Stability of the adeno-associated virus 8 reference standard material

Adeno-associated virus (AAV) vectors are extensively used for gene therapy clinical trials. Accurate and standardized titration methods are essential for characterizing and dosing AAV-based drugs and thus to assess their safety and efficacy. To this end, the Reference Standard Materials (RSM) working group generated standards for AAV serotype 2 and serotype 8. The AAV8RSM (ATCC® VR-1816™) was deposited to the American Type Culture Collection in 2014 and is available to the scientific community. Here, three independent laboratories of the RSM working group provide stability data of the AAV8RSM 2 years after the initial characterization and after container relabeling performed at the ATCC. The AAV8RSM showed constant titers across experimental conditions: 1.48 ± 0.62 × 10¹² vector genome (vg)/ml, 9.38 ± 11.4 × 10⁸ infectious units (IU)/ml and 5.76 ± 2.39 × 10¹¹ total particles (p)/ml as determined by qPCR, TCID₅₀ and ELISA, respectively. Additionally, the AAV8RSM capsid protein integrity assessed by SDS-PAGE was equivalent to the original analyses. In conclusion, the AAV8RSM titers remained stable for two years under appropriate storage conditions ( <-70° C). The use of RSM is strongly recommended and endorsed by regulatory agencies to normalize laboratory internal controls and to provide accurate titration of AAV vectors lots.