FIG. 4.

Cholesterol depletion inhibits productive infection by receptor-mediated membrane fusion but not endocytosis. CEMx174 cells, untreated (control) or treated for 30 min with 10 mM MβCD, were infected for 1 h with envelope-defective NL4-3 Env⁻ LUC⁺ virions alone, [Env(−)] or with virions pseudotyped with HXB2 or VSV envelope (5 cpm of RT/cell). After extensive washing, the cells were cultivated and collected 48 h later. Luciferase activity in 10 μl of cell lysates (expressed as relative light units) was determined using luciferase assay reagent as described in Materials and Methods. As a control, the cells were pretreated with anti-CD4 Q4120 (10 μg/ml) for 30 min before infection with viruses. The results are representative of two independent experiments.