Controllable gene delivery via masked adeno-associated viral vectors.

Controllable gene delivery to specific tissue by adeno-associated viruses (AAVs) is a challenge in gene therapy. Here we develop masked AAVs, whose transduction is blocked and restored only on pathological activation or by activation triggered by exogenous signals. The masking effect is accomplished by genetic encoding of non-canonical amino acid with tetrazine groups into AAV capsid proteins, allowing efficient reaction with trans-cyclooctene-modified truncated AAV receptor or polyethylene glycol to completely block viral infectivity in mice. With three different cleavable linkers, masking groups are selectively removable through liver-specific protease matriptase-2, near-infrared light or inflammation-associated reactive oxygen species, thus restoring the infectivity of AAVs and allowing localized transduction in mice. Systemic administration of protease-activated masked AAVs enables tissue-specific gene delivery to the liver, while administration of near-infrared-activated masked AAVs provides localized transduction in irradiated regions such as muscles and brain. Intravenous administration of reactive-oxygen-species-activated AAVs achieves targeted gene delivery to the myocardium in a cardiac ischaemia-reperfusion injury model, resulting in the localized expression of VEGF-A165 and myocardial repair.