Three families of CD4-induced antibodies are associated with the capacity of plasma from people living with HIV to mediate ADCC in the presence of CD4-mimetics.

Unlabelled: CD4-mimetics (CD4mcs) are small molecule compounds that mimic the interaction of the CD4 receptor with HIV-1 envelope glycoproteins (Env). Env from primary viruses normally samples a "closed" conformation that occludes epitopes recognized by CD4-induced (CD4i) non-neutralizing antibodies (nnAbs). CD4mcs induce conformational changes on Env resulting in the exposure of these otherwise inaccessible epitopes. Here, we evaluated the capacity of plasma from a cohort of 50 people living with HIV to recognize HIV-1-infected cells and eliminate them by antibody-dependent cellular cytotoxicity (ADCC) in the presence of a potent indoline CD4mc. We observed a marked heterogeneity among plasma samples. By measuring the levels of different families of CD4i Abs, we found that the levels of anti-cluster A, anti-coreceptor binding site, and anti-gp41 cluster I antibodies are responsible for plasma-mediated ADCC in the presence of CD4mc.

Importance: There are several reasons that make it difficult to target the HIV reservoir. One of them is the capacity of infected cells to prevent the recognition of HIV-1 envelope glycoproteins (Env) by commonly elicited antibodies in people living with HIV. Small CD4-mimetic compounds expose otherwise occluded Env epitopes, thus enabling their recognition by non-neutralizing antibodies (nnAbs). A better understanding of the contribution of these antibodies to eliminate infected cells in the presence of CD4mc could lead to the development of therapeutic cure strategies.