Figure 6

Characteristics of MVC-Sens and MVC-Res fusion with CD4⁺ T cells. a Fusion kinetics of BlaM-vpr-containing MVC-Sens and MVC-Res viruses with activated CD4⁺ T-lymphocytes are shown, in the presence or in the absence of 10 μM MVC. After virus spinoculation onto cells at 4°C and cell washing, fusions were run for the indicated times at 37°C and cells were then loaded with CCF2/AM. Results are expressed as the percentage of BlaM-vpr positive cells, i.e. cells displaying cleaved CCF2/AM fluorescence (at 447 nm). Results are mean ± SEM of two independent determinations out of at least five. b Levels of fusion at 2 h. for the viruses MVC-Sens, MVC-Res and their related variants Sens(+A), Sens(V3R), Res(−A) and Res(V3S), in the absence or in the presence of 10 μM MVC. Results, expressed as fold changes compared to the extent of fusion of MVC-Sens, represent mean ± SEM of 2–10 independent determinations. c The panel represents data from the fusion kinetics of MVC-Sens and MVC-Res w/or w/o 10 μM MVC that were normalized to the maximal extent of fusion at 300 min. d and e Time-of-inhibitor-addition experiments revealing that MVC-Res interacts with CD4 and CCR5 receptors more slowly than MVC-Sens. Fusion of viruses with CD4⁺ T cells was measured at 240 min under conditions where 50 μg/ml of the anti-CD4 mAb Q4120 (d) or 20 μg/ml of the anti-CCR5 mAb 2D7 (e) was added at the indicated time points after cell transfer to 37°C (time zero), in the presence or in the absence of 10 μM MVC. Results are expressed as the percentage of fusion relative to fusion in the absence of inhibitor (time 240 min). Representative experiments out of three independent experiments are shown.