FIG 6.
Synergy between Env-destabilizing treatments enhances virus sensitivity to neutralization. (A) Enhancement of antibody neutralization by cold, urea, and their combination. Viruses containing 89.6(225I, 305E) Env were treated for 8 h with all possible combinations of cold, urea, or the indicated inhibitors (Venn diagram) and then added to cells to measure residual infectivity. The fold inactivation induced by each treatment and the calculated synergistic effects were determined as described in equation 1 and equation 2 and are expressed as their log10 values. The color coding of each section of the bars corresponds to that of the treatment combination shown in the Venn diagram. (B and C) Effects of urea, JRC-II-191, and their combination on HIV-1 neutralization. Viruses containing 89.6 Env were incubated with cells in the absence or presence of urea, JRC-II-191 (4 μM), and the indicated inhibitors for 6 h. The cells were then washed and further cultured to measure infectivity. Calculations were performed as described for panel A. (D) Effects of urea on antibody-mediated neutralization of different Envs. Viruses containing the indicated Envs were incubated with urea, JRC-II-191 (4 μM), and inhibitor (either MAb 17b or PS). The fold reduction in infection relative to samples similarly treated but without urea is shown (i.e., EU,I,J/EI,J). (E) Synergistic effects between urea and JRC-II-191. Synergy between treatments was calculated as described in equation 1. The data represent averages of at least two independent experiments. (F) Urea-mediated enhancement of antibody neutralization increases with the JRC-II-191 concentration. Viruses containing 89.6(225I, 305E) were added to cells in the presence of urea, MAb 17b, or PS and different concentrations of JRC-II-191 as described for panel B. The data represent fold changes in infectivity relative to untreated samples. The error bars indicate SEM.