denser liquid free of gas bubbles to travel downward in the downcomer section of the reactor. The main advantage of this design is the simplicity and lack of need for mechanical mixing. Typically, the height-to-diameter ratio is 10:1. The airlift reactor scales up relatively easily, has good mass transfer of gases and generates relatively low shear forces.

The antibodies of the present invention are particularly useful for the isolation of antigens by immunoprecipitation. Immunoprecipitation involves the separation of the target antigen component from a complex mixture, and is used to discriminate or isolate minute amounts of protein. For the isolation of membrane proteins cells must be solubilized into detergent micelles. Nonionic salts are preferred, since other agents such as bile salts, precipitate at acid pH or in the presence of bivalent cations. Antibodies are and their uses are discussed further, below. H. Transgenes

For gene therapy with an AAV vector, virtually any transgene may be utilized in the vectors described herein. In a preferred embodiment, the heterologous gene encodes a biologically functional protein, i.e. a polypeptide or protein which affects the cellular mechanism of a cell in which the biologically functional protein is expressed. For example, the biologically functional protein can be a protein which is essential for normal growth of the cell or for maintaining the health of a mammal. The biologically functional protein also can be a protein which improves the health of a mammal by either supplying a missing protein, by providing increased quantities of a protein which is underproduced in the mammal or by providing a protein which inhibits or counteracts an undesired molecule which may be present in the mammal. The biologically functional protein also can be a protein which is a useful protein for investigative studies for developing new gene therapies or for studying cellular mechanisms.

Expression of several proteins that are normally secreted can be engineered into cells. The cDNA's encoding a number of useful human proteins are available. Examples would include soluble CD-4, Factor VLΪ, Factor DC, von Willebrand Factor, TPA, urokinase, hirudin, interferons, TNF, interleukins, hematopoietic growth factors, antibodies, albumin, leptin, transferin and nerve growth factors.

Expression of non-secreted proteins can be engineered into cells. Two general classes of such proteins can be defined. The first are proteins that, once expressed in cells, stay associated with the cells in a variety of destinations. These destinations include the cytoplasm, nucleus, mitochondria, endoplasmic reticulum, Golgi, membrane of secretory granules and plasma membrane. Non-secreted proteins are both soluble and membrane associated. The second class of proteins are ones that are normally associated with the cell, but have been modified such that they are now secreted by the cell. Modifications would include site-directed mutagenesis or expression of truncations of engineered proteins resulting in their secretion as well as creating novel fusion proteins that result in secretion of a normally non-secreted protein. p53 currently is recognized as a tumor suppressor gene (Montenarh, 1992). High levels of mutant p53 have been found in many cells transformed by chemical carcinogenesis, ultraviolet radiation, and several viruses, including SV40. The p53 gene is a frequent target of mutational inactivation in a wide variety of human tumors and is already documented to be the most frequently-mutated gene in common human cancers (Mercer, 1992). It is mutated in over 50% of human NSCLC (Hollestein et al, 1991) and in a wide spectrum of other tumors.

The p53 gene encodes a 393-amino-acid phosphoprotein that can form complexes with host proteins such as large-T antigen and E1B. The protein is found in normal tissues and cells, but at concentrations which are generally minute by comparison with transformed cells or tumor tissue. Interestingly, wild-type p53 appears to be important in regulating cell growth and division. Overexpression of wild-type p53 has been shown in some cases to be anti-proliferative in human tumor cell lines. Thus, p53 can act as a negative regulator of cell growth (Weinberg, 1991) and may directly suppress uncontrolled cell growth or directly or indirectly activate genes that suppress this growth. Thus, absence or inactivation of wild-type p53 may contribute to transformation. However, some studies indicate that the presence of mutant p53 may be necessary for full expression of the transforming potential of the gene.

Wild-type p53 is recognized as an important growth regulator in many cell types. Missense mutations are common for the p53 gene and are known to occur in at least 30 distinct codons, often creating dominant alleles that produce shifts in cell phenotype without a reduction to homozygosity. Additionally, many of these dominant negative alleles appear to be tolerated in the organism and passed on in the germ line. Various mutant alleles appear to range from minimally dysfunctional to strongly penetrant, dominant negative alleles (Weinberg, 1991).

Casey and colleagues have reported that transfection of DNA encoding wild- type p53 into two human breast cancer cell lines restores growth suppression control in such cells (Casey et al, 1991). A similar effect has also been demonstrated on transfection of wild-type, but not mutant, p53 into human lung cancer cell lines (Takahasi et al, 1992). p53 appears dominant over the mutant gene and will select against proliferation when transfected into cells with the mutant gene. Normal expression of the transfected p53 is not detrimental to normal cells with endogenous wild-type p53. Thus, such constructs might be taken up by normal cells without adverse effects. It is thus proposed that the treatment of p53-associated cancers with wild-type p53 expression constructs will reduce the number of malignant cells or their growth rate. Furthermore, recent studies suggest that some p53 wild-type tumors are also sensitive to the effects of exogenous p53 expression.

The major transitions of the eukaryotic cell cycle are triggered by cyclin- dependent kinases, or CDK's. One CDK, cyclin-dependent kinase 4 (CDK4), regulates progression through the Gi phase. The activity of this enzyme may be to phosphorylate Rb at late Gj. The activity of CDK4 is controlled by an activating subunit, D-type cyclin, and by an inhibitory subunit, e.g., γ\ ^m ,which has been biochemically characterized as a protein that specifically binds to and inhibits CDK4, and thus may regulate Rb phosphorylation (Serrano et al, 1993; Serrano et al, 1995). Since the \6^mκ protein is a CDK4 inhibitor (Serrano, 1993), deletion of this gene may increase the activity of CDK4, resulting in hyperphosphorylation of the Rb protein. pl6 also is known to regulate the function of CDK6.

pι( ^iNK4 belongs to a newly described class of CDK-inhibitory proteins that also includes pl6^B, p21^WAF1' ^cm' ^SDπ, and p27^KIPI. The plό^⁴ gene maps to 9p21, a chromosome region frequently deleted in many tumor types. Homozygous deletions and mutations of the plό¹¹^⁴ gene are frequent in human tumor cell lines. This evidence suggests that the plό¹¹^⁴ gene is a tumor suppressor gene. This interpretation has been challenged, however, by the observation that the frequency of the pi 6 ^K4 gene alterations is much lower in primary uncultured tumors than in cultured cell lines (Caldas et al, 1994; Cheng et al, 1994; Hussussian et al, 1994; Kamb et al, 1994a; Kamb et al, 1994b; Mori et al, 1994; Okamoto et al, 1994; Nobori et al, 1995; Orlow et al, 1994; Arap et al, 1995). Restoration of wild-type pjg^iNK4 f_unctj_on by transfection with a plasmid expression vector reduced colony formation by some human cancer cell lines (Okamoto, 1994; Arap, 1995).

C-CAM is expressed in virtually all epithelial cells (Odin and Obrink, 1987). C-CAM, with an apparent molecular weight of 105 kD, was originally isolated from the plasma membrane of the rat hepatocyte by its reaction with specific antibodies that neutralize cell aggregation (Obrink, 1991). Recent studies indicate that, structurally, C-CAM belongs to the immunoglobulin (lg) superfamily and its sequence is highly homologous to carcinoembryonic antigen (CEA) (Lin and Guidotti, 1989). Using a baculovirus expression system, Cheung et al. (1993a; 1993b and 1993c) demonstrated that the first lg domain of C-CAM is critical for cell adhesion activity.

