Phenotypic analysis of HIV-1 resistance to CD4 binding site broadly-neutralizing antibodies

Abstract Broadly neutralizing antibodies (bNAbs) show strong immunotherapy potential by targeting conserved regions of the HIV-1 envelope. Single bNAb use in viremic individuals quickly results in the emergence of escape variants, likely originating from existing quasispecies. An ex vivo assay was developed to predict bNAb efficacy in viremic individuals. The development of a predictive bNAb efficacy model may assist with the planning of future clinical trials. The ex vivoassay used pre-infusion CD4 +T cells from participants enrolled in the VRC 607/ACTG A5378 phase I study of the CD4 binding site (CD4bs) bNAbs’ VRC01LS (n=7) or VRC07-523LS (n=9). From these assays, the escape variant signatures of outgrowth viruses that replicated in presence of CD4bs bNAbs, were identified. We found that these escape variants contained key changes to the ß23-V5 region of the gp120 envelope, including charge changes, glycan loss, and/or glycan shifts. Outgrowth viruses from each participant had similar escape mutation patterns. Resistance mutations of the viral env sequences were confirmed in pseudovirus-based neutralization assays. We found complementary escape profiles from 3 CD4bs bNAbs (1–18LS, N6LS, and VRC01v23) with ex vivoand neutralization assays showing suppression by 1 or 2 but not all 3 bNAbs, supporting the potential for combination bNAb therapy. Our data suggest that the simultaneous use of multiple CD4 binding site bNAbs together could aid in limiting viral escape. Supported by intramural funds from NIH.