Fig. 4. Antibody concentration predicts the probability of infection following vaginal SHIV_AD8-EO challenge.

Probit regression analysis was used to estimate the per-challenge probability of vaginal SHIV acquisition as a function of imputed 3BNC117 concentrations in plasma among macaques that were administered 3BNC117 singly (a) or 10–1074 concentrations in plasma among animals that received 10–1074 in combination with 3BNC117 (b). The per-challenge probability of infection among untreated control animals was 0.50 and is denoted in blue. Tick marks represent SHIV challenge events that either did (red) or did not (green) result in systemic infection. The solid black or gray line is the model-based prediction; dashed black lines depict 90% pointwise confidence intervals. Model-based estimates of SHIV infection probabilities following a single vaginal SHIV challenge at the indicated plasma concentrations of 3BNC117 (c) or 10–1074 (d).