Abstract
Purpose :
Adeno-associated viruses (AAVs) are the viral vectors of choice for ophthalmological gene therapy research as they have been proven to be efficient for long-term gene expression in retinal cells. However, AAV-mediated retinal cell transduction efficiency is limited due to the specificity of cell surface receptor requirement for transduction by the various viral serotypes. Advances in AAV capsid optimization to improve cell tropism have led to the engineering of synthetic hybrid AAV capsid vectors that mediate widespread transgene expression in retinal cells. However, these novel candidates have not been compared side by side. To identify AAV serotypes that mediate efficient retinal transduction and gene expression to rescue inherited retinal degenerative diseases, we compared the efficiency of retinal cell transduction of four novel AAV serotypes in adult WT mice after intraocular delivery
Methods :
Four different AAV-CMV-GFP hybrid serotypes were tested in vivo in 2-month-old WT mice. 1.0 ul of 1x10^12 GC/ml of each viral particle was delivered into mouse eyes either by intravitreal or subretinal injection. At 1-month and 3-month post injections, the tropism of each serotype to efficiently transduce retinal cells was examined using GFP transgene expression in photoreceptor (PR) and RPE cells by fundoscopy, fluorescence microscopy, and histology
Results :
Fundoscopy and immunohistological analysis of GFP levels in the retina showed that mice injected with AAVDJ and AAVDJ8 had the highest GFP fluorescence. Subretinal injection resulted in all serotypes successfully transducing PR and RPE cells with AAVDJ8 and AAVDJ exhibiting the highest transduction and GPF expression efficiency. With intravitreal injection, AAV2-7m8 and AAVDJ serotypes led to efficient PR transduction, while AAVDJ8 exhibited the highest RPE transduction. Visual function showed no differences between all the serotypes injected
Conclusions :
We found that novel synthetic AAV serotypes differentially transduce both the inner and outer retinal cell layers depending on the method of intraocular delivery. Of the four serotypes studied, AAVDJ8 seems to be the most effective at transducing both PR and RPE cells when injected intravitreally. Because intravitreal injection is less invasive and is often utilized on human subjects, novel AAV capsids capable of successfully transducing PR and RPE cells by intravitreal delivery would transform the retinal gene therapy landscape
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.