HIV-1 therapy with monoclonal antibody 3BNC117 elicits host immune responses against HIV-1

Abstract

3BNC117 is a broad and potent neutralizing antibody to HIV-1 that targets the CD4 binding site on the viral envelope spike. When administered passively, this antibody can prevent infection in animal models and suppress viremia in HIV-1-infected individuals. Here we report that HIV-1 immunotherapy with a single injection of 3BNC117 affects host antibody responses in viremic individuals. In comparison to untreated controls that showed little change in their neutralizing activity over a 6-month period, 3BNC117 infusion significantly improved neutralizing responses to heterologous tier 2 viruses in nearly all study participants. We conclude that 3BNC117-mediated immunotherapy enhances host humoral immunity to HIV-1.

Trial registration: ClinicalTrials.gov NCT02018510.

Figure 1. Virus sensitivity to 3BNC117 and autologous antibody responses

A. Graph displays kinetics of 3BNC117 antibody decay in HIV-1-infected individuals as determined by a validated anti-idiotype ELISA (16). Shown are mean values of patients infused in each respective dose group. Each patient sample was measured in duplicates. Gray shaded area indicates lower level of accuracy of the assay (2 µg/ml). Red arrows indicate the timepoints of IgG purification. B. Autologous virus sensitivity to 3BNC117 before (day 0, grey) and 4 wks (black) after 3BNC117 infusion. Y-axis shows IC₅₀s for 3BNC117 on viral culture supernatants from PBMCs determined by TZM.bl assay. Neutralization assays performed in duplicates. C. Graph shows the AUC of the neutralization curves of purified IgGs obtained from sera on day 0 (orange) or wk 24 (green) against day 0 (left panel) or wk 4 (right panel) autologous viruses. Neutralization assays performed in duplicates. p-values determined by Wilcoxon signed-rank test.

Figure 2. Heterologous antibody responses

A. Graph shows the difference in overall AUC (mean AUC change) per individual in TZM.bl assays against 13 heterologous viruses (see 2D) for day 0 vs. wk 24 IgG obtained from 36 untreated viremic controls (mean sampling interval: 26.8 wks), 15 viremic individuals infused with 3BNC117 (mean sampling interval: 24.1 wks), and 12 ART-treated individuals receiving 3BNC117 infusion (mean sampling interval: 24.0 wks) (16). Neutralization assays performed in duplicates. p-values determined by unpaired Wilcoxon test (rank-sum test). B. Graph shows the aggregated differences in AUC between d0 and wk 24 IgG assayed by TZM.bl for all viruses and all individuals. Each dot represents a single AUC difference for a single virus from one individual displayed in A. Colored bars represent mean of all AUCs. Whiskers show standard deviation. p-values determined using generalized estimating equations (38). C. Graph shows 3BNC117 antibody levels (ELISA, white) and TZM.bl neutralization titer (green) against tier 2 strain Q769.d22 in subject 2A3 D. Mean AUCs of IgGs of all individuals at d0 (grey) and wk 24 (color of respective group) for each HIV-1 pseudovirus tested. Changes in neutralization of viremic control individuals without 3BNC117 infusion are shown in yellow (left). Change in neutralization of 3BNC117-treated individuals shown in dark (off ART, middle) and light blue (on ART, right). p-values determined using unpaired Wilcoxon test (rank-sum test). Red stars indicate significant p-values after Bonferroni-correction (threshold p < 0.0038).

Figure 3. HIV-1 quasispecies diversity before and after 3BNC117 infusion

A. Maximum likelihood phylogenetic tree of single genome-derived env gene sequences from d0 plasma, before therapy with 3BNC117 (Table S9). Asterisks indicate bootstrap values of 100%. Individual viral sequences are color coded as indicated. B. Scatter plots depicting pairwise nucleotide sequence diversity of plasma env sequences on d0, and wk 4 (2E5, wk 6), 12 and 24 after infusion. Each dot represents the pairwise genetic difference between two sequences at a given timepoint. Colored bars indicate median diversity, while black bars indicates the interquartile range. p-values were determined using a two-sample U-statistic based Z-test (–41). C. Graph shows the relationship between d0 mean heterologous neutralizing AUC against a panel of tier 1 (n=1) and tier 2 (n=12) viruses (x-axis) and the median pairwise nucleotide diversity for each patient (y-axis).

Figure 4. Antibody responses to the evolving viral quasispecies

A. Maximum-likelihood phylogenetic trees of single genome-derived env gene sequences from subjects 2A1 and 2E1 sampled on d0 and wk 4, 12, and 24 after 3BNC117 infusion (left). Clades with bootstrap support ≥ 70% are indicated by a black star and are arbitrarily named groups A-D in case of subject 2A1. Bar graphs (middle) indicate the timepoints from which sequences in the tree are derived. Heat maps (right) show the 3BNC117 IC₅₀, d0 IgG IC₅₀ and wk 24 IgG IC₅₀ values against autologous pseudoviruses using env sequences as indicated by colored stars. Neutralization assays performed in duplicates. B. Sequence logo plots illustrating longitudinal amino acid changes in and around known 3BNC117-contact residues (26, 27) in subject 2A1 and 2E1. Letters indicate deviations from the d0 consensus shown at the top, whereas white spaces indicate agreement with the d0 consensus. Colors indicate basic (dark blue) and acidic (red) residues and a turquoise “O” is used instead of “N” to indicate a potential N-glycosylation site. Logo plots were generated using LASSIE (28). + symbols indicate 3BNC117 contact residues confirmed by two crystal structures (26, 27).