AAV retinal transduction in a large animal model species: comparison of a self-complementary XXXX /5 with a single-stranded @entity4700 /5 vector.

@entity4700 @entity1573 @entity19 @entity235
PURPOSE: To compare self-complementary (sc) and single-stranded (ss) adeno-associated viral 2/5 ( @entity4700 /5) vectors for retinal cell transduction in the @entity235 when delivered by subretinal injection. METHODS: ScAAV2/5 and ssAAV2/5 vectors encoding enhanced green fluorescent protein (GFP) under control of the @entity1573 beta actin promoter were prepared to the same titer. Equal amounts of viral particles were delivered into the subretinal spaces of both eyes of two @entity235 . In each @entity235 , one eye received the scAAV2/5 and the other the ssAAV2/5. In vivo expression of GFP was monitored ophthalmoscopically. The @entity235 were sacrificed, and their retinas were examined by fluorescent microscopy and immunohistochemistry to determine GFP expression patterns and to assay for glial reactivity. RESULTS: GFP expression in the scAAV2/5 injected eyes was detectable at a much earlier time point than in the ssAAV2/5 injected eyes. Expression of GFP was also at higher levels in the scAAV2/5-injected eyes. Expression levels remained stable for the seven month duration of the study. The types of cells transduced by both vectors were similar; there was strong reporter gene expression in the RPE and photoreceptors, although not all cones in the transduced area expressed GFP. Some horizontal and M  ller cells were also transduced. CONCLUSIONS: When delivered by subretinal injection in the @entity235 , scAAV2/5 induces faster and stronger transgene expression than ssAAV2/5. The spectrum of retinal neurons transduced is similar between the two vectors. These results confirm in a large animal model those previously reported in the @entity19 . ScAAV2/5 shows promise for use in the treatment of conditions where a rapid transgene expression is desirable. Furthermore, it may be possible to use a lower number of viral particles to achieve the same effect compared with ssAAV2/5 vectors.