Cell adhesion molecules, or CAMs are known to be involved in a complex network of molecular interactions that regulate organ development and cell differentiation (Edelman, 1985). Recent data indicate that aberrant expression of CAMs may be involved in the tumorigenesis of several neoplasms; for example, decreased expression of E-cadherin, which is predominantly expressed in epithelial cells, is associated with the progression of several kinds of neoplasms (Edelman and Crossin, 1991; Frixen et al, 1991; Bussemakers et al, 1992; Matsura et al, 1992; Umbas et al, 1992). Also, Giancotti and Ruoslahti (1990) demonstrated that increasing expression of α₅βι integrin by gene transfer can reduce tumorigenicity of Chinese hamster ovary cells in vivo. C-CAM now has been shown to suppress tumor growth in vitro and in vivo.

Other tumor suppressors that may be employed according to the present invention include RB, APC, DCC, NF-1, NF-2, WT-1, MEN-I, MEN-LI, zacl, p73, BRCA1, VHL, FCC, MMAC1, MCC, pl6, p21, p57, C-CAM, p27 and BRCA2. Inducers of apoptosis, such as Bax, Bak, Bcl-X_s, Bik, Bid, Harakiri, Ad E1B, Bad and ICE-CED3 proteases, similarly could find use according to the present invention.

Various enzyme genes are of interest according to the present invention. Such enzymes include cytosine deaminase, hypoxanthine-guanine phosphoribosyltransferase, galactose-1 -phosphate uridyltransferase, phenylalanine hydroxylase, glucocerbrosidase, sphingomyelinase, α-L-iduronidase, glucose-6- phosphate dehydrogenase, HSV thymidine kinase and human thymidine kinase.

Hormones are another group of gene that may be used in the vectors described herein. Included are growth hormone, prolactin, placental lactogen, luteinizing hormone, follicle-stimulating hormone, chorionic gonadotropin, thyroid-stimulating hormone, leptin, adrenocorticotropin (ACTH), angiotensin I and LI, β-endorphin, β- melanocyte stimulating hormone (β-MSH), cholecystokinin, endothelin I, galanin, gastric inhibitory peptide (GLP), glucagon, insulin, lipotropins, neurophysins, somatostatin, calcitonin, calcitonin gene related peptide (CGRP), β-calcitonin gene related peptide, hypercalcemia of malignancy factor (1-40), parathyroid hormone- related protein (107-139) (PTH-rP), parathyroid hormone-related protein (107-111) (PTH-rP), glucagon-like peptide (GLP-1), pancreastatin, pancreatic peptide, peptide YY, PHM, secretin, vasoactive intestinal peptide (VIP), oxytocin, vasopressin (AVP), vasotocin, enkephalinamide, metorphinamide, alpha melanocyte stimulating hormone (alpha-MSH), atrial natriuretic factor (5-28) (ANF), amylin, amyloid P component (SAP-1), corticotropin releasing hormone (CRH), growth hormone releasing factor (GHRH), luteinizing hormone-releasing hormone (LHRH), neuropeptide Y, substance K (neurokinin A ), substance P and thyrotropin releasing hormone (TRH). The cDNA's encoding a number of therapeutically useful human proteins are available. Other proteins include protein processing enzymes such as PC2 and PC3, and PAM, transcription factors such as LPF1, and metabolic enzymes such as adenosine deaminase, phenylalanine hydroxylase, glucocerebrosidase.

Other classes of genes that are contemplated to be inserted into the vectors of the present invention include interleukins and cytokines. Interleukin 1 (LL-1), LL-2, LL-3, LL-4, LL-5, LL-6, LL-7, LL-8, LL-9, LL-10, LL-11 LL-12, GM-CSF and G-CSF.

Examples of diseases for which the present viral vector would be useful include, but are not limited to, adenosine deaminase deficiency, human blood clotting factor LX deficiency in hemophilia B, and cystic fibrosis, which would involve the replacement of the cystic fibrosis transmembrane receptor gene. The vectors embodied in the present invention could also be used for treatment of hyperproliferative disorders such as rheumatoid arthritis or restenosis by transfer of genes encoding angiogenesis inhibitors or cell cycle inhibitors. Transfer of prodrug activators such as the HSV-TK gene can be also be used in the treatment of hyperproliferative disorders, including cancer.

Other therapeutics genes might include genes encoding antigens such as viral antigens, bacterial antigens, fungal antigens or parasitic antigens. Viruses include picomavirus, coronavirus, togavirus, flavirviru, rhabdovirus, paramyxovirus, orthomyxovirus, bunyavirus, arenvirus, reovirus, retrovirus, papovavirus, parvovirus, herpesvirus, poxvirus, hepadnavirus, and spongiform virus. Preferred viral targets include influenza, herpes simplex virus 1 and 2, measles, small pox, polio or HIV. Pathogens include trypanosomes, tapeworms, roundworms, helminths, . Also, tumor markers, such as fetal antigen or prostate specific antigen, may be targeted in this manner. Preferred examples include HIV env proteins and hepatitis B surface antigen. Administration of a vector according to the present invention for vaccination purposes would require that the vector-associated antigens be sufficiently non-immunogenic to enable long term expression of the transgene, for which a strong immune response would be desired. Preferably, vaccination of an individual would only be required infrequently, such as yearly or biennially, and provide long term immunologic protection against the infectious agent.

Cells engineered to produce such proteins could be used for either in vitro production of the protein or for in vivo, cell-based therapies. In vitro production would entail purification of the expressed protein from either the cell pellet for proteins remaining associated with the cell or from the conditioned media from cells secreting the engineered protein. In vivo, cell-based therapies would either be based on secretion of the engineered protein or beneficial effects of the cells expressing a non-secreted protein. Engineering mutated, truncated or fusion proteins into cells also is contemplated. Examples of each type of engineering resulting in secretion of a protein are given (Ferber et al, 1991; Mains et al, 1995). Reviews on the use of such proteins for studying the regulated secretion pathway also are cited (Burgess and Kelly, 1987; Chavez et al. , 1994) .

I. Methods of Altering Receptor Activity

As stated above, the present invention provides methods for increasing the transduction efficiency of AAV infection in, for example, gene therapy. These methods exploit the inventors' observation, described in detail herein, that expression of the FGFR receptor is required, in addition to cell surface expression of HSPG, for efficient AAV infection. It is, therefore, a goal of the present invention to exploit this observation. This exploitation takes, basically, two forms. First, by observing the FGFR receptor expression of a cell, alone or in conjunction with the observation of HSPG expression, one can determine the susceptibility of that cell to infection by AAV (see U.S. Patents 5,229,501 and 5,707,632). Second, upon a determination that one or both of these receptors are missing from a target cell, it is possible to render that target cell susceptible by increasing the presence of one or both of these receptors on the cell surface.

