Cone And Rod Transduction With Alternative AAV Serotypes In The Macula Of Non-human Primates

Abstract

Purpose: : The evaluation of vector transduction characteristics of adeno-associated virus (AAV) serotypes in the mouse and non-human primate (NHP) retina following a subretinal injection with as goal to establish a preclinical dataset of 6 AAV capsid types that will help to identify vectors for clinical translation with the superior targeting for RPE, rods and/or cones across the retina, macula and fovea.

Methods: : A group of 27 AAVs identified through mining of biological diversity and capsid engineering were selected to represent known structural diversity across AAV clades. These vectors were subretinally injected in C57Bl/6 mice (n=5) at a dose of 3x10E9 genome containing particles (GC) of CMV driven eGFP vector per eye. Cynomolgus macaques eye (n=5/group) were injected subretinally with 10E9 and 10E10 GC carrying CMV.eGFP. Mice and monkeys were followed clinically and experimentally by fundoscopy and ultimately evaluated by histology. Optic nerve and macular eGFP fluorescence was assessed quantitatively and qualitatively.

Results: : Mice and monkeys tolerated the vector injection well. Most vectors transduced RPE efficiently in mice. AAV7, AAV8, hu.11, hu.44R3 and rh.8R demonstrated substantial eGFP expression in photoreceptors. Based on vector tropism and efficiency, AAV7, AAV9, rh.8R and rh.64R1 were next evaluated in the non-human primate retina. Although these vectors transduced the RPE equally efficient to AAV8, photoreceptor transduction at 10E9 GC ranged from 20% by AAV8 to <1% for AAV9. Remarkably, at the higher dose of 10E10 GC, ONL transduction between 40 and 80% for all serotypes tested however with stark difference in terms of cone and rod transduction. Whereas all vectors target rods efficiently at this dose, AAV9 and rh64R1 demonstrate dramatic cone transduction in the fovea and macula.

Conclusions: : AAV gene transfer to the RPE and photoreceptors, including cones is feasible at clinically relevant doses and its efficiency is a function of injection, dose, and capsid structure.

Keywords: gene transfer/gene therapy • retina • adenovirus