Fig. 1.

The R3A Env mediates elevated viral fusion with CD4+ T cells. Blam-vpr-containing virions were used to infect Sup-T1 cells by spinoculation. After 2 h of incubation at 37 °C, cells were incubated with flurogenic beta-lactamase substrate for 8 h. The amount of entry was calculated by measuring the ratio of cleaved to uncleaved flurogenic substrate. Shown is a representative of eight independent experiments with error bars derived from triplicate samples and input virus determined by p24 ELISA. (*P <0.05 for R3A vs. either NL4-3 or R3B).