There are at least three different methods through which FGFR receptor expression on the cell surface may be increased. First, one may simply increase the amount of mature endogenous FGFR receptor that is contained in the cell, with the expected result of increased cell surface expression. This may involve increasing transcription, translation, or post-translational processing. It also may involve increasing the stability of FGFR, for example, by reducing turnover or receptor cycling. While the regulation of FGFR is not completely elucidated, many cell surface receptor molecules exhibit a complex, autoregulatory mechanism, whereby binding and internalization of the receptor-ligand complex stimulates increased transcription and translation of the receptor. Therefore, a fruitful approach may involve the use of FGFR peptides or analogs that, following internalization, cause increased expression of the receptor. Classic pharmaceuticals also may be utilized which affect FGFR levels.

Second, one may provide a cell with an FGFR gene, in an expression construct, that will facilitate expression of the receptor in increased quantities. The various aspects of this embodiment are described in detail throughout the relevant portions of this document. Briefly, one would provide a target cells with an appropriate vector encoding the FGFR gene of choice, under the control of a promoter active in that target cell. The promoter, either constitutively or under some form of induction, would stimulate transcription of the FGFR gene, resulting in expression of the receptor. Subsequent infection of the cell with an AAV particle should be enhanced by the increased cell surface FGFR.

Third, one may directly increase the ability of existing FGFR receptor to bind AAV by treating the cell with an agent, presumably one that binds to the FGFR protein or a closely related molecules. Many receptors exhibit so-called "allosteric" effects, where binding of a ligand to one part of the molecule will affect the structure, and possibly function, of another part. In this embodiment, FGF peptides may serve themselves, or as useful models for other molecules, which bind FGFR and improve the receptor' s ability to bind AAV.

J. Methods of Therapy

The vectors of the present invention are useful for gene therapy, the therapy consists of administering vector and increasing, stimulating or otherwise providing a function FGFR or HSPG receptor activity/function to the host cell. In particular embodiments, the vectors of the present invention can direct cell-specific expression of a desired gene, and thus are useful in the treatment of hemoglobinopathies. Such maladies include thalassemia, sickle-cell anemia, diabetes, and cancer. The heterologous gene, in this context, can be the normal counterpart of one that is abnormally produced or underproduced in the disease state, for example β-globin for the treatment of sickle-cell anemia, and α-globin, β-globin or γ-globin in the treatment of thalassemia. The heterologous gene can encode antisense RNA as described hereinabove. For example, α-globin is produced in excess over β-globin in β- thalassemia. Accordingly, β-thalassemia can be treated in accordance with the present invention by gene therapy with a vector in which the heterologous gene encodes an antisense RNA. The antisense RNA is selected such that it binds to a target sequence of the α-globin mRNA to prevent translation of α-globin, or to a target sequence of the α-globin DNA such that binding prevents transcription of α-globin DNA. In the treatment of cancer the heterologous gene can be a gene associated with tumor suppression, such as retinoblastoma gene, p53, pl6, p21 or the gene encoding tumor necrosis factor.

The use of the vectors of the present invention for the treatment of disease involves, in one embodiment, the transduction of hematopoeitic stems cells or progenitor cells with the claimed vectors in combination with the provision of an active receptor that will mediate the efficient infection of the host cell by the AAV vector. Transduction is accomplished, following preparation of mature virions containing the AAV vectors, by infection of HSC or progenitor cells therewith. Transduced cells may be located in patients or transduced ex vivo and introduced or reintroduced into patients, e.g., by intravenous transfusion (Rosenberg, 1990).

In ex vivo embodiments, HSC or progenitor cells are provided by obtaining bone marrow cells from patients and optionally enriching the bone marrow cell population for HSC. HSC can be transduced by standard methods of transfection or infected with mature virions for about 1 to 2 hours at about 37°C. Stable integration of the viral genome is accomplished by incubation of HSC at about 37°C for about one week to about one month. The stable, site-specific integration and erythroid cell- specific expression is assessed as described above. After the transduced cells have been introduced into a patient, the presence of the heterologous gene product can be monitored or assessed by an appropriate assay for the gene product in the patient, for example in peripheral red blood cells or bone marrow of the patient when expression is erythroid cell-specific. As described above, the specific assay is dependent upon the nature of the heterologous gene product and can readily be determined by one skilled in the art.

a. Combined Therapy The present invention has described methods of increasing the efficiency of

AAV-mediated gene transcription by providing expression constructs encoding the therapeutic gene of interest in combination with an FGFR and or cell surface HSPG. Efficient gene transfer by AAV has been attributed the presence of an FGFR co- receptor to mediate the uptake of the AAV once it has bound to the HSPG. Thus, efficient transcription may be achieved by providing the expression construct containing the therapeutic transgene in combination with an expression construct containing an FGFR receptor or an HSPG receptor or both. Alternatively, the host receptor(s) may be stimulated, upregulated or otherwise encouraged to take-up AAV by provision of a stimulator of these receptors in combination with the transgene expression construct.

To stimulate the endogenous receptors or provide for the expression of such receptors in the target cells, using the methods and compositions of the present invention, one would generally contact a "target" cell with the stimulator or expression construct and contact the cell with the therapeutic transgenic construct (gene therapy). These compositions would be provided in a combined amount effective to increase the AAV infection efficiency. This process may involve contacting the cells with the gene therapy and the receptor encoding constructs at the same time. This may be achieved by contacting the cell with a single composition that includes both the therapeutic gene and the receptor gene(s), or by contacting the cell with two distinct compositions at the same time, wherein one composition includes the therapeutic expression construct and the other includes the receptor expression construct.

In addition to ensuring an efficient uptake of the AAV, it may be beneficial to provide agents or factors suitable for use in a combined therapy with the therapeutic expression construct. The inventors propose that the local or regional delivery of vector constructs to patients in need of gene therapy in combination with the receptor expression will be a very efficient method for delivering a therapeutically effective gene to counteract the clinical disease. Alternatively, systemic delivery of therapeutic expression construct may be appropriate in certain circumstances, for example, where extensive metastasis has occurred.

K. Formulations and Routes for Administration to Patients Where clinical applications are contemplated, it will be necessary to prepare pharmaceutical compositions - expression vectors, virus stocks, proteins, antibodies and drugs - in a form appropriate for the intended application. Generally, this will entail preparing compositions that are essentially free of pyrogens, as well as other impurities that could be harmful to humans or animals.

One will generally desire to employ appropriate salts and buffers to render delivery vectors stable and allow for uptake by target cells. Buffers also will be employed when recombinant cells are introduced into a patient. Aqueous compositions of the present invention comprise an effective amount of the vector to cells, dissolved or dispersed in a pharmaceutically acceptable carrier or aqueous medium. Such compositions also are referred to as inocula. The phrase "pharmaceutically or pharmacologically acceptable" refer to molecular entities and compositions that do not produce adverse, allergic, or other untoward reactions when administered to an animal or a human. As used herein, "pharmaceutically acceptable carrier" includes any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents and the like. The use of such media and agents for pharmaceutically active substances is well know in the art. Except insofar as any conventional media or agent is incompatible with the vectors or cells of the present invention, its use in therapeutic compositions is contemplated. Supplementary active ingredients also can be incorporated into the compositions. The active compositions of the present invention may include classic pharmaceutical preparations. Administration of these compositions according to the present invention will be via any common route so long as the target tissue is available via that route. This includes oral, nasal, buccal, rectal, vaginal or topical. Alternatively, administration may be by orthotopic, intradermal, subcutaneous, intramuscular, intraperitoneal or intravenous injection. Such compositions would normally be administered as pharmaceutically acceptable compositions, described supra.

