HIV-1 Specific Antibody Titers and Neutralization among Chronically Infected Patients on Long-Term Suppressive Antiretroviral Therapy (ART): A Cross-Sectional Study

The majority of potent and broadly neutralizing antibodies against HIV-1 have been isolated from untreated patients with acute or chronic infection. To assess the extent of HIV-1 specific antibody response and neutralization after many years of virologic suppression from potent combination ART, we examined antibody binding titers and neutralization of 51 patients with chronic HIV-1 infection on suppressive ART for at least three years. In this cross-sectional analysis, we found high antibody titers against gp120, gp41, and the membrane proximal external region (MPER) in 59%, 43%, and 27 % of patients, respectively. We observed significantly higher endpoint binding titers for gp120 and gp41 for patients with.10 compared to #10 years of detectable HIV RNA. Additionally, we observed higher median gp120 and gp41 antibody titers in patients with HIV RNA,50 copies/mL for #5 years. 22 % of patients neutralized a HIV-1 primary isolate (HIV-1JR-FL) and 8% neutralized a HIV-2/HIV-1 MPER chimera. Significantly greater HIV-1JR-FL neutralization was found among patients with.10 years of detectable HIV RNA (8/20 [40.0%] versus 3/31 [9.7%] for #10 years, p = 0.02) and a trend toward greater neutralization in patients with #5 years of HIV RNA,50 copies/mL (7/20 [35.0%] versus 4/31 [12.9%] for.5 years, p = 0.08). All patients with neutralizing activity mediated successful phagocytosis of VLPs by THP-1 cells after antibody opsonization. Our findings of highly specific antibodies to several structural epitopes of HIV-1 with antibody effector functions an