Modification of the VP1u region boosts transduction of adeno-associated virus vectors for ocular gene therapy

Adeno-associated virus (AAV) capsids that can confer efficient and safe gene therapy of the retina remain unmet needs. In this study, we isolated a library of natural capsids from human tissues and identified two variants that conferred strong transduction of retinal tissues following intravitreal injections into mice and non-human primates. Interestingly, the defining amino acids among the two variants are located within the luminal VP1 unique (VP1u) region of the capsid. Combining these defining residues into a single capsid (AAV2.MC1) had an additive effect. We demonstrated that the MC1 modification enhances intracellular trafficking and nuclear entry. Importantly, we provide proof of concept that the AAV2.MC1 capsid can deliver an anti-vascular endothelial growth factor (VEGF) transgene to treat wet age-related macular degeneration. Finally, we demonstrate that the modification can also be grafted onto other AAV serotypes to boost baseline transduction. These findings open up new avenues for capsid modification through targeted alterations of the VP1u region.