The active compounds also may be administered parenterally or intraperitoneally. Solutions of the active compounds as free base or pharmacologically acceptable salts can be prepared in water suitably mixed with a surfactant, such as hydroxypropylcellulose. Dispersions also can be prepared in glycerol, liquid polyethylene glycols, and mixtures thereof and in oils. Under ordinary conditions of storage and use, these preparations contain a preservative to prevent the growth of microorganisms.

The pharmaceutical forms suitable for injectable use include sterile aqueous solutions or dispersions and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersions. In all cases the form must be sterile and must be fluid to the extent that easy syringability exists. It must be stable under the conditions of manufacture and storage and must be preserved against the contaminating action of microorganisms, such as bacteria and fungi. The carrier can be a solvent or dispersion medium containing, for example, water, ethanol, polyol (for example, glycerol, propylene glycol, and liquid polyethylene glycol, and the like), suitable mixtures thereof, and vegetable oils. The proper fluidity can be maintained, for example, by the use of a coating, such as lecithin, by the maintenance of the required particle size in the case of dispersion and by the use of surfactants. The prevention of the action of microorganisms can be brought about by various antibacterial an antifungal agents, for example, parabens, chlorobutanol, phenol, sorbic acid, thimerosal, and the like. In many cases, it will be preferable to include isotonic agents, for example, sugars or sodium chloride. Prolonged absorption of the injectable compositions can be brought about by the use in the compositions of agents delaying absorption, for example, aluminum monostearate and gelatin.

Sterile injectable solutions are prepared by incorporating the active compounds in the required amount in the appropriate solvent with various of the other ingredients enumerated above, as required, followed by filtered sterilization. Generally, dispersions are prepared by incorporating the various sterilized active ingredients into a sterile vehicle which contains the basic dispersion medium and the required other ingredients from those enumerated above. In the case of sterile powders for the preparation of sterile injectable solutions, the preferred methods of preparation are vacuum-drying and freeze-drying techniques which yield a powder of the active ingredient plus any additional desired ingredient from a previously sterile-filtered solution thereof.

As used herein, "pharmaceutically acceptable carrier" includes any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents and the like. The use of such media and agents for pharmaceutical active substances is well known in the art. Except insofar as any conventional media or agent is incompatible with the active ingredient, its use in the therapeutic compositions is contemplated. Supplementary active ingredients also can be incorporated into the compositions.

For oral administration the polypeptides of the present invention may be incorporated with excipients and used in the form of non-ingestible mouthwashes and dentifrices. A mouthwash may be prepared incorporating the active ingredient in the required amount in an appropriate solvent, such as a sodium borate solution (Dobell's Solution). Alternatively, the active ingredient may be incorporated into an antiseptic wash containing sodium borate, glycerin and potassium bicarbonate. The active ingredient may also be dispersed in dentifrices, including: gels, pastes, powders and slurries. The active ingredient may be added in a therapeutically effective amount to a paste dentifrice that may include water, binders, abrasives, flavoring agents, foaming agents, and humectants. The compositions of the present invention may be formulated in a neutral or salt form. Pharmaceutically-acceptable salts include the acid addition salts (formed with the free amino groups of the protein) and which are formed with inorganic acids such as, for example, hydrochloric or phosphoric acids, or such organic acids as acetic, oxalic, tartaric, mandelic, and the like. Salts formed with the free carboxyl groups also can be derived from inorganic bases such as, for example, sodium, potassium, ammonium, calcium, or ferric hydroxides, and such organic bases as isopropylamine, trimethylamine, histidine, procaine and the like.

Upon formulation, solutions will be administered in a manner compatible with the dosage formulation and in such amount as is therapeutically effective. The formulations are easily administered in a variety of dosage forms such as injectable solutions, drug release capsules and the like. For parenteral administration in an aqueous solution, for example, the solution should be suitably buffered if necessary and the liquid diluent first rendered isotonic with sufficient saline or glucose. These particular aqueous solutions are especially suitable for intravenous, intramuscular, subcutaneous and intraperitoneal administration. In this connection, sterile aqueous media which can be employed will be known to those of skill in the art in light of the present disclosure. For example, one dosage could be dissolved in 1 ml of isotonic NaCI solution and either added to 1000 ml of hypodermoclysis fluid or injected at the proposed site of infusion, (see for example, "Remington's Pharmaceutical Sciences" 15th Edition, pages 1035-1038 and 1570-1580). Some variation in dosage will necessarily occur depending on the condition of the subject being treated. The person responsible for administration will, in any event, determine the appropriate dose for the individual subject. Moreover, for human administration, preparations should meet sterility, pyrogenicity, general safety and purity standards as required by FDA Office of Biologies standards.

L. Examples

The following examples are included to demonstrate preferred embodiments of the invention. It should be appreciated by those of skill in the art that the techniques disclosed in the examples which follow represent techniques discovered by the inventor to function well in the practice of the invention, and thus can be considered to constitute preferred modes for its practice. However, those of skill in the art should , in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the concept, spirit and scope of the invention. More specifically, it will be apparent that certain agents which are both chemically and physiologically related may be substituted for the agents described herein while the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.

EXAMPLE 1 Materials and Methods Cells, plasmids, and viruses. The human cervical carcinoma cell line HeLa, the human adenovirus- transformed human embryonic kidney cell line 293, and murine fibroblast NLH3T3 cells were obtained from the American Type Culture Collection (Rockville, MD). The human naso-pharyngeal carcinoma cell line KB, the human lymphoblastoid cell line Raji, and the human megakaryocytic leukemia cell line M07e, were obtained respectively from Drs. Asok C. Antony, Zacharie A. Brahmi, and Hal E. Broxmeyer (Indiana University School of Medicine, Indianapolis, LN). Monolayer cultures of HeLa, KB, 293, and NLH3T3, and suspension cultures of M07e and Raji were maintained in Iscove's-modified Dulbecco's medium (LMDM) supplemented with 10% fetal bovine serum (FBS) and 1% antibiotics. The recombinant murine HSPG (Syndecan-1) (Saunders et al, 1989) was obtained from Dr. Bradley B. Olwin, University of Colorado, Boulder, CO. The recombinant plasmid pSV7d hFGFRl containing the SV40 promoter-driven cDNA for human fibroblast growth factor receptor 1 (FGFRl) has been described previously (Johnson et al, 1990), and was obtained from Dr. Lewis T. Williams (University of California, San Francisco, CA). Recombinant AAV plasmid pCMVp-/αcZ containing the CMVp-driven b- galactosidase (lacZ) gene has been described elsewhere (Ponnazhagan et al, 1997, Ponnazhagan et al, 1997). Wild-type (wt) and recombinant AAV vector (vCMVp- lacZ) stocks were generated and purified by CsCl equilibrium density gradient centrifugation as previously described (Ponnazhagan et al, 1997 ', Qing et al, 1997, Qing et al, 1998, Ponnazhagan et al, 1997, Ponnazhagan et al, 1997). Physical particle titers of wt and recombinant vector stocks were determined by quantitative DNA slot blot analysis (Kube and Srivastava, 1997). Physical particle infectious particle ratio (approximately 1000:1), and the contaminating wild-type AAV-like particle titer (approximately 0.01%) in the recombinant vector stocks were determined as previously described (Wang et al, 1998). AAV-binding assay.

