Effect of Debio-025 on the infectivity of recombinant viruses. Target cells, [U373-X4 (filled green circles), P4 cells (open black circles), MTR-R5 cells (filled red circles), CEM cells (filled purple circles), and H9 cells (filled blue circles)] were cultured in the presence of serial dilutions of Debio-025 and infected with 100 ng p24/ml (all recombinant viruses except NL4-3) or 20 ng p24/ml (NL4-3) of the indicated recombinant viruses. Luciferase activity (RLU) expressed by target cells was determined 40 h after infection. The results are expressed as a percentage of luciferase activity in cells cultured in the absence of Debio-025. As indicated in the Materials and Methods, several dilution schemes were used in the course of these studies; each data point represents pooled data for cells incubated the presence of a range of concentrations of Debio-025 as follows: 5 μM (2–5 μM), 1 μM (0.5–1 μM); 200 nM (125–200 nM); 40 nM (30–40 nM); 8 nM (8–10 nM); 1.6 nM (1.6 nM). The results shown are the mean ± SEM for 6 independent experiments (U373-X4, P4, MT4-R5) or 3 independent experiments (CEM, H9).