WO2000054595A1

WO2000054595A1 - Recombinant adeno-associated virus transfer of genes affecting demyelination

Info

Publication number: WO2000054595A1
Application number: PCT/US2000/006839
Authority: WO
Inventors: John Guy; Xiaoping Qi; William W. Hauswirth
Original assignee: John Guy; Xiaoping Qi; Hauswirth William W
Priority date: 1999-03-15
Filing date: 2000-03-15
Publication date: 2000-09-21
Also published as: AU3629200A; EP1162887A1; EP1162887A4; CA2367648A1

Abstract

Disclosed are methods for the use of recombinant adeno-associated virus compositions. In particular, the use of catalase- or superoxide dismutase-expressing rAAV constructs in compositions for delivery to the optic nerve is disclosed. Also disclosed are methods for the treatment and amelioration of symptoms of demyelinating disorders of an animal, such as multiple sclerosis, allergic encephaloneuritis and optic neuritis.

Description

RECOMBINANT ADENO-ASSOCIATED VIRUS TRANSFER OF GENES AFFECTING DEMYELINATION

DESCRIPTION

1.0 BACKGROUND OF THE INVENTION

The United States government has certain rights in the present invention pursuant to Grant Numbers EY-07982, EY-11123, and EY-07864 from the National Institutes of Health.

1.1 FIELD OF THE INVENTION The present invention relates generally to the fields of molecular biology and virology, and in particular, to methods for using recombinant adeno-associated virus compositions that express superoxide dismutase or catalase-encoding DNA segments in the treatment of demyelinating disorders of the nervous system and most particularly in the optic nerve. In certain embodiments, the invention concerns the use of rAAV in a variety of investigative, diagnostic and therapeutic regimens. Methods are also provided for preparing rAAVs that express superoxide dismutase or catalase-encoding gene segments for use in such therapies.

1.2 DESCRIPTION OF THE RELATED ART

A variety of demyelinating disorders affect countless patients each year worldwide. One of these is multiple sclerosis (MS) which affects approximately one million people. The socioeconomic impact is substantial. In a single year, 75% to 85% of MS patients were unemployed with estimated costs of patient care and lost income of approximately $10 billion. Current therapeutic strategies for MS include (Ruuls et al, 1995) nonspecific immunosuppressive drugs (corticosteroids, methotrexate), (Brett and Rumsby, 1993) reduction of lymphocyte trafficking (interferons), and (Guy et al., 1993) inhibition of lymphocyte receptor peptide and induction of anergy (copolymer). Interferons and copolymer must be given one to several times per week. Unfortunately, these agents have many side effects and in many cases are not effective therapy. 1.2.1 EXPERIMENTAL ALLERGIC ENCEPHALOMYELITIS

Experimental allergic encephalomyelitis (EAE) is an inflammatory autoimmune disorder of primary central nervous system demyelination that is recognized as an animal model for the human disease multiple sclerosis (MS) (Raine, 1985; Paterson and Day, 1982). The optic nerve is a frequent site of involvement in EAE and MS (Rao, 1981; Beck et al, 1992; Rizzo and Lessell, 1988). In both disorders, myelin-forming oligodendroglia are the primary targets of immune-mediated injury (Raine, 1985; Steinman, 1991; Raine, 1997), although other cell types are affected also. Demyelinated axons exhibit hydropic degeneration with dissolution of microtubules and neurofilaments. Even endothelial cells that appear ultrastructurally intact lose their ability to maintain the integrity of the blood-brain barrier (BBB) (Lossinsky et al, 1989). Consequently, treatments for EAE, and eventually MS, must protect not only oligodendroglia, but also axons and endothelial cells against structural and functional mediators of tissue injury.

Reactive oxygen species (ROS) such as superoxide and nitric oxide (NO), released by inflammatory cells, are mediators of demyelination and disruption of the BBB in EAE (Honegger et al, 1989; Guy et al, 1989a). The role of ROS in altering BBB permeability and demyelination has been inferred from the beneficial effect of free radical scavengers and antioxidants on the neurologic deficits and histopathologic lesions associated with EAE (Guy et al, 1989b; Bowern et al, 1984). ROS scavengers include catalase and superoxide dismutase. Superoxide dismutase dismutes superoxide to hydrogen peroxide (H₂O ) and catalase detoxifies the H O₂ to H₂O and O . Exogenous catalase has been previously shown to reduce disruption of the BBB and demyelination of the optic nerve in EAE (Guy et al, 1989a; Guy et al, 1989b).

Limitations to the use of catalase protein are several fold. First, catalase must be administered daily, even when conjugated to polyethylene glycol, to prolong the half life of the enzyme (Abuchowski et al, 1977; Guy et al, 1994b). Second, exogenous catalase is effective only during the periods of active BBB disruption when this high molecular weight protein is able to penetrate the central nervous system (CNS). Third, optic neuritis recurs in part due to the inability of the catalase protein to cross the BBB after integrity is restored by the catalase- mediated detoxification of H₂O . 1.2.2 OXIDANTS

Oxidants play an important role in the pathogenesis of many lung diseases (Kinnula et al. 1995). The least equivocal example of oxidant-mediated lung injury in humans is the acute lung injury resulting from prolonged exposure to elevated levels of O , a frequent and important clinical problem. At oxygen concentrations exceeding a fraction of inspired oxygen (FiO₂) of 0.5 (at 1.0 ami), the likelihood of developing pulmonary oxygen toxicity is accelerated (Warren and Ward, 1997). Critical mechanisms of hyperoxia toxicity include the increased production of superoxide anion, hydrogen peroxide, and other activated species that overwhelm antioxidant defenses in both lung endothelial and epithelial cells (Schraufstatter and Cochrane, 1997). Free radical-mediated injury is also a major cause of damage occurring in ischemic tissue after reperfusion (Heffher and Fracica, 1996). Ischemia-reperfusion injury has been reported after reexpansion of atelectatic lung, reperfusion of a mechanically occluded pulmonary artery, and lung transplantation (in which context poor tolerance to ischemia-reperfusion remains a major limitation) (Sarris et al, 1994). The central mechanism in ischemia-reperfusion lung injury involves neutrophil-endothelium interaction, with highly reactive free radicals generated from various sources in the reperfused tissues, including activated polymorphonuclear leukocytes and the xanthine oxidase system (Heffner and Fracica, 1996).

Although the regulatory mechanisms and details of the balance of antioxidant defense barriers need to be further elucidated, a critical role for free radical-scavenging enzymes in cellular protection against oxidant stress is generally accepted (Tanswell and Freeman, 1987). Superoxide dismutase (SOD) and catalase, the major intracellular antioxidant enzymes, cooperate in the detoxification of free oxygen radicals produced during normal aerobic respiration. Mitochondrial Mn-SOD and cytosolic CuZn-SOD are responsible for the dismutation of superoxide O₂ ^~ in H₂O . The peroxide-scavenging intracellular enzyme catalase rapidly degrades H₂O₂ to water and molecular oxygen. The importance of intracellular antioxidants to prevent oxidant injury has been most clearly shown in transgenic mice overexpressing SOD, which are protected against hyperoxia, indicating that an increase in intracellular levels of antioxidant enzymes protects against oxidant injury (Wispe et al, 1992).

In this context, therapeutic approaches designed to deliver SOD or catalase to these intracellular sites at sustained levels, would, therefore, be extremely advantageous. A number of approaches involving in vivo administration of SOD and/or catalase have been used in attempts to prevent the toxic effect of oxygen on lungs, but with little success (Crapo et al, 1980; Padmanabhan et al, 1985). The current problems with antioxidant recombinant enzyme therapy include their short half-life in the bloodstream and their inability to penetrate cells and to ablate intracellular oxidative stress events. Attempts to increase the antioxidant enzyme half-life by polyethylene glycol conjugation or liposomes have improved antioxidant activity but have inherent limitations (Tanswell and Freeman, 1995; Walther etal, 1995).

Gene delivery and expression have been demonstrated in several mammalian tissues, including retina (Flannery et al., 1997), neural tissues (Peel et al, 1997), endothelial cells (Erzrum et al., 1993) and optic nerve (Cayouette and Gravel, 1996). A problem described in the report of gene transfer to the optic nerve is that only axons of the optic nerve and their cell bodies in the retina were labeled by the transferred reporter gene 22, whereas in experimental allergic encephalomyelitis and multiple sclerosis, oligodendroglia and endothelia are the targets of mediators of inflammation; thus, for neuroprotection of the optic nerve, the genes that encode for defenses against reactive oxygen species must be transferred to oligodendroglia or endothelia cell types.

1.3 DEFICIENCIES IN THE PRIOR ART

Currently, there are limited pharmacological approaches to treating demyelinating disorders and ameliorating the symptoms of such disorders in an affected animal. Many such methods introduce undesirable side effects, and do not overcome the problems associated with traditional modalities and treatment regimens for conditions such as optic neuritis, multiple sclerosis and the like. Thus, the need exists for an effective treatment that circumvents the adverse effects and provides more desirable results, with longer acting effects, and improved patient compliance. In addition, methods for delivery of oligonucleotides to a host cell that express a polypeptide useful in the amelioration of such conditions, and in particular, administration of specific adenoviral-based polynucleotide constructs to a mammal are particularly desirable.

2.0 SUMMARY OF THE INVENTION

The present invention addresses some of the limitations in the prior art by providing methods and compositions for ameloriation and treatment of effects associated with demyelinating disorders of the central nervous system; for example optic neuritis or allergic encephalomyelitis. The invention utilizes recombinant adeno-associated virus to deliver a therapeutic gene to transformed host cells, to protect such cells against the adverse effects of hydrogen peroxide. These effects include the classical demyelination and disruption of the blood brain barrier that are the hallmarks of many demyelating diseases. In exemplary embodiments the inventors have described the use of nucleic acid segments that encode polypeptides including, but not limited to, superoxide dismutase (SOD), catalase and the like.

Genetic augmentation of cellular defenses against ROS offers an approach to these problems. Viral-mediated gene delivery is becoming increasingly accepted as a promising way to deliver therapeutic genes (Mulligan, 1993; McLaughlin et al, 1988). In fact, two- to four-fold increases in catalase expression have been shown in vitro in human endothelial cells one day after administration of viral-catalase cDNA complexes (Erzurum et al, 1993). Moreover, the increased catalase levels persisted for one week, as opposed to exogenous administration that at best achieved a two-fold increase with repeated daily injections. The optic nerve is a frequent site of demyelination in both EAE and in MS. Additonally, the eye is known as a readily accessible site for gene transfer (Zolotukhin et al, 1996; Flannery et al, 1997). The present invention shows the successful viral-mediated gene transfer of catalase on suppression of EAE in the optic nerve.

Therefore, in part, the invention related to suppression of oxidative injury by employing viral-mediated transfer of the human genes that reduce levels of hydrogen peroxide or superoxide in the optic nerves in accepted in vivo models. The optic nerve is a frequent site of involvement common to both experimental allergic encephalomyelitis (EAE) and multiple sclerosis (MS). Catalase activity was increased approximately two-fold each in various cell types of the optic nerve. The catalase gene inoculation reduced demyelination by 38%, optic nerve head swelling by 29%, cellular infiltration by 34%, disruption of the BBB by 64%, and in vivo levels of H O₂ by 61%. Since the efficacy of potential treatments for MS are conventionally tested in the EAE animal model, the results strongly support use of a catalase or a superoxide dismutase (SOD) gene delivery system employing viral vectors as a therapeutic strategy for suppression of MS. The main advantage of such gene therapy with catalase, SOD or other oxidation suppressive genes is that after a single injection, the gene(s) are continuously produced in the cells of the nervous system, thereby providing long-term protection from the effects of reactive oxygen species or hydrogen peroxide released by inflammatory cells. Consequently, patients will require less frequent hospitalizations or additional treatments. Such treatment methods represent a marked improvement over the current strategies available to the clinician. In one embodiment, rAAV compositions comprise an rAAV that incorporates a polynucleotide sequence that encodes a polypeptide that expresses in a cell and reduces the level of harmful reactive oxygen species, particularly hydrogen peroxide and superoxide. Particularly effective antioxidants are human catalase and human superoxide dismutase (SOD) with MnSOD being particularly preferred. Naturally, the viral vectors including SOD or Cat genes need not incorporate the entire gene, but may include those segments that express effective amounts of the polypeptide in the cells to effectively scavenge reactive oxygen species. The viral vector compositions are used to deliver catalase or SOD to the optic nerve, resulting in prevention of optic nerve demyelation induced by hydrogen peroxide or superoxide. This has been demonstrated in in vivo models for EAE and optic neuritis.

The rAAV-Cat or rAAV-SOD vectors may transfect endothelial or oligodendroglial cells. The presence of catalase has also been demonstrated in astrocytes and microdendroglia as well as in axons. A preferred promoter is CMV; however, cell specific promoters for endothelial, oligodendroglial or neuronal cells are also contemplated. In particular, human myelin basic protein promoter will be useful. Other promoters include human platelet dervied growth factor promoter (PDGF) and human vascular endothelial growth factor (VEGF) promoter. Such promoters may be employed in a single vector that comprises Cat and/or SOD or in separate vectors.

A particularly preferred embodiment is the use of AV or rAAV vectors for simultaneous delivery of two different reactive oxygen species scavenger enzymes to the optic nerve. Scavenging of superoxide of superoxide by germ line gene expression increases in the ECSOD, and combined with scavenging of H2O2 by viral-mediated gene tranfer, demyelination of acute experimental allergic encephalomyelitis is decreased by at least 72%.

As part of the invention, several combinations of compositions comprising the rAAV vectors are envisioned, including rAAV-SOD vector and AV-Cat vector compositions. A particularly preferred combination is rAAV-MnSOD and AV-Cat. Alternatively, rAAV- MnSOD and rAAV-Cat may be employed.

In particular aspects, the recombinant vector compositions are useful in preventing and/or ameliorating demyelination in conditions such as allergic encephalomyelitis and optic neuritis. The experimental allergic encephalomyelitis animal (EAE) model is accepted as a relevant model for multiple sclerosis; thus the long-term expression of reactive oxygen species scavengers, as shown with catalase and SOD, will be effective in treatment regimens for human patients.

Kits are also contemplated as part of the invention. Such kits comprise rAAV compositions comprising a selected polynucleotide sequence encoding a mammalian catalase or superoxide dismutase polypeptide, a device for delivering the rAAV composition and instructions for use. Optionally, the kits may contain AV-Cat vector compositions in combination with the rAAV compositions.

3.0 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 the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements, and in which:

FIG. 1 is a restriction map of the rAAV-Cat construct;

FIG. 2A is a bar graph showing ∞2-fold increases in the mean number of catalase immunogold particles within astrocytes (astro), oligodendrocytes (oligo), microdendroglia (micro), axons, and endothelia (endo) with inoculations of rAAV-Cat;

FIG. 2B is a bar graph showing catalase inoculations had the following effect on EAE: reduced demyelination (increased myelin areas);

FIG. 2 C is a bar graph showing catalase inoculations had the following effect on EAE: reduced optic nerve head edema (smaller areas);

FIG. 2D is a bar graph showing catalase inoculations had the following effect on EAE: decreased optic nerve cell count;

FIG. 2E is a bar graph showing catalase inoculations had the following effect on EAE: reduced extravasated immunogold-labeled serum albumin (suppressed disruption of the BBB); FIG. 2F is a bar graph showing catalase inoculations had the following effect on EAE: reduced in vivo levels of H₂O₂ in the optic nerve head (ONH), retrobulbar optic nerve (RON) and the optic nerve sheath (ONS);

FIG. 3 is a restriction map of the rAAV-MnSOD construct.

FIG. 4 is a restriction map of the AV-cat construct

FIG. 5A is a bar graph showing approximately 2-fold increases in the mean number of catalase immunogold particles (AdCat) within astrocytes, ohgodendrocytes, microendroglia, axons and endothelia with inoculations of adenovirus and the catalase gene compared with controls.

FIG. 5B is a bar graph showing that CAT inoculations had reduced demyelation (increased myelin areas) on experimental allergic encephalomyelitis.

FIG. 5C is a bar graph showing that CAT inoculations effected reduced nerve head edema (smaller area).

FIG. 5D is a bar graph showing that CAT inoculations led to decreased optic nerve cell count.

FIG. 5E is a bar graph showing that CAT inoculations led to reduced extravasated immunogold-labeled serum albumin (suppressed disruption of the blood brain barrier).

FIG. 5F is a bar graph showing that CAT inoculations reduced in vivo levels of hydrogen peroxide in the nerve head, retrobulbar optic nerve and the optic nerve sheath.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

4.0 DETAILED DESCRIPTION OF THE INVENTION Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as treatment regimens adapted to particular types of disease conditions or appropriate adaptations to different age groups which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

4.1 Optic Neuritis

Viral-mediated gene transfer offers novel and effective treatment regimens of potentially therapeutic proteins to humans. The examples described here employ two different approaches; one by injection into the eye and the other into the brain. The introduction of transduced proteins into the optic nerve presented a challenge because, unlike glial cells, the cell bodies of axons that comprise the nerve do not reside within the nerve itself, but in the retina. Since axons of the optic nerve do not have the organelles necessary for protein synthesis, transcription and translation of introduced DNA must occur in retinal ganglion cells.