AAV-binding studies were carried out as previously described (Qing et al, 1998, Ponnazhagan et al, 1997). Briefly, 5 x 10⁴ cells were washed twice with LMDM containing 1% BSA. One ml of LMDM containing 1% BSA was added to the

8 35 cells with either 1.5 xlO particles of [ S] methionine-labeled wt AAV alone or with 100-fold excess of unlabeled wt AAV particles for 90 min. at 4°C. Following incubation, cells were washed four times with LMDM containing 1% BSA and solubilized with 1 ml 0.5 N NaOH for 30 min at room temperature. Radioactivity of lysates was determined and specific binding was calculated as the total radioactivity minus the non-specific radioactivity as previously described (Qing et al, 1998).

FGF-binding assay.

FGF-binding experiments were carried out as previously described by Kan et al. (1993) with the following modifications. Briefly, 5 x 10⁴ cells were washed twice with LMDM containing 0.1% BSA. One ml of LMDM containing 0.1% BSA was added to all cells either with 0.5 ng/ml ¹²⁵I-bFGF obtained from Amersham (Arlington Heights, LL) alone or with large excess unlabeled bFGF (Sigma Chemical Co., St. Louis, MO). Cells were incubated for 90 min. at room temp. Following incubation, cells were loaded on Whatman GF/C glass fiber filters and washed four times with LMDM containing 0.1% BSA to remove free ¹²⁵I-bFGF from cell- associated bFGF. Radioactivity of lysates was determined in a Beckman Gamma counter. Specific binding was calculated as the total radioactivity minus the nonspecific radioactivity.

Stable transfection with HSPG and/or FGFRl expression plasmids.

Transfection of M07e and Raji cells with different expression plasmid DNAs was carried out using the DMRLE-C reagent according to the protocol provided by the vendor (Gibco-BRL, Grand Island, NY). Selectable marker genes (Hyg^R and Neo^R) were inserted into HSPG and FGFRl cDNA expression plasmids, respectively, by standard cloning methods. Either G418, hygromycin, or both, were added at a final cone, of 400 mg/ml and 300 mg/ml, respectively, 48 hrs post-transfection, and individual drug-resistant cell clones were isolated after 28 days of selection.

Recombinant AAV transduction assays. Approximately equivalent numbers of cells were washed once with LMDM and then infected with the recombinant vCMVp-ZαcZ vector at various indicated particles/cell. Forty-eight h post-infection (p.i.), cells were either fixed and stained with X-gal (5-bromo-4-chloro-3-indolyl b-D-galactopyranoside) and the numbers of blue cells were enumerated, or analyzed by FACS as previously described (Ponnazhagan et al, 1997, Qing et al, 1997, Qing et al, 1998, Ponnazhagan et al, 1997, Ponnazhagan et al, 1997). In some studies, following infection with the recombinant vCMVp-ZαcZ vector, cells were washed extensively with PBS, and low M_r DNA samples isolated from equivalent numbers of cells were analyzed on Southern blots using the lacZ DNA probe as described previously (Ponnazhagan et al, 1997).

Cellular tyrosine kinase inhibitors and treatment conditions.

Specific inhibitors of cellular protein tyrosine kinases (genistein; Sigma Chemical Co., St. Louis, MO), of EGFR PTK (tyrphostin 1; Sigma), and FGFR PTK (SU4989 and SU5402; Calbiochem, La Jolla, CA), were dissolved in dimethylsulphoxide (DMSO), and stock solutions were stored at 4°C and diluted in LMDM prior to use in experiments. Cells were either mock-treated or treated with various concentrations of these compounds separately for 2 hrs at 37°C. Following treatments, cells were washed twice with PBS and were either mock-infected or infected with the recombinant AAV vector as described above.

EXAMPLE 2 Successful Infection of Cells by AAV Requires a Cell Surface Co- Receptor All previously published studies have established that cell types that can bind

AAV can be infected by AAV (Qing et al, 1998, Summerford and Samulski, 1998, Ponnazhagan et al, 1996). For example, although the transduction efficiency varies greatly, permissive human cells, such as HeLa, KB, and 293, can bind AAV, but non- permissive cells, such as M07e, can not (FIG. IA). Interestingly, however, the inventors noted that murine NLH3T3 cells could also bind AAV efficiently, but could not be transduced by a recombinant AAV vector containing the cytomegalovirus immediate-early promoter-driven b-galactosidase gene (vCMVp-/αcZ) (FIG. IB-FIG. IE). Since the efficiency of AAV-mediated transgene expression in various cell types is dependent upon the phosphorylation status of the cellular ssD-BP (Qing et al, 1998), the inventors performed transduction studies, under identical conditions, with HeLa and NLH3T3 cells, with or without prior treatment with tyφhostin 1, previously shown to augment AAV-mediated transgene expression (Mah et al, 1998). These results are depicted in FIG. IB-FIG. IE. As can be seen, whereas the low-level of transgene expression in untreated HeLa cells (FIG. IB) could be significantly increased following treatment with tyφhostin 1 (FIG. 1C), as observed previously (Mah et al, 1998), transgene expression could not be detected in NLH3T3 cells (FIG. ID), and tyφhostin 1 treatment failed to elicit a significant response in these cells (FIG. IE). The lack of this response in NLH3T3 cells was not due the failure of tyφhostin 1 treatment to catalyze dephosphorylation of the ssD-BP since in both cell types, predominantly the dephosphorylated form of the ssD-BP was present following treatment with tyφhostin 1, as detected by electrophoretic mobility-shift assays (EMSA) (Qing et al, 1997, Qing et al, 1998). These results led the inventors to hypothesize that following initial attachment of AAV to the cell surface via the HSPG receptor, efficient entry of the virus requires the presence of a putative cellular co- receptor.

EXAMPLE 3 Fibroblast Growth Factor Receptor 1 (FGFRl) is Required for AAV

Binding Given the fact that HSPG is not sufficient for AAV entry into a cell, the inventors began the search for the co-receptor required for AAV infection. The inventors reasoned that AAV might utilize FGFR as a co-receptor for entry into the host cell. To this end, M07e cells, known to be non-permissive for AAV infection (Ponnazhagan et al, 1996), were stably transfected with the following expression plasmids, either alone, or in combination: murine (mu) HSPG; and human (hu) FGFRl. An additional human lymphoblastoid cell line, Raji, known to be negative for cell surface expression both of HSPG and FGFR (Lebakken and Rapraeger, 1996, Kiefer et al, 1990), was also stably transfected with muHSPG, huFGFRl, or both. Mock-transfected and three individual clones each from M07e and Raji cells were analyzed separately for binding of ¹²⁵I-bFGF and ³⁵S-AAV as previously described (Qing et al, 1998, Mah et al, 1998, Kan et al, 1993). These results are shown in FIG. 2A and FIG. 2B. It is interesting to note that M07e cells, known to lack HSPG expression (Barlett and Samulski, 1998), fail to bind bFGF, but following stable transfection with muHSPG cDNA, allow significant binding of bFGF. A low-level of bFGF binding also occurs in M07e cells stably transfected with huFGFR 1 cDNA alone, the extent of which is significantly higher when M07e cells co-express HSPG and FGFRl (FIG. 2A). These results suggest that M07e cells do indeed express the endogenous FGFR gene. Mock-tranfected Raji cells also fail to bind bFGF, as expected, and only low-levels of bFGF binding are detected in Raji cells stably transfected with either the HSPG or the FGFRl expression plasmid alone. In Raji cells that co-express HSPG+FGFR1, significant binding of bFGF occurs further corroborating the requirement of both HSPG and FGFRl for the ligand binding. It also is interesting that the binding patterns of radiolabled AAV to these two cell types closely resemble that of bFGF binding (FIG. 2B). Taken together, these data strongly suggest that cell surface expression both of HSPG and FGFRl is required for successful binding of AAV to the host cell.

