Adeno-Associated Vector (AAV) Information : Adeno-associated viruses (AAVs) are nonenveloped viruses that package a linear, single-stranded DNA (ssDNA) genome of approximately 4.7 kb. Their lack of pathogenicity, their low capacity to induce cellular immune response, their ability to infect both dividing and nondividing cells, as well as their long-term gene expression, have made them valuable tools for in vitro and in vivo gene delivery.