RT-PCR was used to show that ganglion cells were directly infected by the recombinant virus. While most cells exhibited both the brown mRNA reaction product and blue lacZ protein, thereby indicating transcription of the transgene and translation of the transgene protein, respectively, it was apparent that some cells expressed only the mRNA. This indicated that they were recently transfected, but as yet not translating detectable amounts of the lacZ protein. More important, the brown mRNA reaction product within transduced ganglion cells made it highly unlikely that substantial amounts of the blue β-galactosidase protein were transferred to ganglion cells from other cell types. Therefore, the blue labeling of the optic nerve head was most likely due to the orthograde axonal transport of β-galactosidase from retinal ganglion cells, also indicating that most blue cells in the ganglion cell layer were retinal ganglion cells and not displaced amacrine cells.

The observation of reporter gene mRNA in ganglion cells with transport of the resultant protein to the optic nerve head and retrobulbar nerve, the foci most frequently affected by the demyelinating inflammation of both experimental allergic encephalomyelitis and multiple sclerosis, the disc edema of anterior ischemic optic neuropathy, and Leber hereditary optic neuropathy, indicated the feasibility of therapeutic gene transfer to the optic nerve.

Transduction of the cell type(s) affected by the disease process is a common prerequisite for potentially therapeutic gene transfers. For this reason the CMV promoter was selected since it is well known for its potential to drive gene expression in heterogeneous cell types. This promoter supported cellular expression of β-galactosidase in axons, glia, and endothelia of the optic nerve; however, adenoviral and β-actin promoters may also be used to drive expression. While a general promoter for transgene expression in different cell types was employed, cell- specific promoters may have an advantage over the CMV promoter by inducing a higher efficiency of transduction in targeted cells. Several examples of cell-specific promoters are known, including the opsin promoter to drive expression exclusively in photoreceptors of the retina with a high rate of efficiency (Flannery et al, 1997). In comparison, using a CMV promoter to drive expression of hgφ, a much lower rate of transduction efficiency in these same cells has been observed (Ali et al., 1996). Another example is the use of neuronal promoters (neuron-specific enolase or platelet-derived growth factor) which drive expression of hgφ in spinal neurons, but not in astroglial cells (Peel et al., 1997). The CMV promoter is preferred for transduction of the heterogeneous optic nerve cell population that is affected by the demyelinating inflammation of experimental allergic encephalomyelitis.

The choice of vector for gene delivery is important, particularly when gene therapy is to be applied to the treatment of human optic neuropathies. For transduction of the mammalian optic nerve, the vector must be capable either of incorporating the designated cDNA into the host genome without the need for cell replication, as cell division is limited in the mammalian optic nerve, or of creating a stable episomal state. While AAV is capable of meeting both these requirements, adenovirus is capable of replication that may be a cause for concern. Thus far AV and AAV are the only two vectors that have been described for gene delivery to the optic nerve. Any vector associated with treatment regimens for humans must be nonpathogenic. The host inflammatory response generated by adenovirus in ocular tissues is particularly well recognized (Hoffman et al, 1997) Unlike adenovirus, AAV is nonpathogenic and does not incite an ocular inflammatory response (Muzyczka, 1992). This is an important consideration in studying the effects of gene therapy on an in vivo inflammatory models of optic nerve demyelination such as experimental allergic encephalomyelitis. For therapeutic efficacy, cellular expression of the transgene protein must persist for the duration of the disease process and perhaps longer to reduce recurrences that occur in optic neuritis and multiple sclerosis. The results described show detection of β-galactosidase after one year. Control experiments with the β-galactosidase antibody preabsorbed with the β- galactosidase protein confirmed that the immunogold labeling detected one year after injection was specific for β-galactosidase, thereby proving continued transduction of the transferred lacZ gene even though transcription of mRNA was not confirmed by RT-PCR at this later time point.

On the other hand, long-term studies with adenoviral vectors show that lacZ is undetectable 2 months after injection into skeletal muscle but may persist longer in the eyes of animals with defective immune systems (Kessler et al, 1996). In contrast, long-term expression of rAAV-transferred genes has been demonstrated in various tissues such as brain (3-4 months) (Kaplitt et al, 1994) and muscle (40 weeks to 1 years) (Xiao et al., 1996). In these studies, protein expression began to diminish after approximately three months. Similarly, transduction in the optic nerve with rAAV persists one year after a single injection of the viral cDNA complexes. RT-PCR results show the absence of the brown mRNA reaction product in some of the cells that contained only the blue lacZ reaction product suggesting that the transgene gene in these cells was turned off, and is no longer producing mRNA. This finding at the earlier time point helps to explain the reductions in the levels of tissue expression of lacZ seen one year after injection, as β-galactosidase has a short half-life and would not be expected to persist for long periods in cells that are no longer transcribing lacZ mRNA.

4.2 Optic Nerve Cellular Structure

The cellular structure of the optic nerve consists of myelin-forming oligodendroglia, astrocytes, microglia, endothelia, and axons. Oligodendroglia are the cell type most vulnerable to immune-mediated injury in experimental allergic encephalomyelitis, an animal model of multiple sclerosis; however, demyelinated optic nerve fibers are also affected. They exhibit hydropic degeneration with dissolution of microtubules and neurofilaments. Even endothelial cells that appear ultrastructurally intact lose their crucial function of maintenance of the blood- brain barrier. Consequently, introduction of a protective gene(s) to treat experimental allergic encephalomyelitis must be able to protect axons, glial cells, and endothelial cells against structural and functional injuries. The levels of antioxidant enzymes and free radical scavengers in the optic nerve and central nervous system are inadequate to protect these tissues against reactive oxygen species- induced injury in experimental allergic encephalomyelitis and perhaps in other optic neuropathies as well. Therefore, candidate gene(s) for transfer may include reactive oxygen species scavengers such as catalase and superoxide dismutase. Superoxide dismutase dismutes superoxide to hydrogen peroxide (H O₂) and catalase detoxifies the H₂O₂ to H O and O₂. Exogenous administration of catalase scavenged H₂O₂ reduced blood-brain barrier disruption and demyelination in animals with experimental allergic encephalomyelitis (Guy et al, 1986); however, optic neuritis recurred in these animals due to the inability of catalase to cross the blood-brain barrier after integrity was restored by the catalase-mediated detoxification of H₂O . The inventors reasoned that ransfer of genes encoding reactive oxygen species scavengers would increase the cellular defenses against reactive oxygen species in the optic nerve.

4.3 Demyelation

Reactive oxygen species (ROS) are mediators of demyelination and disruption of the blood-brain (Honegger et al, 1989; Guy et al, 1989b) barrier (BBB). Reactive oxygen species include superoxide and nitric oxide, released by infiltrating inflammatory cells, and their metabolites hydrogen peroxide (H₂O₂), peroxynitrite, and hydroxyl radical. The role these ROS play in altering the permeability of the BBB and demyelination has been inferred from the beneficial effect of ROS scavengers on the clinical deficits and histopathologic lesions associated with experimental allergic encephalomyelitis (EAE), a frequently used animal model for multiple sclerosis (MS). Scavengers of ROS include catalase and superoxide dismutase. The latter dismutes superoxide to H₂O , and catalase detoxifies the H O₂ to water and molecular oxygen.

Endogenous levels of these ROS scavengers in the optic nerve and brain are inadequate to protect these central nervous system tissues against ROS-induced injury in EAE. Increasing catalase levels by the exogenous administration of this enzyme has been shown to reduce disruption of the BBB and the demyelination of experimental optic neuritis (Guy et al, 1989b). Catalase, however, is a protein that must be administered by daily injections, even with the conjugation of polyethylene glycol to prolong the half-life of the enzyme, Abuchowski et al, 1977) and the restoration of the BBB integrity induced by catalase restricts further access of subsequent injections of this anti-ROS agent into the nervous system, thereby limiting its effectiveness. Transfer of the gene encoding catalase helps surmount these problems by increasing the cellular defenses against ROS in the optic nerve after only a single injection.

Cellular expression using the adeno-associated viral (AAV) vector takes weeks. This may be too long for the treatment of comparable ROS-mediated injury in patients with acute optic neuritis, in whom the inflammatory response and tissue levels of ROS are likely to be maximal during the initial weeks of visual loss. To evaluate the effects of hastening the cellular expression of catalase, the suppressive effects of catalase gene transfer on EAE were analyzed using an adenovirus that results in high levels of protein expression within days of inoculation of the recombinant virus.

4.4 CATALASE EXPRESSION SUPPRESSES OXIDATIVE INJURY IN ANIMALS WITH EAE

Suppression of oxidative injury by viral-mediated transfer of the human catalase gene was tested in the optic nerves of animals with experimental allergic encephalomyelitis (EAE). EAE is an inflammatory autoimmune disorder of primary central nervous system demyelination that has been frequency used as an animal model for the human disease multiple sclerosis (MS). The optic nerve is a frequent site of involvement common to both EAE and MS. Recombinant adeno-associated virus containing the human gene for catalase was injected over the right optic nerve heads of SJL/J mice that were simultaneously sensitized for EAE. After one month, cell- specific catalase activity, evaluated by quantitation of catalase immunogold, was increased approximately two-fold each in endothelia, oligodendroglia, astrocytes, and axons of the optic nerve. Effects of catalase on the histologic lesions of EAE were measured by computerized analysis of the myelin sheath area (for demyelination), optic disc area (for optic nerve head swelling), extent of the cellular infiltrate, extravasated serum albumin labeled by immunogold (for blood-brain barrier disruption), and in vivo H O₂ reaction product. Relative to control, contralateral optic nerves injected with the recombinant virus without a therapeutic gene, catalase gene inoculation reduced demyelination by 38%, optic nerve head swelling by 29%, cellular infiltration by 34%), disruption of the blood-brain barrier by 64%, and in vivo levels of H O₂ by 61%). Because the efficacy of potential treatments for MS are usually initially tested in the EAE animal model, this study suggests that catalase gene delivery by using viral vectors may be a therapeutic strategy for suppression of MS.

4.5 Adeno-Associated Virus Adeno-associated virus-2 (AAV) is a human parvovirus which can be propagated both as a lytic virus and as a pro virus (Cukor etal, 1984). The viral genome consists of linear single-stranded DNA 4679 bases long (Srivastava et al, 1983), flanked by inverted terminal repeats of 145 bases (Lusby and Berns, 1982). For lytic growth AAV requires co-infection with a helper virus. Either adenovirus (Parks et al, 1967) or herpes simplex (Buller et al, 1981) can supply helper function. Without helper, there is no evidence of AAV-specific replication or gene expression (Carter et al, 1983). When no helper is available, AAV can persist as an integrated provirus (Berns et al, 1982).

Integration apparently involves recombination between AAV termini and host sequences and most of the AAV sequences remain intact in the provirus. The ability of AAV to integrate into host DNA is apparently an inherent strategy for insuring the survival of AAV sequences in the absence of the helper virus. When cells carrying an AAV provirus are subsequently superinfected with a helper, the integrated AAV genome is rescued and a productive lytic cycle occurs (Hoggan, 1965).

AAV sequences cloned into prokaryotic plasmids are infectious (Samulski et al, 1982). For example, when the wild type AAV/pBR322 plasmid, pSM620, is transfected into human cells in the presence of adenovirus, the AAV sequences are rescued from the plasmid and a normal AAV lytic cycle ensues. This renders it possible to modify the AAV sequences in the recombinant plasmid and, then, to grow a viral stock of the mutant by transfecting the plasmid into human cells (Hermonat et al, 1984). AAV contains at least three phenotypically distinct regions (Hermonat et al, 1984). The rep region codes for one or more proteins that are required for DNA replication and for rescue from the recombinant plasmid, while the cap and lip regions appear to code for AAV capsid proteins and mutants within these regions are capable of DNA replication (Hermonat et al, 1984). It has been shown that the AAV termini are required for DNA replication. Laughlin et al. (1983) have described the construction of two E. coli hybrid plasmids, each of which contains the entire DNA genome of AAV, and the transfection of the recombinant DNAs into human cell lines in the presence of helper adenovirus to successfully rescue and replicate the AAV genome (See also Tratschin et al, 1984a; 1984b).

4.6 PHARMACEUTICAL COMPOSITIONS In certain embodiments, the present invention concerns formulation of one or more of the rAAV compositions disclosed herein in pharmaceutically-acceptable solutions for administration to a cell or an animal, either alone, or in combination with one or more other modalities of therapy.

It will also be understood that, if desired, the nucleic acid segment, RNA, DNA or PNA compositions that express a demyelinating-suppressive polypeptide such as SOD or catalase, as disclosed herein may be administered in combination with other agents as well, such as, e.g., proteins or polypeptides or various pharmaceutically-active agents. In fact, there is virtually no limit to other components that may also be included, given that the additional agents do not cause a significant adverse effect upon contact with the target cells or host tissues. The rAAV compositions may thus be delivered along with various other agents as required in the particular instance. Such compositions may be purified from host cells or other biological sources, or alternatively may be chemically synthesized as described herein. Likewise, such compositions may further comprise substituted or derivatized RNA, DNA, or PNA compositions.

Formulation of pharmaceutically-acceptable excipients and carrier solutions is well- known to those of skill in the art, as is the development of suitable dosing and treatment regimens for using the particular compositions described herein in a variety of treatment regimens, including e.g., oral, parenteral, intravenous, intranasal, and intramuscular administration and formulation.

4.6.1 ORAL DELIVERY

In certain applications, the pharmaceutical compositions disclosed herein may be delivered via oral administration to an animal. As such, these compositions may be formulated with an inert diluent or with an assimilable edible carrier, or they may be enclosed in hard- or soft-shell gelatin capsule, or they may be compressed into tablets, or they may be incorporated directly with the food of the diet.

The compositions may include excipients and used in the form of ingestible tablets, buccal tables, troches, capsules, elixirs, suspensions, syrups, wafers, and the like. The tablets, troches, pills, capsules and the like may also contain the following: a binder, as gum tragacanth, acacia, cornstarch, or gelatin; excipients, such as dicalcium phosphate; a disintegrating agent, such as corn starch, potato starch, alginic acid and the like; a lubricant, such as magnesium stearate; and a sweetening agent, such as sucrose, lactose or saccharin may be added or a flavoring agent, such as peppermint, oil of wintergreen, or cherry flavoring. When the dosage unit form is a capsule, it may contain, in addition to materials of the above type, a liquid carrier. Various other materials may be present as coatings or to otherwise modify the physical form of the dosage unit. For instance, tablets, pills, or capsules may be coated with shellac, sugar, or both. A syrup of elixir may contain the active compound sucrose as a sweetening agent methyl and propylparabens as preservatives, a dye and flavoring, such as cherry or orange flavor. Of course, any material used in preparing any dosage unit form should be pharmaceutically pure and substantially non-toxic in the amounts employed. In addition, the active compounds may be incorporated into sustained-release preparation and formulations.

Typically, these formulations may contain at least about 0.1 %> of the active compound or more, although the percentage of the active ingredient(s) may, of course, be varied and may conveniently be between about 1 or 2% and about 60% or 70%> or more of the weight or volume of the total formulation. Naturally, the amount of active compound(s) in each therapeutically useful composition may be prepared is such a way that a suitable dosage will be obtained in any given unit dose of the compound. Factors such as solubility, bioavailability, biological half-life, route of administration, product shelf life, as well as other pharmacological considerations will be contemplated by one skilled in the art of preparing such pharmaceutical formulations, and as such, a variety of dosages and treatment regimens may be desirable.

For oral administration the compositions of the present invention may alternatively be incorporated with one or more excipients in the form of a mouthwash, dentifrice, buccal tablet, oral spray, or sublingual orally-administered formulation. For example, 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 oral solution such as one containing sodium borate, glycerin and potassium bicarbonate, or dispersed in a dentifrice, or added in a therapeutically-effective amount to a composition that may include water, binders, abrasives, flavoring agents, foaming agents, and humectants. Alternatively the compositions may be fashioned into a tablet or solution form that may be placed under the tongue or otherwise dissolved in the mouth. 4.6.2 INJECTABLE DELIVERY

In certain circumstances it will be desirable to deliver the pharmaceutical compositions disclosed herein parenterally, intravenously, intramuscularly, or even intraperitoneally as described in U. S. Patent 5,641,515, specifically incorporated herein by reference in its entirety). Solutions of the active compounds as free base or pharmacologically acceptable salts may be prepared in water suitably mixed with a surfactant, such as hydroxypropylcellulose. Dispersions may also 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 (e.g., glycerol, propylene glycol, and liquid polyethylene glycol, and the like), suitable mixtures thereof, and/or vegetable oils. Proper fluidity may 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 ad 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.

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, a sterile aqueous medium that can be employed will be known to those of skill in the art in light of the present disclosure. For example, one dosage may be dissolved in 1 ml of isotonic NaCl 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, and the general safety and purity standards as required by FDA Office of Biologies standards.

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.

The compositions disclosed herein 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 can also 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.

