Figure 4.

Conditioned medium relieves an early postentry block of HIV infection in tissue-derived naive CD4 T cells. (A) Cells cultured in medium alone or conditioned medium were exposed to NL4-3 virions (250 ng of p24-Gag) containing BlaM-Vpr for 2 h before performing the virion-based fusion assay (reference 24 ). As a negative control, 250 nM of AMD3100, an inhibitor of CXCR4-mediated entry, was included. Data are representative of three experiments, during which levels of fusion ranged from 5 to 12% in the cell population. (B) Cells were exposed to VSV-G–pseudotyped NL4-3 HSA R-E- (700 ng of p24-Gag) for 3 h, washed extensively, and stained for surface expression of HSA 4 d later. Select cultures were treated with 10 μM 3TC as a control. Similar results were obtained in four additional experiments, with levels of HSA infection ranging from 0.7 to 4.0% in the cell population.