Enhancement versus neutralization by SARS-CoV-2 antibodies from a convalescent donor associates with distinct epitopes on the RBD

Several potent neutralizing antibodies against SARS-CoV-2 virus have been identified. However, antibody-dependent enhancement (ADE) has not been comprehensively studied for SARS-CoV-2, and the relationship between enhancing versus neutralizing activities and antibody epitopes remains unknown. Here, we select a convalescent individual with potent IgG neutralizing activity and characterize his antibody response. Monoclonal antibodies isolated from memory B cells target four groups of five non-overlapping receptor-binding domain (RBD) epitopes. Antibodies to one group of these RBD epitopes mediate ADE of entry in Raji cells via an Fcγ receptor-dependent mechanism. In contrast, antibodies targeting two other distinct epitope groups neutralize SARS-CoV-2 without ADE, while antibodies against the fourth epitope group are poorly neutralizing. One antibody, XG014, potently cross-neutralizes SARS-CoV-2 variants as well as SARS-CoV-1 with respective IC50 values as low as 5.1 ng/ml and 23.7 ng/ml, while not exhibiting ADE. Therefore, neutralization and ADE of human SARS-CoV-2 antibodies correlate with non-overlapping RBD epitopes.