As used herein, "carrier" includes any and all solvents, dispersion media, vehicles, coatings, diluents, antibacterial and antifungal agents, isotonic and absorption delaying agents, buffers, carrier solutions, suspensions, colloids, 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 can also be incorporated into the compositions. The phrase "pharmaceutically-acceptable" refers to molecular entities and compositions that do not produce an allergic or similar untoward reaction when administered to a human. The preparation of an aqueous composition that contains a protein as an active ingredient is well understood in the art. Typically, such compositions are prepared as injectables, either as liquid solutions or suspensions; solid forms suitable for solution in, or suspension in, liquid prior to injection can also be prepared. The preparation can also be emulsified.

4.6.3 NASAL DELIVERY

In certain embodiments, the pharmaceutical compositions may be delivered by intranasal sprays, inhalation, and/or other aerosol delivery vehicles. Methods for delivering genes, nucleic acids, and peptide compositions directly to the lungs via nasal aerosol sprays has been described e.g., in U. S. Patent 5,756,353, incorporated herein by reference in its entirety. Likewise, the delivery of drugs using intranasal microparticle resins (Takenaga et al, 1998) and lysophosphatidyl-glycerol compounds (U. S. Patent 5,725,871, specifically incorporated herein by reference in its entirety) are also well-known in the pharmaceutical arts. Likewise, transmucosal drug delivery in the form of a polytetrafluoroetheylene support matrix is described in U. S. Patent 5,780,045 (specifically incorporated herein by reference in its entirety).

4.6.4 LIPOSOME-, NANOCAPSULE-, AND MICROPARTICLE-MEDIATED DELΓVΈRY In certain embodiments, the inventors contemplate the use of liposomes, nanocapsules, microparticles, microspheres, lipid particles, vesicles, and the like, for the introduction of the compositions of the present invention into suitable host cells. In particular, the compositions of the present invention may be formulated for delivery either encapsulated in a lipid particle, a liposome, a vesicle, a nanosphere, or a nanoparticle or the like. Such formulations may be preferred for the introduction of pharmaceutically-acceptable formulations of the nucleic acids or the rAAV constructs disclosed herein. The formation and use of liposomes is generally known to those of skill in the art (see for example, Lasic, 1998; which describes the use of liposomes and nanocapsules in the targeted antibiotic therapy for intracellular bacterial infections and diseases). Liposomes have been used successfully with a number of cell types that are normally resistant to transfection by other procedures including T cell suspensions, primary hepatocyte cultures and PC 12 cells (Muller et al, 1990). In addition, liposomes are free of the DNA length constraints that are typical of viral-based delivery systems. Liposomes have been used effectively to introduce genes, drugs, radiotherapeutic agents, enzymes, viruses, transcription factors and allosteric effectors into a variety of cultured cell lines and animals. In addition, several successful clinical trials examining the effectiveness of liposome-mediated drug delivery have been completed (Sculier et al, 1988). Furthermore, several studies suggest that the use of liposomes is not associated with autoimmune responses, toxicity or gonadal localization after systemic delivery (Mori and Fukatsu, 1992).

Liposomes are formed from phospholipids that are dispersed in an aqueous medium and spontaneously form multilamellar concentric bilayer vesicles (also termed multilamellar vesicles (MLVs). MLVs generally have diameters of from 25 nm to 4 μm. Sonication of MLVs results in the formation of small unilamellar vesicles (SUVs) with diameters in the range of 200 to 500 A, containing an aqueous solution in the core.

Liposomes bear resemblance to cellular membranes and are contemplated for use in connection with the present invention as carriers for the peptide compositions. They are widely suitable as both water- and lipid-soluble substances can be entrapped, i.e. in the aqueous spaces and within the bilayer itself, respectively. It is possible that the drug-bearing liposomes may even be employed for site-specific delivery of active agents by selectively modifying the liposomal formulation.

The following information may be utilized in generating liposomal formulations. Phospholipids can form a variety of structures other than liposomes when dispersed in water, depending on the molar ratio of lipid to water. At low ratios the liposome is the preferred structure. The physical characteristics of liposomes depend on pH, ionic strength and the presence of divalent cations. Liposomes can show low permeability to ionic and polar substances, but at elevated temperatures undergo a phase transition that markedly alters their permeability. The phase transition involves a change from a closely packed, ordered structure, known as the gel state, to a loosely packed, less-ordered structure, known as the fluid state. This occurs at a characteristic phase-transition temperature and results in an increase in permeability to ions, sugars and drugs.

In addition to temperature, exposure to proteins can alter the permeability of liposomes. Certain soluble proteins, such as cytochrome c, bind, deform and penetrate the bilayer, thereby causing changes in permeability. Cholesterol inhibits this penetration of proteins, apparently by packing the phospholipids more tightly. It is contemplated that the most useful liposome formations for antibiotic and inhibitor delivery will contain cholesterol.

The ability to trap solutes varies between different types of liposomes. For example, MLVs are moderately efficient at trapping solutes, but SUVs are extremely inefficient. SUVs offer the advantage of homogeneity and reproducibility in size distribution, however, and a compromise between size and trapping efficiency is offered by large unilamellar vesicles (LUVs). These are prepared by ether evaporation and are three to four times more efficient at solute entrapment than MLVs.

In addition to liposome characteristics, an important determinant in entrapping compounds is the physicochemical properties of the compound itself. Polar compounds are trapped in the aqueous spaces and nonpolar compounds bind to the lipid bilayer of the vesicle. Polar compounds are released through permeation or when the bilayer is broken, but nonpolar compounds remain affiliated with the bilayer unless it is disrupted by temperature or exposure to lipoproteins. Both types show maximum efflux rates at the phase transition temperature. Liposomes interact with cells via four different mechanisms: Endocytosis by phagocytic cells of the reticuloendothelial system such as macrophages and neutrophils; adsorption to the cell surface, either by nonspecific weak hydrophobic or electrostatic forces, or by specific interactions with cell-surface components; fusion with the plasma cell membrane by insertion of the lipid bilayer of the liposome into the plasma membrane, with simultaneous release of liposomal contents into the cytoplasm; and by transfer of liposomal lipids to cellular or subcellular membranes, or vice versa, without any association of the liposome contents. It often is difficult to determine which mechanism is operative and more than one may operate at the same time.

The fate and disposition of intravenously injected liposomes depend on their physical properties, such as size, fluidity, and surface charge. They may persist in tissues for h or days, depending on their composition, and half lives in the blood range from min to several h. Larger liposomes, such as MLVs and LUVs, are taken up rapidly by phagocytic cells of the reticuloendothelial system, but physiology of the circulatory system restrains the exit of such large species at most sites. They can exit only in places where large openings or pores exist in the capillary endothelium, such as the sinusoids of the liver or spleen. Thus, these organs are the predominate site of uptake. On the other hand, SUVs show a broader tissue distribution but still are sequestered highly in the liver and spleen. In general, this in vivo behavior limits the potential targeting of liposomes to only those organs and tissues accessible to their large size. These include the blood, liver, spleen, bone marrow, and lymphoid organs.

Targeting is generally not a limitation in terms of the present invention. However, should specific targeting be desired, methods are available for this to be accomplished. Antibodies may be used to bind to the liposome surface and to direct the antibody and its drug contents to specific antigenic receptors located on a particular cell-type surface. Carbohydrate determinants (glycoprotein or glycolipid cell-surface components that play a role in cell-cell recognition, interaction and adhesion) may also be used as recognition sites as they have potential in directing liposomes to particular cell types. Mostly, it is contemplated that intravenous injection of liposomal preparations would be used, but other routes of administration are also conceivable.

Alternatively, the invention provides for pharmaceutically-acceptable nanocapsule formulations of the compositions of the present invention. Nanocapsules can generally entrap compounds in a stable and reproducible way. To avoid side effects due to intracellular polymeric overloading, such ultrafine particles (sized around 0.1 μm) should be designed using polymers able to be degraded in vivo. Biodegradable polyalkyl-cyanoacrylate nanoparticles that meet these requirements are contemplated for use in the present invention.

4.6.5 ADDITIONAL MODES OF DELIVERY

In addition to the methods of delivery described above, the following techniques are also contemplated as alternative methods of delivering the catalase-expressing or SOD-expressing polynucleotide compositions to a target cell or animal. Sonophoresis (i.e., ultrasound) has been used and described in U. S. Patent 5,656,016 (specifically incorporated herein by reference in its entirety) as a device for enhancing the rate and efficacy of drug permeation into and through the circulatory system. Other drug delivery alternatives contemplated are intraosseous injection, microchip devices, ophthalmic formulations, transdermal matrices and feedback controlled delivery.

4.7 THERAPEUTIC AND DIAGNOSTIC KITS

The invention also encompasses one or more compositions together with one or more pharmaceutically-acceptable excipients, carriers, diluents, adjuvants, and/or other components, as may be employed in the formulation of particular rAAV-polynucleotide delivery formulations, and in the preparation of anti-demyelinating agents for administration to an animal. As such, preferred animals for administration of the pharmaceutical compositions disclosed herein include mammals, and particularly humans. Other preferred animals include murines, bovines, equines, porcines, canines, and felines. The composition may include partially or significantly purified compositions, either alone, or in combination with one or more additional active ingredients, which may be obtained from natural or recombinant sources, or which may be obtainable naturally or either chemically synthesized, or alternatively produced in vitro from recombinant host cells expressing DNA segments encoding such additional active ingredients.

Therapeutic kits may also be prepared that comprise at least one of the compositions disclosed herein and instructions for using the composition as a therapeutic agent. The container means for such kits may typically comprise at least one vial, test tube, flask, bottle, syringe or other container means, into which the disclosed rAAV composition(s) may be placed, and preferably suitably aliquoted. Where a second anti-demyelinating agent is also provided, the kit may also contain a second distinct container means into which this second composition may be placed. Alternatively, the plurality of demyelinating compositions may be prepared in a single pharmaceutical composition, and may be packaged in a single container means, such as a vial, flask, syringe, bottle, or other suitable single container means. The kits of the present invention will also typically include a means for containing the vial(s) in close confinement for commercial sale, such as, e.g., injection or blow-molded plastic containers into which the desired vial(s) are retained.

4.8 METHODS OF NUCLEIC ACID DELIVERY AND DNA TRANSFECTION

In certain embodiments, it is contemplated that one or more RNA, DNA, PNAs and/or substituted polynucleotide compositions disclosed herein will be used to transfect an appropriate host cell. Technology for introduction of PNAs, RNAs, and DNAs into cells is well-known to those of skill in the art.

Several non-viral methods for the transfer of expression constructs into cultured mammalian cells also are contemplated by the present invention. These include calcium phosphate precipitation, electroporation, direct microinjection, DNA-loaded liposomes and lipofectamine-DNA complexes, cell sonication, gene bombardment using high velocity microprojectiles, and receptor-mediated transfection. Some of these techniques may be successfully adapted for in vivo or ex vivo use. Moreover, the use of viral vectors including retroviruses, baculoviruses, adenoviruses, adenoassociated viruses, vaccinia viruses, Herpes viruses, and the like are well-known in the art, and are described in detail herein.

4.9 EXPRESSION IN ANIMAL CELLS

The inventors contemplate that a polynucleotide comprising a contiguous nucleic acid sequence that encodes a catalase or a SOD enzyme may be utilized to treat demyelinating disorders in a transformed host cell. Such cells are preferably animal cells, including mammalian cells such as those obtained from a human or other primate, murine, canine, bovine, equine, epine, or porcine species. The cells may be transformed with one or more rAAV vectors comprising an SOD- or catalase-encoding construct of interest, such that the construct is sufficient to alter, reduce, ameliorate or prevent the effects of demyelination in vitro and/or in vivo.

4.10 CHARACTERIZATION

To confirm the presence of the exogenous DNA or "transgene(s)" in the transformed cells, a variety of assays may be performed. Such assays include, for example, "molecular biological" assays, such as Southern and Northern blotting, RT-PCR™ and PCR™;

"biochemical" assays, such as detecting the presence of a protein product, e.g., by immunological means (ELISAs and Western blots) or by enzymatic function assay.

4.11 GENE EXPRESSION

While Southern blotting and PCR™ may be used to detect the transgene(s) in question, they do not provide information as to whether the gene is being expressed. Expression may be evaluated by RT-PCR™ for mRNA and/or specifically identifying the protein products of the introduced genes or evaluating the phenotypic changes brought about by their expression.

Assays for the production and identification of specific proteins may make use of physical-chemical, structural, functional, or other properties of the proteins. Unique physical- chemical or structural properties allow the proteins to be separated and identified by electrophoretic procedures, such as native or denaturing gel electrophoresis or isoelectric focusing, or by chromatographic techniques such as ion exchange or gel exclusion chromatography. The unique structures of individual proteins offer opportunities for use of specific antibodies to detect their presence in formats such as an ELISA assay. Combinations of approaches may be employed with even greater specificity such as western blotting in which antibodies are used to locate individual gene products that have been separated by electrophoretic techniques. Additional techniques may be employed to absolutely confirm the identity of the product of interest such as evaluation by arnino acid sequencing following purification. Although these are among the most commonly employed, other procedures may be additionally used.

Assay procedures may also be used to identify the expression of proteins by their functionality, especially the ability of enzymes to catalyze specific chemical reactions involving specific substrates and products. These reactions may be followed by providing and quantifying the loss of substrates or the generation of products of the reactions by physical or chemical procedures. Examples are as varied as the enzyme to be analyzed and may include assays for PAT enzymatic activity by following production of radiolabeled acetylated phosphinothricin from phosphinothricin and ¹⁴C-acetyl CoA or for anthranilate synthase activity by following loss of fluorescence of anthranilate, to name two. Very frequently the expression of a gene product is determined by evaluating the phenotypic results of its expression. These assays also may take many forms including but not limited to analyzing changes in the chemical composition, morphology, or physiological properties of the cells of the animal or human.

4.12 DNA INTEGRATION, RNA EXPRESSION AND INHERITANCE

Genomic DNA may be isolated from animal cell lines or any animal parts to determine the presence of the exogenous gene through the use of techniques well known to those skilled in the art. Note that intact sequences will not always be present, presumably due to rearrangement or deletion of sequences in the cell. The presence of DNA elements introduced through the methods of this invention may be determined by polymerase chain reaction (PCR™). Using this technique, discreet fragments of DNA are amplified and detected by gel electrophoresis. This type of analysis permits one to determine whether a gene is present in a stable transformant, but does not prove integration of the introduced gene into the host cell genome. It is the experience of the inventors, however, that DNA has been integrated into the genome of all transformants that demonstrate the presence of the gene through PCR™ analysis. In addition, it is not possible using PCR™ techniques to determine whether transformants have exogenous genes introduced into different sites in the genome, i.e., whether transformants are of independent origin. It is contemplated that using PCR™ techniques it would be possible to clone fragments of the host genomic DNA adjacent to an introduced gene.

Positive proof of DNA integration into the host genome and the independent identities of transformants may be determined using the technique of Southern hybridization. Using this technique, specific DNA sequences that were introduced into the host genome and flanking host DNA sequences can be identified. Hence the Southern hybridization pattern of a given transformant serves as an identifying characteristic of that transformant. In addition it is possible through Southern hybridization to demonstrate the presence of introduced genes in high molecular weight DNA, i.e., confirm that the introduced gene has been integrated into the host cell genome. The technique of Southern hybridization provides information that is obtained using PCR™ e.g., the presence of a gene, but also demonstrates integration into the genome and characterizes each individual transformant.

It is contemplated that using the techniques of dot or slot blot hybridization which are modifications of Southern hybridization techniques one could obtain the same information that is derived from PCR™, e.g., the presence of a gene.

Whereas DNA analysis techniques may be conducted using DNA isolated from any part of an animal, RNA will only be expressed in particular cells or tissue types and hence it will be necessary to prepare RNA for analysis from these tissues. PCR™ techniques may also be used for detection and quantitation of RNA produced from introduced genes. In this application of PCR™ it is first necessary to reverse transcribe RNA into DNA, using enzymes such as reverse transcriptase, and then through the use of conventional PCR™ techniques amplify the DNA. In most instances PCR™ techniques, while useful, will not demonstrate integrity of the RNA product. Further information about the nature of the RNA product may be obtained by Northern blotting. This technique will demonstrate the presence of an RNA species and give information about the integrity of that RNA. The presence or absence of an RNA species can also be determined using dot or slot blot Northern hybridization. These techniques are modifications of Northern blotting and will only demonstrate the presence or absence of an RNA species.

4.13 SELECTABLE MARKERS

In certain embodiments of the invention, the delivery of a nucleic acid in a cell, and in particular, an rAAV construct that expresses a SOD or a catalase may be identified in vitro or in vivo by including a marker in the expression construct. The marker would result in an identifiable change to the transfected cell permitting ready identification of expression. Usually the inclusion of a drug selection marker aids in cloning and in the selection of transformants, for example, neomycin, puromycin, hygromycin, DHFR, GPT, zeocin and histidinol. Alternatively, enzymes such as herpes simplex virus thymidine kinase (tk) (eukaryotic) or chloramphenicol acetyltransferase (CAT) (prokaryotic) may be employed, as well as markers such as green fluorescent protein, luciferase, and the like. Immunologic markers also can be employed. The selectable marker employed is not believed to be important, as 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.

The enzyme luciferase is useful as a screenable marker in the context of the present invention. In the presence of the substrate luciferin, cells expressing luciferase emit light which can be detected on photographic or x-ray film, in a luminometer (or liquid scintillation counter), by devices that enhance night vision, or by a highly light sensitive video camera, such as a photon counting camera. These assays are nondestructive so that transformed cells may be cultured further following identification. A photon counting camera is especially useful as it allows one to identify specific cells or groups of cells that are expressing luciferase and manipulate those in real time. Green fluorescent protein (gφ) is also useful as a screenable marker.

