AAV gene therapy

Adeno-associated virus (AAV) gene therapy uses recombinant AAV capsids to deliver a transgene cassette — typically a promoter, coding sequence, and poly-A signal — to target tissues. Different serotypes (AAV9 for CNS/muscle, AAV8 for liver, AAV2 for retina) have distinct tissue tropisms determined by capsid-surface receptor interactions, and the ~4.7 kb packaging limit constrains which genes can be delivered as a single construct. Pre-existing NAb titres and T-cell responses to capsid proteins are the principal immunogenicity barriers, and in some trials have required plasmapheresis or high-dose immunosuppression to avoid clearance or hepatotoxicity. In longevity-relevant preclinical work, AAV vectors have been used to deliver Klotho, TERT, follistatin, and FGF21 transgenes in rodents, yielding functional improvements; no anti-aging AAV product has received regulatory approval, and all human longevity applications remain investigational or compassionate-use.