FIG. 1.

Autologous Nab activity and B-cell proliferation during experimental infection of SMs. (A) Neutralization activity levels in plasma from five SMs (filled black circles), which were experimentally inoculated with plasma from a naturally SIV-infected SM, and four HIV-1-infected Zambian subjects (half-filled squares), who were recently infected through heterosexual contact, are shown. The horizontal bars represent the median for each group. To assess neutralizing activity, pseudoviruses were created by expressing each cloned Env with an HIV-1 env-deficient backbone (ΔSG3). JC53-BL (Tzm-bl) cells were infected with each pseudovirus in the presence or absence of serially diluted autologous plasma. Each point represents the average level of neutralization at a 1:100 dilution of plasma for at least two Env clones (see Table 1 for number of Envs tested). Each neutralization assay was performed twice independently, using duplicate wells. Statistical significance between the groups was determined by a Mann-Whitney test, using GraphPad Prism 5. Longitudinal measurements of endpoint antibody ELISA titers in plasma (filled green circles) (23) (B), autologous neutralization activity in plasma (filled blue diamonds) (C), percentages of Ki-67⁺ CD20⁺ cells in blood (filled black triangles) (D), and percentages of CD20⁺ cells in blood (filled red squares) (E) are shown for the five experimentally inoculated SMs combined. In panel C, each point represents average neutralization at a 1:100 dilution of plasma over time for at least two day 14 Env clones from each SM. For panels D and E, PBMCs were gated by forward and side scatter, and the CD3⁻ CD20⁺ population was assessed for Ki-67 staining (D) by flow cytometry. SP34-2 was used to stain CD3, L27 was used for CD20, and B56 was used for Ki-67 (all from BD Biosciences). Error bars represent the standard errors of the means (SEMs). Plasma viral load peaked at day 14 (data not shown). Filled symbols in panels A through E indicate data generated from experimentally infected SMs.