EXAMPLE 4

Cell Surface Co-expression of HSPG and FGFRl Confers AAV Infectivity to Non-permissive Cells.

It was next of interest to examine whether M07e and Raji cells stably transfected with HSPG, or FGFRl, or both, could be successfully transduced with the recombinant vCMVp-ZαcZ vector. Individual clonal isolates from both cell types were either mock-infected or infected with vCMVp-ZαcZ under identical conditions and analyzed for transgene expression by fluorescence-activated cell sorting (FACS). Representative histograms of each of these clones are shown in FIG. 3A-FIG. 3H.

It is evident that, whereas little transgene expression occurred in mock- infected M07e cells as expected, M07e cells expressing either HSPG alone, or co- expressing HSPG+FGFR1, but not FGFRl alone, could be readily transduced by the recombinant AAV vector (FIG. 3A-FIG. 3D). Because M07e cells express the endogenous FGFR gene, expression of the exogenous HSPG is sufficient to render these cells permissive to AAV infection. Raji cells, on the other hand, fail to allow AAV-mediated transduction if only the exogenous HSPG or FGFRl genes are expressed, but co-expression of HSPG+FGFR1 genes confers, albeit at a relatively low-efficiency, AAV infectivity to these cells (FIG. 3E-FIG. 3H). The underlying mechanism of low-efficiency of transduction in Raji cells was investigated further by examining the extent of the viral DNA entry as described in Methods. It is evident that despite similar levels of viral binding (FIG. 2B), the extent of the viral DNA entry into Raji cells co-expressing HSPG+FGFR1 was significantly lower than that in M07e cells which correlated well with AAV transduction efficiencies in the two cell types. Additional individual clonal isolates from both cell types were also evaluated for AAV transduction efficiency. The cumulative data are presented in Table 3. It is evident that M07e and Raji cell clones co-expressing FGFRl+HSPG are transduced at an average transduction efficiency of approximately 70% and 10%, respectively. Taken together, these studies establish that co-expression of HSPG+FGFR1 is required not only for binding to, but also for entry of, AAV into the host cell.

Table 3. Effect of stable transfection of M07e and Raji cells with the various indicated expression plasmid DNAs on AAV-mediated transgene expression.

EXAMPLE 5

AAV-mediated Transgene Expression Requires

Dephosphorylation of the Cellular ssD-BP.

The inventors have recently provided evidence that a host cell protein, designated the single-stranded D-sequence-binding protein (ssD-BP), is a crucial determinant of AAV transduction efficiency (Qing et al, 1997; Qing et al, 1998).

The inventors have also determined that the ssD-BP is phosphorylated at tyrosine residues by the protein tyrosine kinase (PTK) activity of the cellular epidermal growth factor receptor (EGFR) since treatment of cells with tyφhostins, specific inhibitors of the EGFR PTK, causes dephosphorylation of the ssD-BP and leads to significant augmentation in AAV-mediated, post-receptor transgene expression (Mah et al,

1998). In order to evaluate whether the same mechanism was operational in M07e and Raji cells, these cell types stably co-transfected with HSPG and FGFRl expression plasmids were either mock-infected, or infected with the recombinant vCMVp-ZαcZ vector, either in the presence of co-infection with human adenovirus 2 (Ad2), or with prior treatment with tyφhostin 1, as previously described (Mah et al, 1998) since the ssD-BP in both cell types is present predominantly in the phosphorylated state and AAV-mediated transduction efficiency is approximately 2- 3%. Transgene expression was analyzed by FACS as described above. These results are shown in FIG. 4A-FIG. 4F. It is interesting to note that whereas little transgene expression occurred in mock-infected M07e (FIG. 4 A) and Raji (FIG. 4D) cells, as expected, each of the cell types co-expressing HSPG+FGFR1 exhibited roughly the same efficiency of transgene expression either in the presence of Ad2 or with prior treatment with tyφhostin 1. These studies were extended to include additional individual clonal isolates from both cell types. The cumulative data, presented in Table 4, further corroborate that post-receptor entry, dephosphorylation of the ssD-BP is necessary to allow AAV-mediated transgene expression.

Table 4. Relative effects of co-infection with human adenovirus 2 or treatment with Tyφhostin 1 on AAV-mediated transgene expression in M07e and Raji cell clones stably co-transfected with muHSPG+huFGFRl expression plasmid DNAs.

EXAMPLE 6

FGFR Autophosphorylation is not

Required for AAV-mediated Transduction

Since ligand binding to FGFR leads to receptor dimerization followed by receptor autophosphorylation leading to recruitment of intracellular signaling molecules (Rapraeger et al, 1991, Ledoux et al, 1992, Roghani and Moscatelli, 1992, Givol and Yayon, 1992, Kan et al, 1993), it was next of interest to determine whether the FGFR-associated protein tyrosine kinase (PTK) activity affected AAV-mediated transgene expression. Human 293 and HeLa cells, known to be permissive for AAV infection, were either mock-treated, or first treated with specific inhibitors of FGFR PTK activity (Strawn et al, 1996, Mohammadi et al, 1997) followed by infection with the recombinant vCMVp-ZαcZ vector under identical conditions and the extent of transgene expression was determined 48 hours post infection as described above. The results of these studies indicated that none of the FGFR PTK inhibitors had any significant effect on AAV-mediated transgene expression. The inventors conclude from these studies that FGFR PTK activity is not required for AAV-mediated transgene expression.

EXAMPLE 7 FGF Treatment Perturbs AAV Binding to Non-permissive and Permissive

Cells and Abrogates Viral entry into Permissive Cells.

