Fig 3.

Efficiency of one round of HIV-1 R5 infection correlates with CCR5 density on the target cell. HOS^low (▪) and HOS^high (•) cells were exposed to env-defective HIV-1 R5 virus harboring the luciferase marker gene and pseudotyped with an R5 envelope at various quantities (A) or pseudotyped with the G protein of the VSV at the same quantities (B) or at 150-fold lower quantities to result in equal viral copy number entering the cells (C). Luciferase activity was measured in cell lysates 72 h later.