4.14 SITE-SPECIFIC MUTAGENESIS

Site-specific mutagenesis is a technique useful in the preparation of individual peptides, or biologically functional equivalent polypeptides, through specific mutagenesis of the underlying polynucleotides that encode them. The technique, well-known to those of skill in the art, further provides a ready ability to prepare and test sequence variants, for example, incorporating one or more of the foregoing considerations, by introducing one or more nucleotide sequence changes into the DNA. Site-specific mutagenesis allows the production of mutants through the use of specific oligonucleotide sequences which encode the DNA sequence of the desired mutation, as well as a sufficient number of adjacent nucleotides, to provide a primer sequence of sufficient size and sequence complexity to form a stable duplex on both sides of the deletion junction being traversed. Mutations may be employed in a selected polynucleotide sequence to improve, alter, decrease, modify, or change the properties of the polynucleotide itself, and/or alter the properties, activity, composition, stability, or primary sequence of the encoded polypeptide.

In certain embodiments of the present invention, the inventors contemplate the mutagenesis of the contemplated SOD- and/or catalase-encoding polynucleotide sequences to alter the activity or effectiveness of such constructs in inhibiting or altering the demyelinating activity in a transformed host cell. Likewise in certain embodiments, the inventors contemplate the mutagenesis of such genes themselves, or of the rAAV delivery vehicle to facilitate improved regulation of the enzyme's activity in vitro and/or in vivo.

The techniques of site-specific mutagenesis are well-known in the art, and are widely used to create variants of both polypeptides and polynucleotides. For example, site-specific mutagenesis is often used to alter a specific portion of a DNA molecule. In such embodiments, a primer comprising typically about 14 to about 25 nucleotides or so in length is employed, with about 5 to about 10 residues on both sides of the junction of the sequence being altered.

As will be appreciated by those of skill in the art, site-specific mutagenesis techniques have often employed a phage vector that exists in both a single stranded and double stranded form. Typical vectors useful in site-directed mutagenesis include vectors such as the Ml 3 phage. These phage are readily commercially-available and their use is generally well-known to those skilled in the art. Double-stranded plasmids are also routinely employed in site directed mutagenesis that eliminates the step of transferring the gene of interest from a plasmid to a phage.

In general, site-directed mutagenesis in accordance herewith is performed by first obtaining a single-stranded vector or melting apart of two strands of a double-stranded vector that includes within its sequence a DNA sequence that encodes the desired peptide. An oligonucleotide primer bearing the desired mutated sequence is prepared, generally synthetically. This primer is then annealed with the single-stranded vector, and subjected to DNA polymerizing enzymes such as E. coli polymerase I Klenow fragment, in order to complete the synthesis of the mutation-bearing strand. Thus, a heteroduplex is formed wherein one strand encodes the original non-mutated sequence and the second strand bears the desired mutation. This heteroduplex vector is then used to transform appropriate cells, such as E. coli cells, and clones are selected which include recombinant vectors bearing the mutated sequence arrangement.

The preparation of sequence variants of the selected peptide-encoding DNA segments using site-directed mutagenesis provides a means of producing potentially useful species and is not meant to be limiting as there are other ways in which sequence variants of peptides and the DNA sequences encoding them may be obtained. For example, recombinant vectors encoding the desired peptide sequence may be treated with mutagenic agents, such as hydroxylamine, to obtain sequence variants. Specific details regarding these methods and protocols are found in the teachings of Maniatis et al. , 1982.

As used herein, the term "oligonucleotide directed mutagenesis procedure" refers to template-dependent processes and vector-mediated propagation which result in an increase in the concentration of a specific nucleic acid molecule relative to its initial concentration, or in an increase in the concentration of a detectable signal, such as amplification. As used herein, the term "oligonucleotide directed mutagenesis procedure" is intended to refer to a process that involves the template-dependent extension of a primer molecule. The term template dependent process refers to nucleic acid synthesis of an RNA or a DNA molecule wherein the sequence of the newly synthesized strand of nucleic acid is dictated by the well-known rules of complementary base pairing. Typically, vector mediated methodologies involve the introduction of the nucleic acid fragment into a DNA or RNA vector, the clonal amplification of the vector, and the recovery of the amplified nucleic acid fragment.

A number of template dependent processes are available to amplify the target sequences of interest present in a sample. One of the best known amplification methods is the polymerase chain reaction (PCR™). Briefly, in PCR™, two primer sequences are prepared which are complementary to regions on opposite complementary strands of the target sequence. An excess of deoxynucleoside triphosphates is added to a reaction mixture along with a DNA polymerase (e.g., Taq polymerase). If the target sequence is present in a sample, the primers will bind to the target and the polymerase will cause the primers to be extended along the target sequence by adding on nucleotides. By raising and lowering the temperature of the reaction mixture, the extended primers will dissociate from the target to form reaction products, excess primers will bind to the target and to the reaction product and the process is repeated. Preferably reverse transcription and PCR™ amplification procedure may be performed in order to quantify the amount of mRNA amplified. Polymerase chain reaction methodologies are well known in the art. Another method for amplification is the ligase chain reaction (referred to as LCR), In

LCR, two complementary probe pairs are prepared, and in the presence of the target sequence, each pair will bind to opposite complementary strands of the target such that they abut. In the presence of a ligase, the two probe pairs will link to form a single unit. By temperature cycling, as in PCR™, bound ligated units dissociate from the target and then serve as "target sequences" for ligation of excess probe pairs. U. S. Patent No. 4,883,750, incorporated herein by reference in its entirety, describes an alternative method of amplification similar to LCR for binding probe pairs to a target sequence.

Qbeta Replicase, may also be used as still another amplification method in the present invention. In this method, a replicative sequence of RNA that has a region complementary to that of a target is added to a sample in the presence of an RNA polymerase. The polymerase will copy the replicative sequence that can then be detected. An isothermal amplification method, in which restriction endonucleases and ligases are used to achieve the amplification of target molecules that contain nucleotide 5'-[α-thio]triphosphates in one strand of a restriction site (Walker et al, 1992), may also be useful in the amplification of nucleic acids in the present invention.

Strand Displacement Amplification (SDA) is another method of carrying out isothermal amplification of nucleic acids which involves multiple rounds of strand displacement and synthesis, i.e. nick translation. A similar method, called Repair Chain Reaction (RCR) is another method of amplification which may be useful in the present invention and is involves annealing several probes throughout a region targeted for amplification, followed by a repair reaction in which only two of the four bases are present. The other two bases can be added as biotinylated derivatives for easy detection. A similar approach is used in SDA.

Sequences can also be detected using a cyclic probe reaction (CPR). In CPR, a probe having a 3' and 5' sequences of non-target DNA and an internal or "middle" sequence of the target protein specific RNA is hybridized to DNA which is present in a sample. Upon hybridization, the reaction is treated with RNaseH, and the products of the probe are identified as distinctive products by generating a signal that is released after digestion. The original template is annealed to another cycling probe and the reaction is repeated. Thus, CPR involves amplifying a signal generated by hybridization of a probe to a target gene specific expressed nucleic acid.

Still other amplification methods may be used in accordance with the present invention. In the former application, "modified" primers are used in a PCR-like, template and enzyme dependent synthesis. The primers may be modified by labeling with a capture moiety (e.g., biotin) and/or a detector moiety (e.g., enzyme). In the latter application, an excess of labeled probes is added to a sample. In the presence of the target sequence, the probe binds and is cleaved catalytically. After cleavage, the target sequence is released intact to be bound by excess probe. Cleavage of the labeled probe signals the presence of the target sequence.

Other nucleic acid amplification procedures include transcription-based amplification systems (TAS), including nucleic acid sequence based amplification (NASBA) and 3SR. In NASBA, the nucleic acids can be prepared for amplification by standard phenol/chloroform extraction, heat denaturation of a sample, treatment with lysis buffer and minispin columns for isolation of DNA and RNA or guanidinium chloride extraction of RNA. These amplification techniques involve annealing a primer that has sequences specific to the target sequence. Following polymerization, DNA/RNA hybrids are digested with RNase H while double stranded DNA molecules are heat-denatured again. In either case the single stranded DNA is made fully double stranded by addition of second target-specific primer, followed by polymerization. The double stranded DNA molecules are then multiply transcribed by a polymerase such as T7 or SP6. In an isothermal cyclic reaction, the RNAs are reverse transcribed into DNA, and transcribed once again with a polymerase such as T7 or SP6. The resulting products, whether truncated or complete, indicate target-specific sequences.

Another nucleic acid amplification process involves cyclically synthesizing single-stranded RNA ("ssRNA"), ssDNA, and double-stranded DNA (dsDNA), which may be used in accordance with the present invention. The ssRNA is a first template for a first primer oligonucleotide, which is elongated by reverse transcriptase (RNA-dependent DNA polymerase). The RNA is then removed from resulting DNA:RNA duplex by the action of ribonuclease H (RNase H, an RNase specific for RNA in a duplex with either DNA or RNA). The resultant ssDNA is a second template for a second primer, which also includes the sequences of an RNA polymerase promoter (exemplified by T7 RNA polymerase) 5' to its homology to its template. This primer is then extended by DNA polymerase (exemplified by the large "Klenow" fragment of E. coli DNA polymerase I), resulting as a double-stranded DNA ("dsDNA") molecule, having a sequence identical to that of the original RNA between the primers and having additionally, at one end, a promoter sequence. This promoter sequence can be used by the appropriate RNA polymerase to make many RNA copies of the DNA. These copies can then re-enter the cycle leading to very swift amplification. With proper choice of enzymes, this amplification can be done isothermally without addition of enzymes at each cycle. Because of the cyclical nature of this process, the starting sequence can be chosen to be in the form of either DNA or RNA.

11 - A nucleic acid sequence amplification scheme may be used based on the hybridization of a promoter/primer sequence to a target single-stranded DNA ("ssDNA") followed by transcription of many RNA copies of the sequence. This scheme is not cyclic; i.e. new templates are not produced from the resultant RNA transcripts. Other amplification methods include "RACE" and "one-sided PCR" which are well-known to those of skill in the art.

Methods based on ligation of two (or more) oligonucleotides in the presence of nucleic acid having the sequence of the resulting "di-oligonucleotide", thereby amplifying the di-oligonucleotide (Wu and Dean, 1996), may also be used in the amplification of DNA sequences of the present invention.

4.15 BIOLOGICAL FUNCTIONAL EQUIVALENTS

Modification and changes may be made in the structure of the polynucleotides and polypeptides of the present invention and still obtain a functional molecule that encodes a polypeptide with desirable characteristics. As mentioned above, it is often desirable to introduce one or more mutations into a specific polynucleotide sequence. In certain circumstances, the resulting encoded polypeptide sequence is altered by this mutation, or in other cases, the sequence of the polypeptide is unchanged by one or more mutations in the encoding polynucleotide.

When it is desirable to alter the amino acid sequence of a polypeptide to create an equivalent, or even an improved, second-generation molecule, the amino acid changes may be achieved by changing one or more of the codons of the encoding DNA sequence, according to Table 1.

For example, certain amino acids may be substituted for other amino acids in a protein structure without appreciable loss of interactive binding capacity with structures such as, for example, antigen-binding regions of antibodies or binding sites on substrate molecules. Since it is the interactive capacity and nature of a protein that defines that protein's biological functional activity, certain amino acid sequence substitutions can be made in a protein sequence, and, of course, its underlying DNA coding sequence, and nevertheless obtain a protein with like properties. It is thus contemplated by the inventors that various changes may be made in the peptide sequences of the disclosed compositions, or corresponding DNA sequences which encode said peptides without appreciable loss of their biological utility or activity.

52 - TABLE 1

Amino Acids Codons

Alanine Ala A GCA GCC GCG GCU

Cysteine Cys C UGC UGU

Aspartic acid Asp D GAC GAU

Glutamic acid Glu E GAA GAG

Phenylalanine Phe F UUC UUU

Glycine Gly G GGA GGC GGG GGU

Histidine His H CAC CAU

Isoleucine He I AUA AUC AUU

Lysine Lys K AAA AAG

Leucine Leu L UUA UUG CUA CUC CUG CUU

Methionine Met M AUG

Asparagine Asn N AAC AAU

Proline Pro P CCA CCC CCG CCU

Glutamine Gin Q CAA CAG

Arginine Arg R AGA AGG CGA CGC CGG CGU

Serine Ser S AGC AGU UCA UCC UCG UCU

Threonine Thr T ACA ACC ACG ACU

Valine Val V GUA GUC GUG GUU

Tryptophan Tip w UGG

Tyrosine Tyr Y UAC UAU

In making such changes, the hydropathic index of amino acids may be considered. The importance of the hydropathic amino acid index in conferring interactive biologic function on a protein is generally understood in the art (Kyte and Doolittle, 1982, incorporate herein by reference). It is accepted that the relative hydropathic character of the amino acid contributes to the secondary structure of the resultant protein, which in turn defines the interaction of the protein with other molecules, for example, enzymes, substrates, receptors, DNA, antibodies, antigens, and the like. Each amino acid has been assigned a hydropathic index on the basis of its hydrophobicity and charge characteristics (Kyte and Doolittle, 1982). These values are: isoleucine (+4.5); valine (+4.2); leucine (+3.8); phenylalanine (+2.8); cysteine/cystine (+2.5); methionine (+1.9); alanine (+1.8); glycine (-0.4); threonine (-0.7); serine (-0.8); tryptophan (- 0.9); tyrosine (-1.3); proline (-1.6); histidine (-3.2); glutamate (-3.5); glutamine (-3.5); aspartate (-3.5); asparagine (-3.5); lysine (-3.9); and arginine (-4.5).

It is known in the art that certain amino acids may be substituted by other amino acids having a similar hydropathic index or score and still result in a protein with similar biological activity, i.e. still obtain a biological functionally equivalent protein. In making such changes, the substitution of amino acids whose hydropathic indices are within ±2 is preferred, those within +1 are particularly preferred, and those within ±0.5 are even more particularly preferred. It is also understood in the art that the substitution of like amino acids can be made effectively on the basis of hydrophihcity. U. S. Patent 4,554,101 (specifically incorporated herein by reference in its entirety), states that the greatest local average hydrophihcity of a protein, as governed by the hydrophihcity of its adjacent amino acids, correlates with a biological property of the protein.

As detailed in U. S. Patent 4,554,101, the following hydrophihcity values have been assigned to amino acid residues: arginine (+3.0); lysine (+3.0); aspartate (+3.0 ± 1); glutamate (+3.0 ± 1); serine (+0.3); asparagine (+0.2); glutamine (+0.2); glycine (0); threonine (-0.4); proline (-0.5 ± 1); alanine (-0.5); histidine (-0.5); cysteine (-1.0); methionine (-1.3); valine (- 1.5); leucine (-1.8); isoleucine (-1.8); tyrosine (-2.3); phenylalanine (-2.5); tryptophan (-3.4). It is understood that an amino acid can be substituted for another having a similar hydrophihcity value and still obtain a biologically equivalent, and in particular, an immunologically equivalent protein. In such changes, the substitution of amino acids whose hydrophihcity values are within ±2 is preferred, those within ±1 are particularly preferred, and those within ±0.5 are even more particularly preferred.

As outlined above, amino acid substitutions are generally therefore based on the relative similarity of the amino acid side-chain substituents, for example, their hydrophobicity, hydrophihcity, charge, size, and the like. Exemplary substitutions that take various of the foregoing characteristics into consideration are well known to those of skill in the art and include: arginine and lysine; glutamate and aspartate; serine and threonine; glutamine and asparagine; and valine, leucine and isoleucine.

5.0 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 represent techniques discovered by the inventors 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 spirit and scope of the invention.

5.1 EXAMPLE 1-LONG TERM EXPRESSION IN OPTIC NERVE

This example illustrates that viral mediated gene transfer can be successfully accomplished in the optic nerve. In this study the duration of foreign gene expression in glial cells, blood vessels, and axons of the optic nerve with a single injection of recombinant adeno- associated virus (rAAV) was investigated in strain- 13 guinea pigs that are susceptible to induction of experimental allergic encephalomyelitis.

5.1.1 Promoter and Gene Construction

The immediate early cytomegalovirus (CMV) promoter was linked to (1) a lacZ-SV40 polyA reporter gene or (2) the reporter Aquoria victoria green fluorescent protein (gφ) complementary DNA (cDNA) using standard protocols. The final constructs contained either the Escherichia coli -galactosidase gene or a synthetic humanized (hgφ) gene. Each reporter was driven by the CMV immediate early promoter flanked at both sides by wild-type AAV terminal repeats.

5.1.2 rAAV Construction

Plasmids pTRCMV-lacZ or pTRCMV-hgφ were packaged into rAAV by transfection into 293 cells (human embryonic kidney cells) that were coinfected with a replication-defective AAV packaging plasmid (pIM45) containing the wild-type AAV genome without the terminal repeats. Cultures were then coinfected with a temperature-sensitive helper virus — adenovirus tsl49 for lacZ or wild-type adenovirus for hgfp at a multiplicity of infection of 10. After 60 hours of incubation, rAAV was harvested by freeze-thawing 3 times.