In order to further corroborate the involvement of FGFRl as a co-receptor for AAV binding and/or entry, the inventors reasoned that treatment of non-permissive cells, such as NLH3T3 cells, and permissive cells, such as 293 cells, with large excess of bFGF during AAV infection would perturb AAV binding and infection, respectively. To this end, the following two sets of studies were carried out. In the first set, binding studies were carried out with radiolabeled AAV using NLH3T3 and 293 cells in the absence or presence of large excess of bFGF. Several additional controls that included unlabeled wt AAV, or heparin (as positive controls), and EGF (as a negative control), were also included. The results of such a study are shown in FIGS. 6- A and 6-B. It is evident that AAV binding to NLH3T3 cells was inhibited by heparin, as expected (Summerford and Samulski, 1998), bFGF also inhibited AAV binding to a significant extent, whereas EGF had no effect under identical conditions. Similarly, unlabeled wt AAV significantly inhibited binding of radiolabeled AAV to 293 cells, as expected. AAV binding to 293 cells was also reduced in the presence of bFGF. Similar concentrations of EGF, on the other hand, had no significant effect on AAV binding to 293 cells. In the second set of studies, equivalent numbers of 293 cells were transduced with the recombinant vCMVp-ZαcZ vector either in the absence or presence of large excess of bFGF or EGF under identical conditions. Transgene expression was evaluated 48 h post-transduction by X-gal staining as previously described (Ponnazhagan et al, 1997). The results of these studies are shown in FIG. 5C-FIG. 5H. It was determined that AAV-mediated transduction of 293 cells (FIG. 5C) was inhibited by approximately 89% in the presence of bFGF (FIG. 5E), but only by approximately 2% in the presence of EGF (FIG. 5G). These assays, carried out with 293 cells with prior treatment with genistein (FIG. 5D, FIG. 5F and FIG. 5H) a specific inhibitor of cellular protein tyrosine kinases, known to augment AAV transduction efficiency (Qing et al, 1997), yielded similar results (-89% inhibition with bFGF; 0% inhibition with EGF) indicating that lack of transgene expression in the presence of bFGF (FIG. 5F) was not due to phosphorylation of the ssD-BP in 293 cells. Taken together, these results firmly establish that the HSPG-FGFR1 interaction is crucial not only for successful binding, but also for entry of AAV into cells.

EXAMPLE 8 AAV Co-receptor Activity of FGFRl, FGFR2, FGFR3, and FGFR4. Experiments in previous examples were carried out with the FGFRl cDNA under the control of the SV40 promoter. There are at least three additional distinct but related members in the FGFR family, viz. FGFR2, FGFR3, and FGFR4 (Hughes, 1997), which are differentially expressed in primary human tissues. FGFRl is expressed abundantly in brain neurons and cardiac myocytes, whereas FGFR2 expression predominates in the choroid plexus and glial cells. FGFR3 expression abounds in the intestine and growth plates, and FGFR4 is expressed in hepatocytes and the adrenal glands (Gonzalez et al, 1996; Ozawa et al, 1996; Olwin et al, 1989). The amino acid sequence within the intracellular kinase domain is highly variable among the different FGFRs (14-79% homology), and perhaps accounts for their different signaling and mitogenic potentials (Wang et al, 1994). The inventors obtained FGFRl, FGFR2, FGFR3, and FGFR4 cDNA expression plasmids, each under the control of the CMV promoter, from Dr. Dan Donoghue, University of California, San Diego. Each of the plasmids was transfected into control and HSPG- expressing Raji cells, and clonal populations were analyzed for the various types of FGFRs for their potential co-receptor activity for AAV-mediated transduction. These results are shown in Figure 7. FGFRl possesses the highest activity, followed by FGFR2 and FGFR3. In these experiments, the inventors were not able to detect any co-receptor activity with FGFR4.

All of the compositions and/or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and/or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. More specifically, it will be apparent that certain agents which are both chemically and physiologically related may be substituted for the agents described herein while the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.

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Claims

CLAIMS;

1. A method of increasing AAV infection of a cell comprising increasing the amount of fibroblast growth factor receptor (FGFR) on the surface of said cell wherein the increased FGFR increases the AAV uptake by said cell.

2. The method of claim 1, further comprising contacting said cell with an AAV vector.

3. The method of claim 1 , wherein increasing the amount of said FGFR of said cell comprises providing to said cell an expression construct comprising a polynucleotide encoding an FGFR polypeptide and a promoter active in eukaryotic cells, said polynucleotide being operably linked to said promoter.

4. The method of claim 1, further comprising increasing the amount of cell surface heparan sulphate proteoglycan (HSPG) on said cell.

5. The method of claim 1, wherein increasing said HSPG of said cell comprises providing to said cell an expression construct comprising a polynucleotide that encodes an HSPG polypeptide and a promoter active in eukaryotic cells, said polynucleotide being operably linked to said promoter.

6. The method of claim 2, wherein said AAV is a vector comprising an expression cassette comprising a selected polynucleotide and a promoter active in eukaryotic cells, wherein said polynucleotide is operably linked to said promoter.

7. The method of claim 6, wherein said selected polynucleotide encodes a polypeptide.

8. The method of claim 6, wherein said selected polynucleotide encodes an antisense construct.

9. The method of claim 6, wherein said selected polynucleotide encodes a ribozyme.

10. The method of claim 3, wherein, said promoter is an inducible promoter.

11. The method of claim 3, wherein said promoter is CMV LE, SV40 LE, HSV tk, β-actin, human globin α, human globin β, human globin γ, RSV, B19p6, alpha-1 antitrypsin, PGK, tetracyclin, MMTV or albumin promoter.

12. The method of claim 3, wherein said expression cassette further comprises a polyadenylation signal.

13. The method of claim 12, wherein said polyadenylation signal is an AAV polyadenylation signal, an SV40 polyadenylation signal or a BGH polyadenylation signal.

14. The method of claim 7, wherein polypeptide is a hormone, a tumor suppressor, an inhibitor of apoptosis, a toxin, a lymphokine, a growth factor, an enzyme, a DNA binding protein or a single-chain antibody.

15. The method of claim 5, wherein, said promoter is an inducible promoter.

16. The method of claim 5, wherein said promoter is CMV IE, SV40 LE, HSV tk, β-actin, human globin α, human globin β, human globin γ, RSV, B19p6, alpha-1 antitrypsin, PGK, tetracyclin, MMTV or albumin promoter.

17. The method of claim 5, wherein said expression cassette further comprises a polyadenylation signal.

18. The method of claim 17, wherein said polyadenylation signal is an AAV polyadenylation signal, an SV40 polyadenylation signal or a BGH polyadenylation signal.

19. The method of claim 5, wherein said expression construct is a viral vector.

20. The method of claim 19, wherein said viral vector is selected from the group consisting of retrovirus, adenovirus, vaccinia virus, heφesvirus and adeno-associated virus.

21. The method of claim 6, wherein said promoter is an inducible promoter.

22. The method of claim 6, wherein said promoter is CMV LE, SV40 IE, HSV tk, β-actin, human globin α, human globin β, human globin γ, RSV, B19p6, alpha-1 antitrypsin, PGK, tetracyclin, MMTV or albumin promoter.

23. The method of claim 6, wherein said expression cassette further comprises a polyadenylation signal.

24. The method of claim 17, wherein said polyadenylation signal is an AAV polyadenylation signal, an SV40 polyadenylation signal or a BGH polyadenylation signal.

25. A method of expressing a selected polynucleotide from an adeno-associated viral (AAV) vector in a host cell comprising the steps of:

(i) providing an AAV vector comprising an expression cassette comprising said selected polynucleotide and a promoter active in eukaryotic cells, wherein said selected polynucleotide is operably linked to said promoter;

(ii) contacting said vector with said host cell under conditions permitting uptake of said vector by said host cell; and (iii) increasing the amount of fibroblast growth factor receptor (FGFR) on the surface of said cell;

wherein the increased FGFR increases the uptake of AAV by said cell.

26. The method of claim 25, wherein increasing said FGFR of said cell comprises providing to said cell an expression construct comprising a polynucleotide encoding an FGFR polypeptide and a promoter active in eukaryotic cells, said polynucleotide being operably linked to said promoter.

27. The method of claim 25, further comprising increasing the amount of cell surface heparan sulphate proteoglycan (HSPG) in said cell.

