FIG. 3.

Effect of TMPRSS2 on HIV-SARS S entry into drug-treated cells. 293T cells were cotransfected (1 μg per 10⁶ cells) with ACE2 plus the empty vector (white bars) or with ACE2 plus TMPRSS2 (hatched bars). One day later, and 1 h prior to transduction with HIV-SARS S pseudoviruses, cells were incubated with bafilomycin A1 (300 nM) or NH₄Cl (25 mM). Vehicle controls were DMSO and water for bafilomycin A1 and NH₄Cl, respectively. HIV-SARS S particles were then concentrated onto cells by a 2-h spinoculation. Bafilomycin and NH₄Cl remained on cells during and after spinoculation, until 6 h posttransduction, at which time cells were rinsed and replenished with fresh medium. Luciferase accumulations were determined at 28 h posttransduction. Error bars represent standard deviations (n = 3). The experiment was repeated three times with similar results. FL, firefly luciferase.