Fig. 4.

Increased CCR5 dependence of MVC-Res Env in the presence of MVC. (A to C) 293-Affinofile cells were treated with increasing concentrations of minocycline and ponasterone A to induce 48 cell populations expressing different combinations of cell surface CD4 and CCR5 levels, as described in Materials and Methods, and were inoculated with equivalent infectious units of a luciferase reporter virus pseudotyped with MVC-Sens (A) or MVC-Res (B and C) Envs in the absence (A and B) or presence (C) of MVC. In the absence of the drug (A and B), virus entry levels were normalized against that in cells expressing the highest levels of both CD4 and CCR5. In the presence of the drug (C), levels of entry by viruses with MVC-Res Env were expressed as percentages of that attained when no drug was present. The results shown are means from 4 independent experiments, each performed in duplicate. Shaded wedges along each axis represent increasing concentrations of CD4 or CCR5, as described in Materials and Methods. (D) Graphical representation of the VERSA vectors showing the efficiency of entry (vector magnitude) and relative dependence on CD4 and CCR5 levels (vector angle). The shaded wedges represent the standard errors of the means of the vector angles, and the boxes represent the standard errors of the means of the vector magnitudes. The difference between the vector angles shown was statistically significant (P, 0.0018 by an unpaired t test).