Infectivity Assessment of Recombinant Adeno-Associated Virus and Wild-Type Adeno-Associated Virus Exposed to Various Diluents and Environmental Conditions

Recombinant adeno-associated virus (rAAV) is a promising gene delivery vehicle that has been approved as a gene therapy drug for some genetic disorders, and is being evaluated in clinical trials. To further promote clinical research under the Food and Drug Administration Investigational New Drug application, the stability of rAAV must be assessed under various conditions. However, there is scant data concerning the stability of a variety of rAAV serotypes. We hypothesized that the difference of capsid structure causes differences in stability. To investigate this hypothesis, rAAV serotypes (rAAV1, rAAV2, rAAV8, and rAAV9) were exposed to diluents and various environmental conditions, including ultraviolet (UV) irradiation, 0.1 M sodium hydroxide (NaOH), 0.06% sodium hypochlorite (NaClO), tap water, and 70% ethanol (EtOH). The changes of the infectivity of the treated samples were assessed by transduction in HeLaRC32 cells as a criterion of stability. The infectivity between recombinant and wild-type AAV (wtAAV2) was also analyzed. The activity of all rAAV serotypes was weakened by UV irradiation and NaOH and NaClO exposure. Treatment for 10 days with tap water or 70% EtOH did not appreciably inactivate rAAV1, rAAV8, and rAAV9, but did affect the activity of rAAV2. Furthermore, the infectivity of rAAV2 did not surpass wtAAV2 infectivity. The results will be important for clinical studies for gene therapy using rAAV.