FIG. 3.

Analysis of the effect of various protease inhibitors on HIV infection and on LTR activity. (A) Effect of MG132 on HIV-1 LTR activity. P4 cells were transfected with 1 μg of pLTRX-Luc and the indicated amounts of pCMV-Tat DNA. After 24 h, cells were pulse-incubated for 1 h with or without MG132 (50 μM), and 5 h later, luciferase activities in cell extracts were measured. Results are expressed as RLU per microgram of cellular protein. Values are means of triplicate determinations, and variation between each point was below 10%. (B) P4 cells were infected with HIV-1 (left panel) or HIVΔenv(VSV) (right panel) in the presence of the proteasome inhibitors MG132 (50 μM) or lactacystin (40 μM) or with calpain inhibitor I (50 μM) or calpain inhibitor II (50 μM) for 1 h and washed. Infections were revealed 24 h later by measuring β-galactosidase activity (optical density [O.D.] units). Data are representative of three independent experiments.