Prevalence of Neutralizing Antibodies Against AAV Serotypes 2 and 9 in Healthy Participants from Multiple Centers Across China and Patients with DMD/BMD.

To facilitate adeno-associated virus (AAV)-mediated gene therapy in China, we conducted a study on the distribution of AAV-neutralizing antibodies (NAbs) in healthy subjects and in patients with Duchenne muscular dystrophy (DMD)/Becker muscular dystrophy (BMD). A total of 352 healthy adult controls (ACs) from a national multicenter study, 100 schoolchild controls (SCs), and 281 patients with DMD/BMD from Peking Union Medical College Hospital were enrolled in this study. Cell-based inhibition assays were applied, and serum samples demonstrating 50% inhibition of infection were considered positive. The seroprevalence of AAV2 and AAV9 NAbs among the 733 participants was 86.1% and 56.3%, respectively. The AAV2 NAbs and AAV9 NAbs positivity rates in the AC, SC, and DMD/BMD groups were 97.4%/86.6%, 100.0%/17.0%, and 66.9%/32.4%, respectively. The seroprevalence of AAV NAbs gradually increased with age, especially in AAV9 NAbs. Females tended to have higher positivity rate than males. Over 85% of ACs had overlapping AAV9 and AAV2 infection. However, being positive for only AAV2 NAbs in the SC group was common, and 30.6% of patients with DMD/BMD were negative for both AAV2 and AAV9 NAbs. Our findings reveal that a significant proportion of patients with DMD/BMD were negative for AAV2 and AAV9 NAbs, which is the population that is most amenable to being treated with gene therapy.