Isolating Human Monoclonal Antibodies Against Adeno-Associated Virus From Donors With Pre-existing Immunity

Abstract

With the advent of single B-cell cloning technology, we can isolate antibodies against virtually any antigen to study the interaction of a given pathogen with the immune system and develop novel therapeutic strategies. Antibodies directed against the capsid of adeno-associated viruses (AAV) are a significant obstacle to effectively leveraging AAV as a gene-delivery vector in seropositive individuals. In order to design next-generation vectors that can evade neutralization by these antibodies, studies have mapped the epitopes of mouse monoclonal antibodies generated by immunization with AAV. Although these studies provide critical information regarding capsid immunogenicity, they cannot address (1) differences in the antibody repertoire generated in humans following AAV natural infection; or (2) how reactions can vary when generated in response to vector administration. Here, we isolated and evaluated a panel of novel, fully human anti-AAV antibodies by cloning single memory B cells from a seropositive normal donor. We have validated the utility of this approach to study AAV immunology. Our goal is to leverage this knowledge to design novel AAV variants that can effectively transduce target tissues in individuals with AAV-neutralizing antibodies.

Preclinical safety and biodistribution of CRISPR targeting SIV in non-human primates

“…The AAV antibody prevalence is similar in people with and without HIV and is similar to the prevalence in NHPs. AAV9 is one of the serotypes with the lowest frequency of pre-existing antibodies in the human population with ~33.5% of people with an AAV9 nAb titer [ 18 , 19 ]. In our studies, increases in anti-AAV9 neutralizing antibodies were observed in the highest dosing groups (Group 3, 4) at 6 months following EBT-001 administration.…”

A Decade of Progress in Gene Targeted Therapeutic Strategies in Duchenne Muscular Dystrophy: A Systematic Review

“…Several studies have already addressed the former obstacle by minimizing toxicity, while the latter, though interestingly preserved when delivered with a viral vector, posed another challenge with regard to AAV-mediated efficiency. As thoroughly discussed in the results, there are possibilities that viral vector-mediated approaches could be rendered ineffective due to preexisting humoral immunity ( Giles et al, 2020 ). It is complicated since the full extent of such an immune response may not be fully reflected in in vivo studies employing DMD models as noted by Chicoine et al (2014b) .…”

Adeno-associated virus receptor complexes and implications for adeno-associated virus immune neutralization

“…The neutralizing mAb available are all from animal models. Human mAb have been isolated, but all to-date are binding, not neutralizing, and attempts at structural epitope mapping have not yet succeeded (Giles et al, 2020). Notwithstanding that studies of mAb-binding might not be fully representative of polyclonal neutralization mechanisms (Dudek et al, 2020a), this study focuses on the mAb for which epitopes can be mapped structurally.…”