AAV9 Targets Cone Photoreceptors in the Nonhuman Primate Retina

Abstract

Transduction of retinal pigment epithelial cells with an adeno-associated viral vector (AAV) based on serotype 2 has partially corrected retinal blindness in Leber congenital amaurosis type 2. However, many applications of gene therapy for retinal blindness rely on the efficient transduction of rod and cone photoreceptor which is difficult to achieve with first generation vector technology. To address this translational need, we evaluated rod and cone photoreceptor targeting of 4 novel AAV capsids (AAV7, AAV9, rh.64R1 and rh.8R) versus AAV2 and AAV8 in a foveated retina. Eyes of 20 nonhuman primates were injected subretinally in the proximity of the fovea. While numerous vectors efficiently transduced rods, only AAV9 targeted cones both centrally and peripherally efficiently at low doses, likely due to the abundance of galactosylated glycans, the primary receptor for AAV9, on cone photoreceptors. We conclude AAV9 is an ideal candidate for strategies that require restoration of cone photoreceptor function.

Noninvasive gene delivery to foveal cones for vision restoration

“…However, for achromatopsia patients, as well as the subset of retinitis pigmentosa patients with strong neutralizing antibody titers against AAV2 (33), a subretinal approach might be advantageous. Previous studies have shown that subretinal injection of AAV9 leads to efficient transgene expression in cones both centrally and peripherally at low doses, likely due to the abundance of galactosylated glycans, the primary receptor for AAV9, on cone photoreceptors (30,35). Based on this, we reasoned that an enhanced AAV9 variant might afford efficient transduction of foveal cones from a distal bleb.…”

“…We and others have shown transduction of macaque cones using AAV variants with ubiquitous promoters (16,(29)(30)(31)(32), but achieving cone transduction by vitreally administered AAV has only been possible at high doses, leading to inflammation (16,29). We reasoned that foveal cone targeting could be achieved if we use a strong cone-specific promoter at lower intravitreally injected AAV doses compatible with safety (29,33).…”

Impact of Heparan Sulfate Binding on Transduction of Retina by Recombinant Adeno-Associated Virus Vectors

“…However, the majority of inherited retinal diseases are caused by defects in photoreceptors, highlighting the need to identify serotypes capable of transducing this cell type. We and others have shown that various subretinally delivered AAV serotypes are capable of efficient transduction of photoreceptors in nonhuman primates (NHP) (14)(15)(16)(17)(18)(19). However, subretinal injection of AAV2 under the fovea of some LCA2 patients led to central retinal thinning and loss of visual acuity (20).…”

Leber Congenital Amaurosis Caused by Mutations in GUCY2D

“…Keeping in mind that the primary target in LCA1 is the central, cone-rich retina, focus must be placed on each serotype's ability to transduce cone photoreceptors. Only partial cone transduction was achieved following subretinal delivery of elevated doses of AAV8-CMV-GFP (10 11 vg delivered) in nonhuman primates (Vandenberghe et al 2011(Vandenberghe et al , 2013. At a lower dose (10 10 vg delivered), this serotype failed to transduce foveal, parafoveal, or perifoveal cones (Vandenberghe et al 2011).…”