ATP synthase inhibitors prevent APC-mediated HIV-1 transfer at the cell-cell interaction step. (A) The ATP synthase inhibitor, citreoviridin, was added to the transfer assay with DCs at the indicated concentrations either at step 1 (diamonds) or at step 4 (triangles) of the assay as described in “Measuring transfer of HIV-1 to target cells by APCs.” “Infectivity” represents the direct effect of the inhibitor on the infectivity of the virus as measured directly on TZM cells. The infectivity in the absence of citreoviridin was determined as 100%. (B) Dose-dependent inhibition of APC-mediated HIV-1 transfer by recombinant IF1 at different pH. Viral transfer was mediated by DC-Raji cells, and 25 μg (8.3 × 10−5M) of the endogenous inhibitor IF1 was added at the step of APC-target cell interaction. (C) Effect of different inhibitors on DC-mediated HIV-1 transfer at the step of APC-target cell interaction. Control indicates no inhibitors. The amount of protein used per assay was 10 μg (1.3 × 10−7M) for each antibody and 25 μg (8.3 × 10−5) for IF1. Experiments were repeated at least 3 times and were performed in triplicates. Bars represent the SEM of the individual samples in a group.
