FIG. 4.

Chlorpromazine inhibits infection by RSV. The clathrin endocytosis inhibitor, chlorpromazine, was used at the indicated dosages to confirm that RSV required clathrin-mediated endocytosis for infection. Cells were treated following the same regimen as described in the Fig. 1 legend, with 1 h of pretreatment of cells and removal of the drug 5 h after the addition of virus. The cells were infected with recombinant RSV encoding red fluorescent protein (open bars) or with a VSV-G (solid bars) or 10A1 MLV (bars with diagonal stripes) envelope protein-pseudotyped retrovirus encoding GFP. Infected cells were counted by microscopy and the results were normalized to those for the untreated control for each virus. The means ± 1 SD of the results of three replicate experiments are shown.