Contaminating helper adenovirus was heat inactivated for 30 minutes at 56°C. The cellular debris was centrifuged and rAAV was purified through a cesium chloride gradient formed in an SW41 rotor for 48 hours at 200,000g. The gradient was then fractionated and the density was determined by refractometry. Fractions with densities of between 1.38 and 1.4 g/cm³ were pooled and dialyzed against Dulbecco modified Eagle medium for 4 hours. The

55 - resultant rAAV-packaged test viruses pTRCMV-facZ and pTRCMV-hgjp were then titered for rAAV by an infectious center assay giving titers of 1 x 10^s and 2 x 10⁸ infectious units per milliliter, respectively. They were also tested for contaminating adenovirus by plaque assay for pTRCMV-hgφ and by serial dilution cytopathic effect for pTRCMV-lacZ. Both potentially contaminating viruses were found to be below detection limits; i.e., less than 5 orders of magnitude lower than rAAV.

5.1.3 Injection of rAAV Promoter and Gene Constructs

Strain- 13 guinea pigs were sedated with 0.2 mL of a 1:1 mixture of ketamine hydrochloride (100 mg/mL) and xylazine (20 mg/mL) by intramuscular injection. The pupils were dilated with 2.5% phenylephrine and 0.5% tropicamide followed by a topical anesthetic (proparacaine hydrochloride) administered to the cornea. Paracentesis of the anterior chamber with a 25-gauge needle was done to lower the intraocular pressure. A 30-gauge needle attached to a syringe was inserted through the pars plana and positioned over the optic nerve head under visualization with a 28-diopter lens and the indirect ophthalmoscope, then approximately 2 x 10⁶to 4 x 10⁶ infectious particles of the viral-encapsulated cDNA gene constructs of (1) pTRCMV-lacZ (19 animals), (2) pTRCMV-hgφ (5 animals), or (3) AAV without the promoter and reporter elements (2 animals) were injected into the vitreous of 1 eye of each animal.

5.1.4 Fundus Photography

To test for potential ocular disease due to the viral injections or for ocular infections, we performed in vivo fundus photographs of the retina and optic nerve head of guinea pig eyes with a Zeiss fundus camera. Prior to photography, the pupils were dilated with 2.5% phenylephrine and 0.5%) tropicamide. For in vivo visualization of hgφ-induced fluorescence (emission maximum at 509 nM), additional fundus photographs were taken with a blue excitation light and a barrier filter. The contralateral eye was also photographed to serve as a negative control for fluorescence. All fundus photographs were repeated at weekly intervals for 1 month following the intravitreal injections.

5.1.5 Histochemistry

For evaluation of transgene expression, the animals were overdosed with pentobarbital as follows: (1) at 1 week (n=l), 2 weeks (n=8), 4 weeks (n= ), 5 weeks (n=l), 3 months (n=2), 6 months (n=l), and 1 year (n=5) for the reporter gene lacZ; (2) at 4 weeks for the reporter gene hgφ (n=5); or (3) at 2 weeks for the AAV without the promoter and reporter elements (n=2). The eyes of 4 animals that received no viral injections were also used. After deep surgical anesthesia was obtained with the pentobarbital overdose, the chest cavity was opened and the animals were perfused by intracardiac injection with 4%> paraformaldehyde and 0.1-mol L phosphate-buffered saline (PBS). The globes and optic nerves were immediately dissected out, then the cornea, lens, and vitreous of each eye were removed by incision at the ora serrata. The posterior eyecups were immersion fixed in 4% paraformaldehyde and 0.1-mol/L PBS for 15 minutes and washed in 0.1-mol/L PBS (pH 7.4). The eye cups were incubated in 5-bromo-4-chloro-3-indolyl~D-galactoside (β-Gal) (1 mg/mL) plus 5-mmol/L potassium ferricyanide, 5-mmol/L potassium ferrocyanide, and 2- mmol/L magnesium chloride in a gently shaking water bath at 35°C overnight. The reaction was terminated by washes in 0.1-mol/L PBS, then the eye cups were cryoprotected in a graded series of 7.5%, 15%, and 30% sucrose buffers in 0.1-mol/L PBS (pH 7.4). The optic nerves were trephined from the eye cups, then the specimens were embedded in OCT medium and snap frozen in liquid nitrogen or embedded in LR-white resin (London Resin Co, Ltd, Basingstoke, Hampshire, England) after dehydration in a graded series of ethanol buffers. Cryosections 10-μm to 30-μm thick were mounted on gelatin-subbed glass slides for immunostaining and "silanized" glass slides for in situ reverse transcription-polymerase chain reaction (RT-PCR). Semithin (0.5 μm) and ultrathin (90 nm) LR- white-embedded sections of the optic nerves of the 6-month and 1-year postinjection animals were processed for immunostaining for lacZ at the light and ultrastructural levels.

Photographs of specimens were made with bright-field and differential interference contrast optics with a microscope (Axiophot; Carl Zeiss, Inc, Thomwood, NY). Ultrastructural examination of selected tissue was made with a transmission electron microscope (model H 7000; Hitachi, Inc, Tokyo, Japan). Hgφ fluorescent images were collected on a scanning laser confocal microscope (BioRad Lab, Inc, Herculles, CA). The BioRad Al-A cubes were used with argon laser excitation at 514 nm and emission collected at 520 to 560 nm.

5.1.6 Immunohistochemistry

After quenching of endogenous peroxidase activity by incubation in 0.5%) H₂O for 30 minutes, specimens that had been reacted with β-gal were washed in 0.1-mol/L PBS, then incubated in 5%> normal goat serum for 30 minutes. Sections were incubated in rabbit polyclonal (1) anti-glial fibrillary acidic protein (GFAP) (Sigma- Aldrich Corporation, St Louis, Mo) to label astrocytes, (2) anti-carbonic anhydrase (CA) II (Sigma-Aldrich) to label oligodendroglial cells,or (3) anti-lacZ (5-Prime~>3-Prime; Prime, Inc, Boulder, Colo) overnight at 4°C. After washings, sections were incubated in goat anti-rabbit IgG peroxidase (for GFAP and CA II) or goat anti- rabbit IgG conjugated to alkaline phosphatase (for lacZ) overnight at 4°C.

Sections were washed, developed in diaminobenzidine (DAB)-H₂O₂ substrate (for immunoperoxidase) or 5-bromo-4-chloro-3-indolyl phosphate and nitroblue tetrazolium substrates (for alkaline phosphatase), and then washed in tap water. The above protocols were also used on control specimens with the exception that the primary antibody was omitted.

For ultrastructual analysis of lacZ-transduced cells, ultrathin sections were placed on nickel grids, then washed in deionized water. Grids were floated on 0.01-mol/L PBS, 0.1-mol/L sodium chloride, and 5% bovine serum albumin (pH 7.2), and then reacted with rabbit anti-lacZ antibody in the same buffer for 2 hours at room temperature. After washes in 0.01-mol/L Tris- hydrochioride-buffered saline, the grids were reacted with 5-nm gold-labeled goat anti-rabbit IgG antibodies diluted with Tris-hydrochloride— buffered saline for 1 hour at room temperature. After washes in Tris-hydrochloride-buffered saline, grids were washed in deionized water, then silver enhanced for 2 minutes with a kit according to the manufacturer's specifications (Goldmark, Pittsburgh, PA). To detect nonspecific binding, the above protocol was also used on control specimens with the exception that the primary antibody was omitted. To ensure the specificity of the antibody labeling, additional control experiments were done by first incubating the specimens with the -galactosidase antibody that was preabsorbed with purified -galactosidase protein (Biogenesis Inc, Sundown, NH).

5.1.7 Rt-PCR Analysis

Cryostat sections (stored at -70°C) of the eye cups and optic nerves that had previously been reacted with β-gal, as described above, were washed in 0.1-mol/L PBS. Endogenous peroxidase activity was quenched by incubation in 0.5%) H O₂ for 30 minutes. For detection of lacZ mRNA, the specimens were digested in 100 μL of proteinase K (10 μg/mL) (Sigma- Aldrich) at 37°C for 15 minutes. Heating cycles were performed in a thermal cycler (PTC- 100- 12MS; MJ Research, Woburn, Mass). To prevent evaporation during heating in the thermal cycler, the slides were covered with a 22-mm piece of parafilm. The digestion was stopped by immersing the slides containing the tissue sections in 0.1-mol/L glycine-PBS buffer for 5 minutes, then washed in PBS for 15 minutes.

For reverse transcription (RT), the slides were incubated in 70 μL of the oligo(dT) mixture (65-μL deionized water + 5-μL oligo[dT]) at 70°C for 10 minutes, then they were incubated in 30 μL of the RT reaction mixture (10 RT buffer [10 μL] + 10-mmol/L deoxyribonucleoside triphosphates [dNTPs] [5 μL] + 0.1-mol/L dithiothreitol [10 μL] + reverse transcriptase [5 μL]) at 20°C for 10 minutes, then at 42°C for 50 minutes. The RT was inactivated by heating to 70°C for 15 minutes and the slides were cooled to 20°C for 10 minutes. All reagents for RT were contained in the Superscript Preamplification System (Life Technologies, Gaithersburg, MD). For PCR, the slides were incubated in 70 μL of the PCR reaction mixture consisting of 10 PCR buffer (10 μL), 1.0-mmol/L of each of the 4 dNTPs (deoxyadenosine triphosphate, deoxycytidine triphosphate, deoxyguanosine triphosphate, deoxythymidine triphosphate) (8 μL), 10-μmol/L digoxigenin-deoxyuridine triphosphate (Boehringer Mannheim, Indianapolis, Ind) (1 μL), 1-mmol/L forward primer 5'-CTG GCG GTA ATA GCG AAG AGG-3' (SEQ ID NO:l) at nucleotide position 105 (1 μL), 1-mmol/L reverse primer 5'GGT GTA GAT GGG CGC ATC3' at nucleotide position 303 (1 μL), 25-mmol/L magnesium chloride (10 μL), Taq DNA polymerase (0.5 μL), TaqStart antibody (Clontech, Palo Alto, Calif) (0.5 μL), and dH₂O (68 μL).

A glass coverslip was placed over the slide-PCR mixture and the edges were glued with rubber cement until dry. Then the slides were cycled at 94°C for 15 seconds, 60°C for 15 seconds, 72°C for 60 seconds, for 20 cycles. Reagents for PCR were obtained from the GeneAmp PCR Core Kit (Perkin-Elmer, Norwalk, Conn). After completion of PCR, the coverslips were removed and the slides were washed in 0.1 standard saline citrate at 45°C for 20 minutes, followed by a wash in 0.1%) bovine serum albumin at 20°C for 15 minutes. For immunodetection of digoxigenin-deoxyuridine triphosphate, an unconjugated monoclonal anti-digoxigenin antibody raised in the mouse (Boehringer Mannheim) was diluted 1/500. The diluted antibody (100 μL) was applied to the slides that were then incubated overnight at 0°C. After incubation, the slides were washed in PBS, then a rabbit anti-mouse antibody conjugated to horseradish peroxidase (100 μL) (Sigma- Aldrich) was applied to the slides that were incubated overnight at 0°C. After incubation, the slides were washed in 0.1- mol/L PBS, then the horseradish peroxidase was developed in DAB-H₂O substrate (100 μL) for 10 to 20 minutes. The slides were then washed in tap water. Two controls were included that (1) omitted the RT step to detect nonspecific binding to nuclear or mitochondrial DNA and (2) omitted the primers in the PCR mix to detect nonspecific staining that was unrelated to cDNA amplification.

5.1.8 Results

Weekly fundus photography, done for 1 month, documented the absence of any ocular abnormality due to the viral injections. No inflammatory response or toxic reaction was detected in the cornea, anterior chamber, crystalline lens, vitreous body, or retina. However, no in vivo hgφ-induced fluorescence of the retina was visualized. All eyes injected with the CMV-lacZ constructs exhibited transduction of cells of the optic nerve at each of the postinjection time points. The optic nerve head and adjacent retrobulbar nerve were the tissues that were most heavily stained by the β-Gal. Two weeks after the CMV-lacZ injection, intense blue β-Gal staining of the optic nerve head was evident in the eye cups processed for -galactosidase expression. β-Galactosidase tissue staining was absent in eye cups from control animals that received (1) no viral cDNA complexes, (2) AAV without the promoter and reporter gene, or (3) the CMV-hgφ gene constructs that were also processed for lacZ histochemistry.

Light microscopic examination of the eyes that received the CMV-lacZ test virus and evaluated at the 2-week injection time point showed β-Gal heavily labeled the optic nerve head and adjacent retrobulbar optic nerve. However, no histochemical labeling of β-Gal was detected in the optic nerve at 3 months, 6 months, or 1 year. β-Gal labeling of nerve fiber bundles was best seen between foci heavily labeled by β-Gal and unlabeled foci of the retrobulbar nerve. In addition, blood vessels of the optic nerve and glial cells expressed blue -galactosidase reaction product. Glial cells that were immunolabeled for CA II had similar morphologic features as those expressing lacZ, thus suggesting that these lacZ-positive cells were ohgodendrocytes. Similarly, the morphologic characteristics of cells that were immunolabeled for GFAP were similar to some of those expressing lacZ, suggesting that these lacZ-positive cells were astrocytes. While double labeling of lacZ and GFAP or CA II was difficult to visualize, the double labeling of GFAP and lacZ in an astrocyte may be appreciated somewhat in a cell that appeared blue-black25 rather than the blue seen for lacZ and the brown seeen with GFAP immunoperoxidase. Histochemical labeling for lacZ was negative in all optic nerves examined three months to one year after injection of the viral reporter gene constructs. However, immunochemical staining for lacZ detected β-galactosidase in all five of the optic nerves studied as long as one year after a single intraocular injection of the viral cDNA complexes, although the number of positive cells at this late time period was clearly reduced relative to that seen at 2 to 4 weeks after injection. At one year, lacZ-positive cells, immunolabeled dark blue by alkaline phosphatase, were seen in the perivascular space and included glial cells of the interstitial optic nerve. The 1- year optic nerve control specimens with the primary antibody omitted from the alkaline phosphatase immunostaining protocol showed no immunolabeling. Since the number of positive cells was clearly reduced at one year, transmission electron microscopy coupled with immunogold was used to morphologically identify β-galactosidase positive cells rather than use dual labeling at the light microscopic level, as done for the earlier time points. At this one-year time point, transmission electron microscopy revealed heavy immunogold labeling for lacZ in ohgodendrocytes, astrocytes, fibers, and endothelial cells of the optic nerve head and adjacent retrobulbar optic nerve. Histopathologic analysis of the eyes of control animals that received no viral cDNA complexes, or AAV without the promoter and reporter gene elements, showed no β-galactosidase staining in any fibers or cell types of the optic nerve. Demyelination, reactive gliosis, and inflammatory cells were absent at any time point, including one year after injection, thereby suggesting the absence of previous immune-mediated tissue damage from the recombinant viral injections. Controls with the primary antibody omitted from the immunogold protocol had scant background particles in the optic nerve. Additional controls with the β-galactosidase antibody preabsorbed with the purified β-galactosidase protein showed no immunogold staining, thereby proving that immunogold labeling of the β- galactosidase in the optic nerve was due to the viral gene inoculation of lacZ. While β-Gal staining of the optic nerve was apparent in eye cups, β-Gal labeling of the retina was not visible in any of our animals by visual inspection of the eye cups with the naked eye or with the 10 magnification of the dissecting microscope. For orientation purposes, the guinea pig retina was stained with toluidine blue. LacZ histochemical analysis of unstained retina from eyes that received the lacZ viral constructs demonstrated that most cells of the ganglion cell layer were positive for β-galactosidase at two weeks. Diffuse β-Gal labeling of the outer retina was also evident at this time point. Retinas injected with the CMV-hgφ viral constructs that served as controls for the histochemical labeling of CMV-lacZ-injected eyes showed some very mild endogenous histochemical staining for β-galactosidase in the outer retina, supporting detection of endogenous outer nuclear layer activity. Confocal fluorescent microscopic examination for hgφ revealed hgφ fluorescence in cells of the ganglion cell layer four weeks after injection of the hgφ viral constructs. No signal in this cell layer was detected in eyes that received no viral cDNA complexes, the AAV without the promoter and reporter gene elements or thelacZ gene construct. However, autofluorescence of the outer retina was seen in both hgφ-injected and control eyes.

At three months after injection, lacZ histochemical analysis revealed some positively labeled cells in the outer nuclear layer, while ganglion cell labeling was much weaker than earlier. At six months to one year after injection, the retina was negative for lacZ histochemical staining; however, lacZ immunogold staining was seen in ganglion cells of the retina at one year.

Indicative of transcription of the transferred gene, cellular mRNA expression of the reporter lacZ was readily detected in cells of the ganglion cell layer. Two weeks after intravitreal injections with the CMV-lacZ viral constructs, the brown mRNA-derived reaction product labeled cells of the ganglion cell layer. Colabeling of blue lacZ protein and brown mRNA was seen in ganglion cells. In addition, cells that appeared to contain only the brown mRNA reaction product were seen adjacent to cells that appeared to contain only the blue β-galactosidase reaction product in the ganglion cell layer. The controls, with omission of the RT or PCR primers, showed only the blue lacZ staining.

