Manhas, S.; Brooker, J. P.; Shetler, C.; Penrose, K. J.; Jaiswal, D. S.; Chu, X.; Li, W.; Kearney, M. F.; Mellors, J. W.; Halvas, E. K.

Despite adherence to antiretroviral therapy (ART), low levels of plasma virus persist in most individuals with HIV-1. In a small subset of these individuals, this non-suppressible viremia is detected by routine clinical testing (plasma HIV-1 RNA >20 copies/ml) and has been shown to be of clonal cellular origin. The mechanisms by which these virions escape immune clearance is not defined, but reduced binding and neutralization of their surface envelope protein (Env) by antibodies (Abs) may contribute. To assess this possibility, we measured the monoclonal antibody (mAb) sensitivity of HIV-1 Env in plasma virus from 4 well-characterized individuals on ART with non-suppressible viremia. Thirty-two env plasma sequences were used to produce pseudovirus for neutralization assays with both autologous plasma and a panel of 15 recombinant antibodies that targeted different regions of HIV-1 Env protein. We found that autologous plasma had no neutralizing activity against the pseudoviruses consistent with persistence of viremia. In general, the Envs from the non-suppressible plasma virus were also less sensitive to mAb neutralization compared controls: tier 1 (6535), tier 2 (TRO11) or tier 3 (PVO) subtype B envs, although variability across Envs was evident. Two Env protein variants from one donor, R-09_A8 and R-09_C2, were less sensitive to VRC01 likely due to an additional N-glycan site at a VRC01 contact site and longer V5 regions. Most of the donor Envs were sensitive to at least two of three V3-glycan mAbs except for variant C-03_A6, which showed reduced sensitivity to all three. The CD4 binding site mAb 3BNC117 and the Gp41-specific mAb 10E8 neutralized pseudoviruses from all donors, indicating the potential for clearance of persistent viremia in these individuals studied.