Dynamin inhibitors from different manufacturers have similar effects on HIV-1 uptake and fusion with endosomes. HXB2 pseudoviruses were bound to TZM-bl or CEMss cells at 4°C (see Methods), and fusion was initiated by shifting to 37°C for 90 min (in DMEM) and measured by the BlaM assay. (A) Fusion with TZM-bl cells (black bars) in the presence or absence of 80 μM dynasore or dynole 34-2 in DMEM. Dynasore from Ascent was used at 100 μM. The effects of DMSO (0.1% v/v) and 80 μM dynasore (Santa Cruz) on fusion with CEMss cells are also shown (open bars). The extent of fusion in the presence of 1 μM C52L is shown for comparison. (B) Inhibition of HXB2 pseudovirus fusion with primary CD4+ T cells by 80 μM dynasore (Santa Cruz) and 1 μM C52L (filled bars). The effect of DMSO, dynasore and C52L on cell viability, as determined by the MTS assay, is shown by open bars. (C-E) The kinetics of HXB2 escape from C52L, dynasore and the temperature block (TB) applied at indicated times of incubation at 37°C. The background fusion (~15% of the maximal signal) in the presence of dynasore was subtracted from the dynasore kinetics data to ease the comparison with the C52L and TB kinetics. Data points are means and SEM of combined triplicate measurements from three independent experiments.