5.2 EXAMPLE 2- SOD SUPPRESSION OF OPTIC NEURITIS

The protective effect on experimental optic neuritis of in vivo scavenging of superoxide by viral mediated gene transfer of rat manganese superoxide dismutase (MnSOD) and copper zinc superoxide dismutase (Cu/Zn SOD) genes was demonstrated in this example.

Adeno-associated AAV vector pTRUF was used to accept the MxSOD and Cu/Zn SOD cDNAs at the N tl and Sail sites. The resulting pTR-MnSOD and pTR-Cu/Zn SOD plasmids were amplified, then purified and packaged into rAAV. Five microliters of rAAS MnSOD or rAAV-Cu/Zn SOD were injected over the right optic nerve heads of SJ1/J mice. For controls, the left eyes received no injection. The mice were simultaneously sensitized for experimental allergic encephalomyelitis (EAE), the euthanized one month later. One month after inoculation with rAAV, levels of MnSOD immunogold in optic nerve cell types were increased by 25% to 97% and by 45% to 150% for Cu/Zn SOD immunogold.

Quantitative analysis of myelin sheath area revealed dismutation of superoxide by the MnSOD reduced demyelination by 14% (pO.Ol) while the Cu/Zn SOD increased demyelination by 24%> (p<0.05).

The eyes of MnSOD transfected mice had a mean myelin area of 28.35 x 10⁴ mm² that was greater (less demyelination) than a mean of 24.82 x 10⁴ mm² for the controls. The eyes of the Cu/Zn SOD transfected mice had a mean myelin area of 19.32 x 10⁴ mm² that was less than controls with a mean of 25.27 x 10⁴ mm². Optic disc edema was reduced 13% by MnSOD (p<0.05) while Cu/Zn SOD increased the cell count by 15% (p<0.05). Blood-brain barrier disruption was reduced by 33% with MnSOD (p<0.05), but extravasation of albumin immunogold was increased by 21% with Cu/Zn SOD (p<0.05).

In experimental optic neuritis, intracellular dismutation of superoxide is beneficial if SOD is overexpressed in the mitochondria (MnSOD), while overexpression of SOD in the cytosol and nucleus (Cu/Zn SOD) is detrimental.

5.3 EXAMPLE 3-CATALASE SUPPRESSION OF OPTIC NEURITIS

The following example illustrates that adenoviral mediated transfer of the catalase gene suppresses optic neuritis.

5.3.1 Recominant Adenovirus

The replication-deficient adenovirus (Ad) containing the human gene for catalase (CAT) and the vector without the catalase gene were provided by Ron Crystal, MD (New York Hospital-Cornell Medical Center, New York), and constructed as previously described (Erzurum, et al., 1993). The CAT complementary DNA was under the control of the adenovirus major late promoter. This construct was used to transfect human 293 cells (human embryonic kidney cells), and the resulting Ad-CAT virus was harvested, purified, and concentrated to a titer of lxl 0¹⁰ infectious plaque-forming units per milliliter.

5.3.2 Induction of EAE and Intraocular Injections

Experimental allergic encephalomyelitis was induced in 20 SJL/J mice, after they were sedated with methoxyflurane (Metofane; Pitman-Moore Inc, Terre Haute, Ind), by sensitization with homologous spinal cord emulsion in Freund complete adjuvant (Difco Laboratories, Detroit, MI), which was injected subdermally into the nuchal area. While the animals were under sedation, a 32-gauge needle attached to a Hamilton syringe was inserted through the pars plana. The needle tip was visualized in the vitreous with the use of the indirect ophthalmoscope, and it was positioned directly over the optic nerve head. Then 5 μL of Ad-CAT was injected into the vitreous of the right eyes of the mice. This intravitreal injection resulted in transient clouding of the cornea due to the sudden rise in intraocular pressure. For controls, the left eyes were injected with the replication-deficient adenovirus without CAT (n=10) or no virus (n=10).

5.3.3 Immunohistochemical Analysis

The mice were overdosed with pentobarbital sodium by intraperitoneal injection 1 month after viral and EAE inoculations. They were then perfused by cardiac puncture with fixative consisting of 4% paraformaldehyde in phosphate-buffered sodium buffer (pH 7.4), 0.1 mol/L, or for detection of in vivo H₂O , with a mixture consisting of cerium chloride, 2 mmol/L; 3-amino- 1,2,4-triazole, 10 mmol/L; the reduced form of nicotinamide adenine dinucleotide, 0.8 mmol/L; phosphate-buffered sodium buffer (pH 7.5), 0.1 mol/L; and 7%sucrose, followed by perfusion with the fixative. The eyes with attached optic nerves were dissected out and further processed by either of the following procedures: For H₂O₂ localization, tissue specimens were immersion- fixed in 2.5%) gluteraldehyde, then postfixed in 1% osmium tetroxide; sodium cacodylate hydrochloride buffer (pH 7.4), 0.1 mol/L; and 7% sucrose at 0°C, then dehydrated through an ethanol series to propylene oxide, infiltrated, and embedded in epoxy resin that was polymerized at 60°C overnight. For immunohistochemical analysis, tissue specimens were postfixed in 5% acrolein; sodium cacodylate hydrochloride buffer (pH 7.4), 0.1 mol/L; and 7% sucrose, then dehydrated through an ethanol series and embedded in resin (LR White resin; Ted Pella, Redding, Pa) that was polymerized at 50°C overnight. Semithin longitudinal sections (0.5 μm) of the optic nerve head and retro bulbar nerve were stained with toluidine blue for light-microscopic examination. Ultrathin sections (90 nm) were placed on nickel grids for immunohistochemical analysis.

Nonspecific binding of antibodies was blocked by floating the grids on either 5% normal goat serum in triethanolamine-buffered sodium (pH 7.2), 0.01 mol/L, with polysorbate 20 for 30 minutes for catalase immunostaining, or 2% teleost gelatin and 2% nonfat dry milk in triethanolamine-buffered sodium (pH 7.2), 0.01 mol/L, with polysorbate 20 for 30 minutes for albumin immunostaining. They were then reacted with rabbit anti-CAT antibodies or with rabbit antialbumin antibodies, respectively, in the same buffer for 2 hours at room temperature. After washes in phosphate-buffered sodium, 0.1 mol/L, the grids were reacted with the secondary goat antirabbit IgG antibodies conjugated to 10 nm of gold for 1 hour at room temperature. After washes in buffer, grids were rinsed in deionized water. For examination by low-magnification transmission electron microscopy, the immunogold particles were enlarged by silver enhancement using a kit (Ted Pella), according to the manufacturer's specifications. To check for nonspecific binding of the secondary antibody, control grids were incubated in the buffer, followed by the gold-labeled antibody. Immunolabeled and control specimens were photographed by transmission electron microscopy without poststaining.

5.3.4 Morphometric Analysis

Morphometiϊc analysis was performed in a masked manner, as previously described. Briefly, images of toluidine blue-stained sections of the optic nerve were captured with a video camera mounted on a light microscope, and the digital image was entered into computer memory. After initial calibration with a stage micrometer, the optic nerve head areas were manually traced using the National Institutes of Health (Bethesda, Md) image software and a computer (Macintosh; Apple Computer, Inc, Cupertino, Calif). The number of glial cells and inflammatory cells in the retrobulbar optic nerve were also quantitated by thresholding of the darker staining cell nuclei. Cell-specific catalase activity and extiavasated serum albumin immunogold were similarly quantitated.

The immunolabeled sections were examined without poststaining using a transmission electron microscope (H-7000; Hitachi Ltd, Tokyo, Japan) operating at 75 kV. Photographs were made at a magnification of 2500. Ten micrographs of each cell type were taken of each optic nerve. The negatives were digitized into computer memory using a scanner (Umax; Umax Data Systems, Fremont, Calif). Silver-enhanced immunogold particles and H2O2 reaction products were enlarged to a final magnification of 7500, thresholded, and counted with the software and computer system. Cell-specific catalase activity was quantitated by counting the number of silver-enhanced immunogold particles in endothelial cells, astroglial cells, oligodendroglial cells, axons, and microglial cells. Values were expressed as the mean SEM for each cell type. Mean particle counts for each nerve were obtained by taking the mean value of the 10 micrographs. Each mean value was expressed as the number of particles per unit area. The extent of demyelination was quantitated by threshold measurements of the myelin sheaths that were derived from the axonal micrographs for each optic nerve. Increases in the myelin sheath area (less demyelination) thereby indicated a beneficial treatment effect.

Grouped t tests were used to assess differences in the myelin areas, optic nerve head areas, optic nerve cell counts, and immunogold and H₂O₂ particle counts between the CAT- transduced right eyes and the control left eyes and between the left eyes injected with the empty adenovirus and the left eyes that received no ocular injection.

5.3.5 Cellular Levels of Catalase A prerequisite for demonstrating CAT-mediated suppression of EAE is the presence of increased levels of intracellular catalase in transduced tissues. No differences in catalase activity were seen between the control left eyes that received either the adenovirus injection without CAT or the left eyes that received no viral injection. One month after a single ocular injection of recombinant adenovirus, the levels of catalase immunogold in transduced right optic nerves from animals with EAE were significantly increased compared with the contialateral left optic nerves (FIG. 5A). Greater than 2-fold increases of catalase immunogold were seen in endothelial cells (2.50-fold, with CAT-inoculation mean immunogold particles, expressed per area of 6105 μm², were 17530 vs 7010 for the contialateral control nerves; P<.01) and in astrocytes (2.32-fold, 1496 vs 645; P<.01). These cell types had the highest levels of CAT transduction. Catalase immunogold labeling was also significantly increased in axons by 1.95-fold (11529 vs 5912; P<.01) and in oligodendroglia by 1.81-fold (14712 vs 8115; P<.01) compared with the contialateral control optic nerves. Whereas catalase immunogold levels were also increased in microglia by 1.45-fold (13916 vs 9614), these differences were not significant (P>.05). However, microglia had the highest endogenous levels of CAT of all cell types in the control optic nerves. Representative transmission electron micrographs of the optic nerve inoculated with Ad-CAT showed more catalase immunogold than in the control nerves inoculated with Ad. Clearly, substantially higher levels of catalase activity were achieved with CAT inoculation.

5.3.6 Demyelation In experimental optic neuritis, loss of the myelin sheaths that envelope axons is a hallmark of the histopathologic features at the ultrastructural level. Transmission electron microscopy of the optic nerve revealed that all animals sensitized for EAE exhibited foci of demyelination, naked axons, and axons enveloped by thin sheaths of myelin that were suggestive of remyelination. Mononuclear inflammatory cells and reactive astroglial cells comprised the optic nerve cellular infiltrate that predominantly involved the retrobulbar optic nerve. No evidence of myelin injury induced by the intravitreal injection was found. The left eyes that received the empty adenovirus had a mean myelin area of 26.01.5104/μm² vs 25.00.6104/μm² for uninjected left eyes (P>.05). Indicative of the suppression of demyelination by Ad-CAT delivery, however, CAT-inoculated optic nerves had 30% more myelin (less demyelination), with a mean myelin area of 37.02.0104/μm² vs 6.01.5104/μm² (P<.01) for the control left eyes that received the empty Ad (FIG. 5B). Representative transmission electron micrographs of the optic nerve inoculated with Ad-CAT showed less demyelination than the controls. Therefore, gene transfer of catalase achieved therapeutic protection from EAE-induced demyelination.

5.3.7 Optic Disc Edema

Optic disc edema, seen in about 40%> of patients with acute optic neuritis, was evident in animals with EAE. Lateral displacement of the peripapillary retina and filling of the optic cup indicated optic disc edema at the light-microscopic level. The peripapillary Retinas of SJL/J mice that are highly susceptible to the induction of EAE also showed a genetically induced degeneration of photoreceptors, with the outer nuclear layer reduced to a single cell layer that was symmetric between the right and left eyes. Ultrastructurally, intracellular edema of unmyelinated axons contributed to the optic nerve head swelling. These histopathologic features were seen to some degree in both CAT-transduced nerves and contialateral control nerves. In addition, we found no evidence of glaucomatous injury. There was no cupping, smaller optic nerve head areas, induced by the transient rise of intraocular pressure following the intravitreal injection. The left eyes that received the empty adenovirus had a mean optic nerve head area of 4.20.2104 μm vs 4.20.2104 μm for uninjected left eyes (P>.05). On the other hand, CAT delivery by adenovirus reduced optic disc edema by 25%), with a mean optic head nerve area of 3.20.3104 μm vs 4.20.2104 μm for the control left eyes that received the empty adenovirus (FIF. 5C). These differences were significant (P<.05). Thus, EAE-induced swelling of the optic nerve head was reduced by CAT inoculation. 5.3.8 Optic Nerve Cell Count

For all groups, light-microscopic evaluation of the myelinated segment of the optic nerve, commencing just posterior to the lamina scleralis, revealed foci of inflammatory cells and reactive astroglial cells. Comparisons of the control left eyes that received the adenovirus inoculation without CAT had a mean optic nerve cell count of 21816 cells 10⁵ μm² vs 21122 cells 10⁵ μm² for the left eyes that received no viral inoculation. This difference was not significant, thereby suggesting that adenovirus did not increase the inflammatory response in the EAE nerve. However, Ad-CAT inoculation reduced the optic nerve cell count by 26% to a mean value of 16115 cells 10⁵ μm² vs 21816 cells 10⁵ μm² for the control left eyes that received the empty adenovirus (FIF. 5D). These differences were significant (P<.05).

5.3.9 BBB Disruption

Disruption of the BBB, a hallmark of both experimental and human optic neuritis, was seen in all animals sensitized for EAE. In vivo evaluation of the BBB by contrast-enhanced magnetic resonance imaging reveals enhancement of the optic nerve in most patients with acute optic neuritis and in all animals with acute EAE. A standard marker of BBB disruption is the extravasation of serum albumin, which is detected by immunolabeling. Transmission election microscopy of the optic nerves revealed albumin immunogold labeling in all animals with EAE. Extiavasated albumin immunogold in the perivascular compartment located the foci of BBB disruption in EAE. Albumin immunogold confined to the intravascular compartment indicated normal integrity of the BBB. Comparisons of the control left eyes that received the adenovirus inoculation without CAT showed a mean of 656121 extiavasated immunogold particles per 2.6x10⁶ μm² compared with 54093 particles per 2.6x10⁶ μm² for the left eyes that received no viral inoculation. Although this difference was not significant (P>.05), it showed a trend suggesting that adenovirus itself may increase BBB disruption in the EAE optic nerve. On the other hand, adenovirally delivered CAT reduced disruption of the BBB by 61% to a mean value of 25639 extiavasated immunogold particles per 2.6x10 μm compared with 656121 particles per 2.6x10⁶ μm² for the control left nerves that received the empty adenovirus (FIG. 5E). These differences were significant (P<.05). Representative transmission electron micrographs of the optic nerve inoculated with Ad-CAT show less extiavasated serum albumin than the control left optic nerves, where a marked accumulation of extiavasated albumin immunogold in the perivascular space is evident. Therefore, CAT inoculation markedly improved BBB integrity. 5.3.10 Reduced Levels of H₂O₂

The perfusion of animals with cerium chloride forms an electron-dense precipitate, cerium perhydroxide, in the presence of endogenously generated H₂O₂. This reaction product was seen predominantly in a perivascular distribution in animals with EAE. It was also seen along the apical processes of endothelial cells in normal, unsensitized animals. In the interstitial optic nerve of animals with EAE, the reaction product also surrounds infiltrating inflammatory cells. Decreased in vivo levels of H O₂ were seen with Ad-CAT inoculation. Mean particle counts in the optic nerve head were reduced by 81% in CAT-inoculated nerves to a mean of 116 particles per 2.6x10 μm vs 5921 per 2.6x10 μm for the control nerves that received the empty adenovirus (P<.05) (FIG. 5F). In the retrobulbar optic nerve, reaction product counts were reduced by 65% to a value of 8135 with CAT inoculation vs 23170 for control nerves that received the empty adenovirus (P>.05). In the optic nerve sheath, particle counts were reduced 52%) to a mean of 43396 with catalase inoculation vs 900141 in the control nerves that received the empty adenovirus (P<.05). Representative transmission electron micrographs of the optic nerve head inoculated with Ad-CAT exhibited less H₂O -derived reaction product than the control nerves.