28. The method of claim 25, wherein increasing said HSPG of said cell comprises providing to said cell an expression construct comprising a polynucleotide that encodes an HSPG polypeptide and a promoter active in eukaryotic cells, said polynucleotide being operably linked to said promoter.

29. The method of claim 28 wherein said HSPG encoding polynucleotide and said

FGFR encoding polynucleotide are in the same expression construct.

30. The method of claim 28, wherein said HSPG encoding polynucleotide and said FGFR encoding polynucleotide are separated by an LRES.

31. The method of claim 28, wherein said HSPG encoding polynucleotide and said FGFR encoding polynucleotide are each under the control of a separate promoter operative in eukaryotic cells.

32. The method of claim 25, wherein said host cell is an erythroid cell.

33. The method of claim 25, wherein said erythroid cell is a human erythroid cell.

34. The method of claim 25, wherein said host cell is selected from the group consisting of a bone marrow cell, a peripheral blood cell, a lung cell, a gastrointestinal cell, an endothelial cell and myocardial cell.

35. The method of claim 25, wherein said host cell is in an animal.

36. The method of claim 25, further comprising inhibiting the function of D sequence binding protein (D-BP) in said host cell.

37. The method of claim 36, wherein said inhibiting comprises reducing the expression of D-BP in said host cell.

38. The method of claim 37, wherein reducing the expression of D-BP is achieved by contacting the host cell with an antisense D-BP polynucleotide.

39. The method of claim 38, wherein said antisense D-BP polynucleotide targets a translational start site.

40. The method of claim 38, wherein said antisense D-BP polynucleotide targets a splice-junction site.

41. The method of claim 36, wherein the agent that reduces the expression of D- BP is an antibody or a small molecule inhibitor.

42. The method of claim 41, wherein the antibody is a single chain antibody.

43. The method of claim 41, wherein said antibody is a monoclonal antibody.

44. The method of claim 36, wherein said inhibiting comprise reducing the D sequence binding activity of said D-BP in said host cell.

45. The method of claim 44, wherein reducing the binding activity is achieved by inhibiting the tyrosine phosphorylation of D-BP.

46. The method of claim 45, wherein inhibiting the phosphorylation is achieved by contacting said host cell with a D-BP peptide containing a tyrosine residue.

47. The method of claim 45, wherein inhibiting the phosphorylation is achieved by contacting said host cell with an agent that inhibits tyrosine kinase.

48. The method of claim 47, wherein said tyrosine kinase is an EGF-R tyrosine kinase.

49. The method of claim 48, wherein said agent is an inhibitor of EGF-R that reduces the expression of EGF-R protein kinase.

50. The method of claim 48, wherein the inhibitor of EGF-R protein kinase is an agent that binds to and inactivates EGF-R protein kinase.

51. The method of claim 48, wherein the inhibitor of EGF-R protein kinase inhibits the interaction of EGF-R with a D-BP.

52. The method of claim 50, wherein the agent that reduces the expression of EGF-R protein kinase is an antisense construct.

53. The method of claim 50, wherein the agent that binds to and inactivates EGF-

R protein kinase is an antibody or a small molecule inhibitor.

54. The method of claim 53, wherein the antibody is a single chain antibody.

55. The method of claim 53, wherein said antibody is a monoclonal antibody.

56. The method of claim 47, wherein said agent is selected from the group consisting of hydroxyurea, genistein, tyφhostin 1, tyφhostin 23, tyφhostin 63, tyφhostin 25, tyφhostin 46, and tyφhostin 47.

57. A method for providing a therapeutic polypeptide to a cell comprising the steps of:

(i) providing an AAV vector comprising an expression construct comprising said a polynucleotide that encodes said polypeptide and a promoter active in eukaryotic cells, wherein said polynucleotide is operably linked to said promoter;

(ii) contacting said vector with said cell under conditions permitting uptake of said vector by said cell; and

(iii) increasing the amount of fibroblast growth factor receptor (FGFR) on the surface of said cell;

wherein said increase in FGFR results in an increase in the uptake of said vector by said cell.

58. The method of claim 57, wherein said therapeutic polypeptide is a hormone, a tumor suppressor, an inhibitor of apoptosis, a toxin, a lymphokine, a growth factor, an enzyme, a DNA binding protein or a single-chain antibody.

59. The method of claim 57, wherein said cell is located within a mammal.

60. The method of claim 59, wherein said cell is a cancer cell.

61. The method of claim 60, wherein said cancer cell is selected from the group consisting of lung, breast, melanoma, colon, renal, testicular, ovarian, lung, prostate, hepatic, germ cancer, epithelial, prostate, head and neck, pancreatic cancer, glioblastoma, astrocytoma, oligodendroglioma, ependymomas, neurofibrosarcoma, meningia, liver, spleen, lymph node, small intestine, blood cells, colon, stomach, thyroid, endometrium, prostate, skin, esophagus, bone marrow and blood.

62. An adenoassociated viral expression construct comprising:

(a) a first polynucleotide encoding a selected gene and a first promoter functional in eukaryotic cells wherein said polynucleotide is under transcriptional control of said first promoter; and

(b) a second polynucleotide encoding an FGFR.

63. The expression construct of claim 62, further comprising a third polynucleotide encoding an HSPG polypeptide.

64. The expression construct of claim 62, wherein said FGFR encoding polynucleotide is under the control of said first promoter.

65. The expression construct of claim 62, wherein said first polynucleotide and said second polynucleotide are separated by an LRES.

66. The expression construct of claim 62, wherein said second polynucleotide is under the control of a second promoter operative in eukaryotic cells.

67. The expression construct of claim 62, wherein said selected gene encodes a protein selected from the group consisting of a tumor suppressor, a cytokine, a receptor, inducer of apoptosis, and differentiating agents.

68. The expression construct of claim 67, wherein said tumor suppressor is selected from the group consisting of p53, pi 6, p21, MMAC1, p73, zacl, C- CAM, BRCAI and Rb.

69. The expression construct of claim 67, wherein said inducer of apoptosis is selected from the group consisting of Harakiri, Ad E1B and an ICE-CED3 protease.

70. The expression construct of claim 67, wherein said cytokine is selected from the group consisting of LL-2, IL-2, LL-3, LL-4, LL-5, LL-6, LL-7, LL-8, LL-9, LL- 10, LL-11, LL-12, LL-13, LL-14, LL-15, TNF, GMCSF, β-interferon and γ- interferon.

71. The expression construct of claim 67, wherein said receptor is selected from the group consisting of CFTR, EGFR, VEGFR, LL-2 receptor and the estrogen receptor.

72. A pharmaceutical composition comprising: (i) a first adenoassociated viral expression construct comprising a promoter functional in eukaryotic cells and a first polynucleotide encoding a selected polypeptide, wherein said first polynucleotide is under transcriptional control of said promoter; (ii) a second polynucleotide encoding an FGFR; and

(ii) a pharmaceutically acceptable buffer, solvent or diluent.

73. The pharmaceutical composition of claim 72, wherein said promoter is selected from the group consisting of CMV LE, SV40 LE, RSV, β-actin, tetracycline regulatable and ecdysone regulatable.

74. The pharmaceutical composition of claim 72, further comprising a second expression construct comprising a third polynucleotide encoding an HSPG polypeptide wherein said third polynucleotide operatively linked to a third promoter.