Abstract
Adeno-associated viral vectors (AAV) have been shown to be safe in the treatment of retinal degenerations in clinical trials. Thus, improving the efficiency of viral gene delivery has become increasingly important to increase the success of clinical trials. In this study, structural domains of different rAAV serotypes isolated from primate brain were combined to create novel hybrid recombinant AAV serotypes, rAAV2/rec2 and rAAV2/rec3. The efficacy of these novel serotypes were assessed in wild type mice and in two models of retinal degeneration (the Abca4−/− mouse which is a model for Stargardt disease and in the Pde6brd1/rd1 mouse) in vivo, in primate tissue ex-vivo, and in the human-derived SH-SY5Y cell line, using an identical AAV2 expression cassette. We show that these novel hybrid serotypes can transduce retinal tissue in mice and primates efficiently, although no more than AAV2/2 and rAAV2/5 serotypes. Transduction efficiency appeared lower in the Abca4−/− mouse compared to wild type with all vectors tested, suggesting an effect of specific retinal diseases on the efficiency of gene delivery. Shuffling of AAV capsid domains may have clinical applications for patients who develop T-cell immune responses following AAV gene therapy, as specific peptide antigen sequences could be substituted using this technique prior to vector re-treatments.
Highlights
Inherited retinal dystrophies such as retinitis pigmentosa (RP) have until recently been untreatable
An interaction was detected between strain and rAAV serotype (p = 0.013), suggesting differing effects of the rAAV serotypes depending on retinal pathology
Post hoc analysis showed that retinal green fluorescent protein (GFP) expression after viral transduction was lower in Pde6brd1/rd1 mice than in wild type (WT) controls (p = 0.02), and lowest in the Abca42/2 mice (p,0.001 when compared to both other strains)
Summary
Inherited retinal dystrophies such as retinitis pigmentosa (RP) have until recently been untreatable. While current retinal gene therapy trials have shown AAV vectors to be safe, there remain ongoing efforts to improve efficiency of gene delivery and to restrict vector tropism to specific retinal cell populations by modifying the capsid protein and/or the expression cassette. In the former case it has recently been shown that recombinant packaging of the AAV2 expression cassette into an AAV8 capsid (rAAV2/8) significantly enhanced transduction of primate photoreceptors when assessed by expression of green fluorescent protein (GFP) [8]. The AAV5 capsid is known to transduce primate foveal cones effectively, as evidenced by restoration of trichromatic color vision in the macaque following treatment of dichromats with rAAV2/5 vector encoding the long (L) opsin gene [9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