5.3.11 Discussion Gene delivery and expression have been demonstrated in many mammalian tissues, including retina, neural tissues, and endothelial cells, but few reports describe gene transfer to the optic nerve. Structural injury to oligodendroglial cells and dysfunction of endothelial cell permeability lead to demyelination and disruption of the BBB, which are the predominant pathogenic tissue alterations of optic neuritis, EAE, and MS. The viral promoters (adenovirus or cytomegalovirusl 1) drove the transgene expression that doubled catalase levels in each of these important optic nerve cell types. Although the peripapillary retinas of EAE-susceptible SJL/J mice also showed a genetically induced degeneration of photoreceptors, the retinal structure was symmetric between the right and left eyes, and the ultrastructure of the optic nerves appeared normal. Consequently, the photoreceptor abnormality played no role in the differences in optic nerve morphometric measurements obtained between CAT-injected right eyes and control left, eyes. The increased cellular levels of catalase protected against ROS-induced optic nerve injury in the EAE animal model of MS. Endothelial cells comprising the BBB are the first line of defense against mediators of EAE injury to myelin and oligodendroglia. Thus, the restoration of BBB integrity is an important first step in limiting the pathologic effects of EAE. The adeno viral-mediated doubling of catalase levels in endothelial cells suppressed the disruption of the BBB by 61%). This restoration of BBB integrity might also have a suppressive effect on EAE by restricting not only H₂O₂ but also other ROS mediators of damage from access to the optic nerve. Hydrogen peroxide is a strong oxidant that can diffuse from the sites of generation in the perivascular space and induce peroxidation of myelin and oligodendroglia at remote sites in the interstitial optic nerve. Oligodendroglia are particularly vulnerable to the effects of H₂O₂. This cell type suffers the greatest injury in both EAE and MS, culminating in the classic demyelination. Reductions in perivascular ROS, coupled with the viral transduction of 2-fold increases in cellular levels of catalase in oligodendroglia, partially protected these important cells from the adverse effects of H₂O₂ released into the microenvironment by the inflammatory process, thereby reducing demyelination by 30%). It was surprising to find that transgene expression and the suppressive effects of CAT gene transfer on experimental optic neuritis with adenovirus were comparable to those seen with AAV-mediated gene transfer when studied one month after inoculation.

One factor contributing to this result was that the adeno viral titer was 10³ times higher than that reported in a study using recombinant AAV. Whereas adenovirus has the theoretical advantage of faster cellular transduction, it has the disadvantage of inciting an inflammatory response that contributes to short-lived cellular transduction, often lasting two weeks. Comparisons of the optic nerve cell counts between the control left eyes that received the adenovirus inoculation without CAT and the control left eyes that received no viral inoculation were comparable, and they showed no significant differences, thus suggesting that adenovirus did not substantially increase the inflammatory response in the EAE-induced optic nerve. Nevertheless, transgene expression with adenoviral vectors incites inflammation in normal tissues, and it is undetectable two months after inoculation. Adenovirus vectors, however, will persist longer in animals that do not mount an effective inflammatory response. Persistent adenoviral transduction is impaired by immune mediators such as nitric oxide that are generated by the inflammatory response induced by adenovirus reductions in inflammation induced by ROS scavenging with catalase may prolong the duration of expression of this transgene product in EAE-affected optic nerves one month after adenoviral inoculation. Unlike adenovirus, AAV does not incite an inflammatory response; thus, it has provided long-term transgene expression at least as long as 11/2 years. For this reason, AAV is preferred for long-term transgene expression needed for optic nerve protection against future ROS injury by the recurrence of optic neuritis. The comparably small size (21 nm) of the AAV particle, however, limits the size of packaged genes for transfer with AAV to about 4.5 kilobases (kb). Although this presented no problem for insertion of the 2-kb CAT, the insertion of larger gene(s), such as the myelin basic protein (MBP), its promoter, or both, is too long for incorporation into AAV.

Transfer of the MBP gene has the potential to promote remyelination by oligodendroglia that persist in chronically demyelinated nerves, such as those of patients left with poor visual acuity six months or more after an attack of optic neuritis. The larger capacity of recombinant adenovirus may accommodate this relatively larger gene, whose transduction in patients blinded by optic neuritis may improve their level of visual function. This newly formed myelin should persist in these chronically demyelinated optic nerves because the inflammatory response has long since subsided. In demyelinated optic nerves with active inflammation, however, ROS scavenging by catalase may also promote remyelination by limiting the damage of myelin basic protein in impaired but not destroyed oligodendroglia.

Results show that either viral vector-adenovirus or AAV-may be used to transfer small genes such as CAT to suppress demyelination and perhaps promote remyelination. Because many advances in therapy for MS were first tested in the EAE animal model our findings of the suppression of experimental optic neuritis with CAT gene transfer suggests that this form of therapy may be useful in patients with acute optic neuritis.

5.4 EXAMPLE 4-CATALASE AAV SUPPRESSION OF EAE 5.4.1 VECTOR PREPARATION

The AAV vector, pTRUF (Zolotukin et al, 1996), was used to accept catalase cDNA at the Notl and SaR sites. Catalase cDΝA was obtained from Chiron. The resulting pTR-Cat plasmid (FIG. 1, restriction map) was then amplified and purified by using cesium chloride gradient centrifugation. The resulting rAAV-Cat construct was regulated by a cytomegalovirus (CMV) immediate early promoter. This pTR-Cat plasmid DΝA was packaged into rAAV by transfection into 293 cells using standard procedures. The resultant rAAV-packaged pTR-Cat was assayed for rAAV by an infectious center assay and gave a titer of 1 x 10⁸ infectious units/ml. It also was tested for contaminating Adenovirus by plaque assay and wild-type AAV by infectious center assay. Both potentially contaminating viruses were found to be below detection limits, <5 orders of magnitude lower than rAAV.

5.4.2 INDUCTION OF EAE AND INTRA-OCULAR INJECTIONS

Experimental allergic encephalomyelitis was induced in 20 SJL/J mice by sensitization with homologous spinal cord emulsion in complete Freund's adjuvant (Difco) that was injected subdermally into the nuchal area. Five microliters of rAAV-Cat were injected over the right optic nerve heads of SJL/J mice. For controls, the left eyes receive rAAV containing the green fluorescent protein (gφ) gene in place of the catalase gene. The mice were simultaneously sensitized to develop EAE (Raine, 1985).

5.4.3 IMMUNOHISTOCHEMISTRY

One month after viral and EAE inoculations, the mice were overdosed with sodium pentobarbital. They were then perfused by cardiac puncture with fixative consisting of 4% paraformaldehyde in 0.1 M PBS buffer (pH 7.4) or, for detection of in vivo H₂O₂, with a mixture consisting of 2 raM cerium chloride, 10 mM 3-amino-l,2,4-triazole, 0.8 mM NADH, 0.1 M PBS buffer (pH 7.5), and 7% sucrose followed by perfusion with the fixative (Guy et al, 1994a). The eyes with attached optic nerves were dissected out and further processed by either of the following procedures: (i) for H O₂ localization, tissue specimens were immersion fixed in 2.5%> gluteraldehyde, postfixed in 1% osmium tetroxide, 0.1 M sodium cacodylate-HCI buffer (pH 7.4), 1% sucrose in the cod, and then dehydrated through an ethanol series to propylene oxide, infiltrated, and embedded in epoxy resin that was polymerized at 60°C overnight; or (ii) for immunocytochemistry, tissue specimens were postfixed in 5.0%> acrolein, 0.1 M sodium cacodylate-HCl buffer (pH 7.4), and 7%> sucrose and then dehydrated through an ethanol series and embedded in LR White (Ted Pella, Redding, PA) that was polymerized at 50°C overnight.

Semi-thin longitudinal sections (0.5 μm) of the optic nerve head and retrobulbar nerve were stained with toluidine blue for light microscopic examination. Ultrathin sections (90 nm) were placed on nickel grids for immunocytochemistry. Nonspecific binding of antibodies was blocked by floating the grids on either (i) 5%> normal goat serum in 0.01 M Tri-buffered saline (pH 7.2) with Tween-20^® (TBST) for 30 min. for catalase immunostaining, or (ii) 2% teleost gelatin and 2% nonfat dairy milk in 0.01 M TBS (pH 7.2) with TBST for 30 min for albumin immunostaining. They were then reacted with rabbit anti-catalase antibodies or with rabbit anti- albumin antibodies, respectively, in the same buffer for 2 hr. at room temperature. After washes in 0.1 M PBS, the grids were reacted with the secondary goat anti-rabbit IgG antibodies conjugated to 10-nm gold for 1 hr. at room temperature. After washes in buffer, grids were rinsed in deionized water. For examination at low magnification transmission electron microscopy, the immunogold particles were enlarged by silver enhancement using a kit (Ted Pella) according to the manufacturer's specifications. To check for nonspecific binding of the secondary antibody, control grids were incubated in the buffer, followed by the gold-labeled antibody. Immunolabled and control specimens were photographed by transmission election microscopy without poststaining.

5.4.4 MORPHOMETRIC ANALYSIS

Morphometiic analysis was performed in masked fashion as described by Qi et al, (1997). Briefly, images of toluidine blue stained sections of the optic nerve were captured with a video camera mounted on a light microscope and then the digital image was entered into computer memory. After initial calibration with a stage micrometer, the optic nerve head areas were manually traced using the NIH IMAGE software and a Macintosh Computer (Apple, Cupertino, CA). The number of glial cells and inflammatory cells in the retrobulbar optic nerve were quantitated also by thresholding of the darker staining cell nuclei. Cell-specific catalase activity and extravasated serum albumin immunogold were similarly quantitated. The immunolabeled sections were examined without poststaining by using a Hitachi H-7000 transmission electron microscope (Tokyo, Japan) operating at 75kV. Photographs were made at a magnification of χ2,500. Ten micrographs were digitized into computer memory by using a UMAX scanner (UMAX Data Systems, Fremont, CA). Silver-enhanced immunogold particles and H₂O reaction products were enlarged to a final magnification of χ7,500, thresholded, and counted with the software and computer system.

Cell-specific catalase activity was quantitated by counting the number of silver-enhanced immunogold particles in endothelial cells, astroglial cells, oligodendroglial cells, axons, and microglial cells. Values were expressed as the mean ± standard error of mean for each cell type. Mean particle counts for each nerve were obtained by taking the mean value of the 10 micrographs. Each mean value was expressed as the number of particles per unit area. The extent of demyelination was quantitated by threshold measurements of the myelin sheaths that were derived from the axonal micrographs for each optic nerve. Increases in myelin sheath area (less demyelination), thereby indicated a beneficial treatment effect. Grouped t tests were used to assess differences in the myelin areas, optic nerve head areas, optic nerve cell counts, immunogold, and H₂O₂ particle counts between the catalase-transduced right eyes and the control left eyes.

5.4.5 CELLULARLEVELS OF CATALASE

A prerequisite for demonstration of catalase-mediated suppression of EAE is the presence of increased levels of intracellular catalase is transduced tissues (Erzurum et al, 1993).

One month after inoculation of rAAV, the levels of catalase in transduced optic nerves were increased almost two-fold in most cell types (FIG. 2A). The highest levels of catalase transduction were seen in axons with a 2.13 -fold increase (mean immunogold particles were

151 ± 23 per area of 6 x 10⁵ μm with catalase inoculation vs. 71 ± 12 for gφ inoculation, P < 0.05) and in ohgodendrocytes with a 1.91-fold increase (128 ± 20 vs. 67 ± 12, P < 0.05).

The levels of catalase were increased by 1.80-fold in astrocytes (135 ± 21 vs. 75 ± 8, P < 0.05) and by 1.85-fold in endothelial cells (102 ± 11 vs. 55 ± 12, < 0.05). While the levels of catalase immunogold also were increased in microglia by 1.43-fold (185 ± 20 vs. 129 ± 28), these differences were not statistically significant. Transmission electron micrographs (x2,500) of the optic nerve inoculated with rAAV-Cat showed more catalase immunogold than in the control nerves inoculated with rAAV-gφ. Clearly, substantially higher levels of catalase activity were achieved with rAAV-Cat.

5.4.6 DEMYELINATION In EAE, as well as MS, loss of the myelin sheaths that envelop axons is a hallmark of pathology at the ultrastructural level (Raine, 1985). Transmission electron microscopy of the optic nerve revealed all animals sensitized for EAE exhibited foci of demyelination, including naked axons. Axons enveloped by thin sheaths of myelin were frequently seen and suggested limited demyelination. Mononuclear inflammatory cells and reactive astroglial cells comprised the optic nerve cellular infiltrate that predominantly involved the retrobulbar optic nerve. Indicative of the suppression of demyelination by catalase gene delivery with rAAV, catalase inoculated nerves exhibited a mean myelin area of 23 ± 3 x 10⁴ per μm, 38%> more myelin (less demyelination) than the contialateral control nerves with a mean of 37 ± 1 x 10⁴ per μm (P < 0.01) (FIG. 2B). Transmission electron micrographs (x2,500) of the optic nerve inoculated with rAAV-Cat had less demyelination than the controls inoculated with rAAV-gφ. Therefore, rAAV gene transfer of catalase achieved therapeutic protection from EAE induced demyelination.

5.4.7 OPTIC DISC EDEMA

Optic disc edema, seen in s50%) of MS patients with acute optic neuritis (Beck et al, 1992), was evident in EAE animals in which lateral displacement of the peripapillary retina and filling of the optic cup indicated optic disc edema at the light microscopic level. Ultrastructural analysis revealed intracellular edema of unmyelinated axons contributing to the optic nerve head swelling. These histopathologic features were seen to some degree in both catalase-transduced nerved and contialateral control nerves. Catalase gene delivery by rAAV-Cat reduced optic disc edema, by 20%, with a mean optic nerve head area of 3.00 ± 0.10 x 10⁴ μm vs. 4.20 ± 0.30 x 10⁴ μm for rAAV-gφ-injected eyes (FIG. 2C). These differences were statistically significant (P < 0.01). For catalase gene-treated optic nerves, rAAV-Cat reduced EAE induced swelling of the optic nerve head.

5.4.8 OPTIC NERVE CELL COUNT

For all groups, light microscopic evaluation of the myelinated segment of the optic nerve, commencing just posterior to the lamina scleralis, revealed foci of inflammatory cells and reactive astroglial cells. The rAAV-Cat gene inoculation reduced the optic never cell count by 34%) to a mean value of 140 ± 9 cells per 10⁵ μm compared with 211 ± 22 cells per 10⁵ μm for the rAAV-gφ-injected eyes (FIG. 2D). These differences were statistically significant ( < 0.01). Thus, the rAAV-Cat construct reduced the population of cells comprising the associated cellular infiltrate in the myelinated optic nerve. 5.4.9 BBB DISRUPTION

Disruption of the BBB, a hallmark of MS (Katz et al, 1993), was seen in all animals sensitized for EAE. In vivo evaluation of the BBB by contrast enhanced MRI reveals enhancement of the optic nerve in most patients with acute optic neuritis and in all animals with acute EAE. A standard marker of BBB disruption is the extravasation of serum albumin that is detected by immunolabeling. Transmission electron microscopy of the optic nerves revealed albumin immunogold labeling in all animals with EAE. Extiavasated albumin immunogold labeling in the perivascular compartment located the foci of BBB disruption in EAE. Albumin immunogold confined to the intravascular compartment indicated normal integrity of the BBB. rAAV-delivered catalase genes reduced disruption of the BBB by 64%, with a mean value of 193 ± 15 extravasated immunogold particles per 2.6 x 10⁶ μm compared with the rAAV-gφ injected nerves with a mean value of 540 ± 93 extravasated particles (FIG. 2E). These differences were statistically significant (P < 0.05). Transmission electron micrographs (x3.500) of the optic nerve inoculated with rAAV-Cat exhibited less extravasated serum albumin than the controls (x4.000) inoculated with rAAV-gφ in which a marked accumulation of extravasated albumin immunogold in the perivascular space is evident. Thus, catalase gene introduction markedly improved BBB integrity.

Thus it is important in human therapies to target the BBB for protection against reactive oxygen species (ROS). For anti-ROS expression in endothelial cells, the use of a human VEGF promoter is expected to provide advantages in delivering the anti-ROS genes to endothelial cells. Regulatory elements of the VEGF receptor-2 (Flk-1) gene that mediates endothelial-specific express have been reported (Kappel, et al., 19XX). A second candidate promoter for delivery to endothelial cells is the eNOS 5' sequence.

5.4.10 REDUCED H₂O₂ LEVELS

Perfusion of animals with cerium chloride results in an electron dense precipitate in the presence of endogenous H₂O . Cerium perhydroxide reaction product was seen predominantly in a perivascular distribution in EAE animals. It was also seen along the apical processes of endothelial cells in normal unsensitized animals. In the interstitial optic nerve of EAE animals, the reaction product also surrounds infiltiating inflammatory cells. Decreased in vivo levels of H₂O₂ were seen with rAAV catalase gene inoculation. Mean particle counts in the optic nerve head were reduced by 61 % in the rAAV-Cat inoculated nerves to a mean of 97 ± 43 particles per 2.6 x 10⁶ μm vs. 249 ± 64 for the rAAV-gφ injected nerves (P > 0.05). In the retrobulbar optic nerve, reaction product counts were reduced by 66%> to a value of 41 ± 23 with catalase gene inoculation vs. 119 ± 60 for control nerves (P > 0.05). In the optic nerve sheath, particle counts were reduced 75% to a mean of 142 ± 48 with catalase inoculation vs. 421 ± 107 in the control nerves ( < 0.05). Transmission electron micrographs (x3.000) of the optic nerve head inoculated with rAAV-Cat exhibited less H₂O derived reaction product than the controls inoculated with rAAV-gφ in which higher levels of cerium perhydroxide particles are evident in the perivascular space.

