High-Resolution Structural Characterization of a New Adeno-associated Virus Serotype 5 Antibody Epitope toward Engineering Antibody-Resistant Recombinant Gene Delivery Vectors

Abstract

Biologics based on recombinant AAVs (rAAVs) are increasingly becoming attractive human gene delivery vehicles, especially after the approval of Glybera in Europe and Luxturna in the United States. However, preexisting neutralizing antibodies against the AAV capsids in a large percentage of the human population limit wide-spread utilization of these vectors. To circumvent this problem, stealth vectors must be generated that are undetectable by these antibodies. This study details the high-resolution characterization of a new antigenic region on AAV5, a vector being developed for numerous delivery applications. The structure of AAV5 complexed with HL2476, a novel antibody, was determined by cryo-EM to 3.1-Å resolution. The resolution of the density map enabled the identification of interacting residues between capsid and antibody and the determinants of neutralization. Thus, the information obtained from this study can facilitate the generation of host immune escape vectors.