Fig. 2.

Increased dependence on the CCR5 N terminus by MVC-Res Env. Luciferase reporter viruses pseudotyped with MVC-Sens Env (A) or with MVC-Res Env (B and C) were used to infect U87-CD4 cells expressing equivalent levels of WT CCR5 or CCR5 with alternative mutations in the N terminus, as described in Materials and Methods, in the absence (A and B) or presence (C) of MVC. The CCR5-expressing cell populations were generated and characterized with regard to their CCR5 expression levels as described previously (66). The level of virus entry into cells expressing a particular CCR5 mutant was expressed as a percentage of entry into cells expressing WT CCR5. The data shown are means and standard errors from a compilation of 4 independent experiments. Asterisks indicate the significance (P < 0.05) of the increase in dependence on a particular residue over that of MVC-Sens Env (*) or over that of MVC-Res Env in the absence of the drug (**) (determined by an unpaired t test).