5.4.11 DISCUSSION

Structural or functional injury to two cell types, endothelial cells and oligodendroglial cells, accounts for the predominant pathogenic tissue alterations leading to disruption of the BBB and demyelination, the hallmarks of both EAE and MS. Endothelial cells comprising the BBB are the first line of defense against mediators of EAE injury to myelin, axons and oligodendroglia. Thus, restoration of BBB integrity is an important first step in limiting EAE pathology. Viral vector introduction of catalase genes into endothelial cells suppressed disruption of the BBB by 64%>. Although H₂O is a strong oxidant that can diffuse from the sites of generation in the perivascular space and induce peroxidation of lipids in axonal membranes and myelin at remote sites in the interstitial optic nerve, restoration of BBB integrity might also have a suppressive effect on EAE by restricting other mediators of damage from access to the optic nerve. The marked reductions in perivascular cerium perhydroxide reaction product in catalase transduced nerves suggest that increased intracellular levels of catalase in endothelial cells most likely scavenged H₂O₂, thereby contributing to restoration of BBB integrity in EAE animals.

While viral promoters drive transgene expression in several different cell types, promoters may be designed for cell-specific expression. Cell-specific promoters may have an advantage over the viral promoters by inducing a higher efficiency of transduction in targeted cells. When cell-specific promoters are utilized in the treatment of EAE and eventually MS, protection of endothelial cells, oligodendroglia cells and axons is desirable. This may be accomplished with the use of three viral constructs, one with a cell-specific promoter for endothelial cells, one with a promoter for oligodendroglial cells (Chen et al, 1998), and a third with a neuronal promoter for expression in axons (Peel et al, 1997). Alternatively, these promoters may be linked to therapeutic genes in a single construct, although the size constraint of AAV may limit this approach. However, the inventors found that the CMV promoter with a broad range of expression doubled expression of catalase in all affected optic nerve cell types, with a significant impact on the suppression of EAE.

In previous protein injection studies, the integrity of the BBB limited the success of exogenous catalase suppression of EAE. While catalase had an overall suppressive effect on EAE, its lack of effectiveness during the initial stages of EAE was in part due to the BBB inhibition of CNS penetration of catalase. Only after extensive BBB disruption by the demyelinating inflammation of EAE, was catalase activity in the optic nerve significantly increased by the intraperitoneal injections. In addition, catalase protein has to be administered daily to maintain this increased activity.

Paradoxically, early restoration of BBB integrity allowed optic neuritis to recur due to the impaired ability of exogenous catalase protein to cross the once again intact BBB. This effect made the optic nerve again vulnerable to the effects of ROS, thereby contributing to relapses. Gene therapy with catalase avoids these problems by maintaining increased levels of intracellular catalase in the CNS after a single inoculation. If long term therapeutic levels are maintained in transduced cells and tissues, viral gene transfer is expected to suppress the relapses of EAE, and also to reduce the frequent recurrences of optic neuritis that often contribute to permanent and disabling visual loss (Optic Neuritis Study Group, 1997). Since axonal loss associated with multiple recurrences limits recovery of visual and neurologic function (Trapp et al, 1998), increased axonal levels of catalase following gene transfer may limit this irreversible sequela. While the effects of axonal rescue in demyelinated nerves by catalase are not completely elucidated, it is clear that viral mediated gene transfer of catalase suppressed demyelination and BBB disruption when administered prior to the onset of EAE.

For therapeutic efficacy, cellular expression of transgene product must persist for the duration of the disease process. These results show that either rAAV or adenovirus may be used to drive short term gene expression in the optic nerve for at least one month. However, longer term studies with adenoviral vectors have shown that transgene expression is undetectable two months after inoculation into skeletal muscle (Xiao et al, 1996), but may persist longer in animals with defective immune systems (Hoffman et al, 1997). In contrast, long term expression of rAAV transferred genes has been demonstrated in various tissues including brain (Kaplitt et al, 1994) (3-4 months) and muscle (Xiao et al, 1996; Kessler et al, 1996) (40 weeks to 1.5 years). Transduction in the optic nerve with rAAV persisted for at least two years after a single inoculation. Since many advances in the therapy of MS were first tested in EAE (Karussis et al, 1993), the present results showing suppression of EAE coupled with long term rAAV- mediated gene expression in the optic nerve indicates that rAAV is an effective vector for use in anti-ROS gene therapy of optic neuritis and MS.

A variety of ROS play a role in the pathogenesis of EAE (Okuda et al, 1998). Therefore, scavenging other ROS mediators, including peroxynitrite and nitric oxide, will also suppress EAE. In addition, passive transfer of inflammatory cells transfected with the immunomodulatory cytokines interleukin 4 or interleukin-10 that effect multiple mediators of tissue injury are also expected to suppress EAE.

Although the inventors have demonstrated H₂O₂ scavenging by catalase in the optic nerve, this nerve is a frequently involved site in EAE and MS, with optic neuritis often being the first clinical sign of MS (Beck et al, 1992). Therefore, the demonstration of optic nerve protection against EAE by virally mediated catalase gene delivery indicates that analogous CNS application has the potential to protect the brain and spinal cord in MS patients, particularly in those with a first demyelinating event who are at great risk for developing MS. Improvements in tissue-specific gene targeting after systemic administration, rather than locally invasive gene delivery, may increase the likelihood of acceptance of gene therapy for CND demyelinating disorders.

6.0 BRIEF DESCRIPTION OF THE SEQUENCES

Forward primer 5'-CTG GCG GTA ATA GCG AAG AGG-3' (SEQ ID NO:l) Reverse primer 5'GGT GTA GAT GGG CGC ATC3' (SEQ ID NO:2)

Catalase cDNA (SEQ ID NO:3) Mn SOD (SEQ ID NO:4) Cu/Zn SOD (SEQ ID NO:5)

7.0 REFERENCES

The following references, to the extent that they provide exemplary procedural or other details supplementary to those set forth herein, are specifically incorporated herein by reference. United States Patent 4,554,101, issued Nov. 19, 1985.

United States Patent 4,883,750, issued Nov. 28, 1989.

United States Patent 5,641,515, issued Jun. 24, 1997.

United States Patent 5,656,016, issued Aug. 12, 1997. United States Patent 5,725,871 , issued Mar. 10, 1998.

United States Patent 5,756,353, issued May 26, 1998.

United States Patent 5,780,045, issued Jul. 14, 1998.

Abuchowski, McCoy, Palczuk, Van Es and Davis, J Biol Chem., 252:3582-3586, 1977.

A\i et al, Hum. Mol Genet., 5:591-594, 1996. Beck, Cleary, Anderson, Keltner, Shults, Kaufman, Buckley, Corbett, Kupersmith and Miller, N. Engl J. Med, 326:581-588, 1992.

Berns et al, In: Virus Persistence, Mehay et al. (Ed.), Cambridge Univ. Press, pp. 249-265, 1982.

Bowern, Ramshaw, Clark and Doherty, J Exp. Med., 260:1532-1543, 1984. Brett and Rumsby, Neurochem. Int. , 23 :35-44, 1993.

Buller, Janik, Sebring, Rose, J Virol, 40(l):241-247, 1981.

Carter et al, In: The Parvoviruses, K.I. Berns (Ed.), Plenum, ΝY, pp. 67-128, 1983.

Cayouette and Gravel, Invest. Ophthalmol. Visual Sci., 37:2022-2028, 1996.

Chen, McCarty, Bruce, Suzuki and Suzuki, Gene Ther., 5:50-58, 1998. Crapo, Barry, Foscu and Shelburne, Am. Rev. Respir. Dis., 122:123-143, 1980.

Cukor et al, In: The Paroviruses, K.I. Berns (Ed.), Plenum, ΝY, pp. 33-66, 1984.

Erzurum, Lemarchand, Rosenfeld, Yoo and Crystal, Nucleic Acids Res., 21 :1607-1612, 1993.

Flannery, Zolotukhin, Vaquero, LaVail, Muzyczka and Hauswirth, Proc. Natl. Acad. Sci. USA, 94:6916-6921, 1997. Guy, Ellis, Hope and Rao, Arch. Ophthalmol, 107:1359-1363, 1989a.

Guy, Ellis, Hope and Rao, Curr. Eye Res., 8:467-477, 1989b.

Guy, Ellis, Hope and Rao, J. Free Rad. Biol Med, 2:349-357, 1986.

Guy, Fitzsimmons, Beck and Rao, Invest. Ophthalmol Visual Sci., 35:1114-1123, 1994a.

Guy, Ellis, Mames and Rao, Ophthalmic Res., 25:253-564, 1993. Guy, McGorray, Fitzsimmons, Beck, Mancuso, Rao and Hamed, Invest. Ophthalmol Visual Sci. , 35:3456-3465, 1994b. Heffner and Fracica, in Nitric Oxide and Radicals in the Pulmonary Vasculature, eds. Weir,

Archer and Reeves, pp. 105-133, 1996. Hermonat, Labow, Wright, Berns, Muzyczka, J Virol, 51(2):329-339, 1984. Hoffman, Maquire and Bennett, Invest. Ophthalmol. Visual Set, 38:2224-2233, 1997. Hoggan, Fed. Proc, 24:248, 1965.

Honegger, Krenger and Langemann, Neurosci. Lett., 98:327-332, 1989. Kaplitt, Leone, Samulski, Xiao, Pfaff, O'Malley and During, Nat. Genet., 8:148-154, 1994. Karussis, Lehmann, Slavin, Vourka-Karussis, Mizrachi-Koll, Ovadia, KaJland and Abramsky, Proc. Natl Acad. Sci. USA, 90:6400-6404, 1993. Katz, Taubenberger, Cannella, McFarlin, Raine and McFarland, Ann. Neurol. , 34:661 -669, 1993. Kessler, Podsakoff, Chen, McQuiston, Colosi, Matelis, Kurtzman and Byrne, Proc. Natl. Acad.

Sci. USA, 93:14082-14087, 1996. Kinnula, Crapo and Raivio, Lab. Invest., 73(1):3-19, 1995. Kyte and Doolittle, J. Mol Biol, 157(1):105-132, 1982. Lasic, Trends Biotechnol, 16(7):307-321, 1998.

Laughlin, Tratschin, Coon, Carter, Gene, 23(l):65-73, 1983.

Lossinsky, Badmajew, Robson, Moretz and Wisniewski, Acta Neuropathol , 78:359-371, 1989. Lusby and Berns, J Virol, 41 (2):518-526, 1982.

Maniatis et al, "Molecular Cloning: a Laboratory Manual," Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 1982.

McLaughlin, Collis, Hermonat and Muzyczka J Virol, 62:1963-1973, 1988. Mori and Fukatsu, Epilepsia, 33(6):994-1000, 1992. Muller et al, Cell, Biol, 9(3):221-229, 1990. Mulligan, Science, 260:926-932, 1993. Muzyczka, In: Current Topics in Microbiology and Immunology, Springer- Verlag, Berlin, 158:97-129, 1992. Okuda, Sakoda, Fujimura and Yanagihara, J Neuroimmunol , 81 :201-210, 1998. Optic Neuritis Study Group, Arch. Ophthalmol, 115:1545-1552, 1997.

Padmanabhan, Gudapaty, Liener, Schwartz and Hoidal, Am. Rev. Respir. Dis., 132:164-167, 1985.

Parks, Melnick, Rongey, Mayor, J Virol, 1(1):171-180, 1967. Paterson and Day, Am. J. Pathol, 52:251-263, 1982. Peel, Zolotukhin, Schrimsher, Muzyczka and Rier, Gene Ther., 4:16-24, 1997.

Qi, Guy, Nick, Valentine and Rao, Invest. Ophthalmol. Visual Sci, 38, 1203-1212, 1997.

Raine, In Handbook of Clinical Neurology, eds. Vinken, Bruyn and Klawans (Elsevier, New York), Vol. 3, 1985. Raine, J Neuroimmunol, 77:135-152, 1997.

Rao, Invest. Ophthalmol. Visual Sci. , 20: 159-172, 1981.

Remington's Pharmaceutical Sciences" 15th Edition, pages 1035-1038 and 1570-1580, 1996.

Rizzo and Lessell, Neurology, 38:185-190, 1988.

Ruuls, Bauer, Sontrop, Huitinga, Hart and Dijkstra, J. Neuroimmunol, 56:207-217, 1995. Samulski, Berns, Tan, Muzyczka, Proc. Natl. Acad. Sci. USA, 79(6):2077-2080, 1982.

Sarris, Smith, Shumway, Stinson, Oyer, Robbins, Billingham, Theodore, Moore and Katz, J Heart Lung Transplant, 13:940-949, 1994.

Schraufstatter and Cochrane, in The Lung: Scientific Foundations, 2^nd Ed., eds. Crystal, West, Weibel and Barnes, pp. 2251-2258, 1997. Sculier et al, J. Cancer Clin. Oncol. , 24(3):527-538, 1988.

Srivastava, Lusby, Berns, J Virol, 45(2):555-564, 1983.

Steinman, Adv. Immunol, 49:357-379, 1991.

Takenaga, Serizawa, Azechi, Ochiai, Kosaka, Igarashi, Mizushima, J. Controller Release, 52(l-2):81-87, 1998. Tanswell and Freeman, J. Appl Physiol, 63:343-352, 1987.

Tanswell and Freeman, New Horizons, 3:330-341, 1995.

Trapp, Peterson, Ransohoff, Rudick, Mork and Bo, N. Engl J. Med, 338:278-285, 1998.

Tratschin, Miller, Carter, J Virol, 51(3):611-619, 1984a.

Tratschin, West, Sandbank, Carter, Mol Cell Biol, 4(10):2072-2081, 1984b. Walker et al, Nucl Acid Res., 20(7):1691-1696, 1992.

Walther, David-Cu and Lopez, Am. J. Physiol, 269:L613-L617, 1995.

Warren and Ward, in The Lung: Scientific Foundations, 2" Ed., eds. Crystal, West, Weibel and Barnes, pp. 2279-2288, 1997.

Wispe, Warner, Clark, Dey, Neuman, Glasser, Crapo, Chang and Whitsett, J Biol. Chem., 267:23937-23941, 1992.

Wu and Dean, J Mol. Biol, 255(4):628-640, 1996.

Xiao, Li and Samulski, J. Virol, 70:8098-8108, 1996. Zolotukhin, Potter, Hauswirth, Guy and Muzyezka, J Virol, 70:4646-4654, 1996.

All of the compositions and 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 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.

Claims

WHAT IS CLAIMED IS:

1. Use of an rAAV composition comprising an rAAV that comprises a polynucleotide sequence encoding a mammalian catalase or superoxide dismutase polypeptide to reduce demyelation in an optic nerve.

2. The use of claim 1 wherein said rAAV comprises a promoter operative in endothelial and oligodenroglial cells.

3. The use of claim 2 wherein the promoter is CMV promoter.

4. The use of claim 1 wherein the rAAV composition is provided by injection.

5. The prophylactic use of the composition of claim 1 to suppress blood brain barrier disruption in a mammal having identified allergic encephalomyelitis.

6. The use of the composition of claim 5 that comprises a catalase expressing catalase in an amount effective to decrease axonal loss.

7. The use of claim 2 wherein the promoter is myelin basic protein promoter, platelet derived growth factor promoter (PDGF) or vascular endothelial growth factor (VEGF) promoter.

8. Use of the rAAV composition of claim 1 to scavenge reactive oxygen species (ROS) in a mammal suspected of having optic neuritis.

9. The use of claim 8 wherein the composition provides Mn superoxide dismutase to the optic nerve of said mammal.

10. The use of claim 8 wherein the composition provides Cu-Zn superoxide dismutase to the optic nerve of said mammal.

11. The use of claim 8 wherein the composition provides Mn superoxide dismutase and catalase to the optic nerve of said mammal.

12. Use of the composition of claim 1 to reduce the symptoms associated with a demyelating disease, said symptoms including optic disk edema, increase of optic nerve cell count, disruption of blood brain barrier integrity, increased levels of hydrogen peroxide, and demyelation of axons.

13. The use of claim 12 wherein the demyelating disease is optic neuritis, multiple sclerosis, allergic encephalomyelitis.

14. A pharmaceutical composition comprising AV-Cat, rAAV-Cat and rAAV-MnSOD.

15. A pharmaceutical composition comprising AV-Cat and rAAV-MnSOD.

16. A kit for treating demyelinating disease in a human comprising, (i) an rAAV composition that comprises a selected polynucleotide sequence encoding a mammalian catalase or superoxide dismutase polypeptide; (ii) a device adapted for delivering an rAAV composition to said animal; and (iii) instructions for using said kit.

17. The kit of claim 15 further comprising an AV composition comprising a polynucleotide sequence encoding catalase.

18. The kit of claim 16 wherein the superoxide dismutase is MnSOD.

19. Use of a composition comprising rAAV -MnSOD and AV-Cat to prepare a medicament to reduce the effects of demyelating disease in a mammal.

20. A pharmaceutical composition comprising rAAV-SOD vectors that comprise at least two cell specific promoter genes in separate or same vectors selected from the group consisting of CMV, PDGF and VEGF and optionally including a reporter gene.

21. The composition of claim 20 wherein the SOD is MnSOD.

22. The composition of claim 20 further comprising a rAAV-Cat vector that includes at least two cell specific promoter genes in a single vector or separately in a plurality of vectors, the promoter selected from the group consisting of CMV, VEGF and PDGF promoter genes.

23. Use of the composition of any of claims 20-22 to prepare a medicament to reduce the effects of a demyelinating disease in a mammal.