FIG 4.

The G94/G116R mutation confers IFN-β resistance to the WT virus. (A) Jurkat cells were treated with 200, 20, 2, or 0 U per ml of IFN-β for 16 h prior to infection. Cells were infected with VSV-G-pseudotyped HIV-1 isolates encoding the GFP reporter gene. The percentage of GFP-positive cells was determined at 2 days after infection. One representative result of at least three independent experiments is shown, with error bars denoting the standard deviation (SD) of the mean of triplicate measurements. (B) The relative IFN-β sensitivity (compared with that in untreated cells [in percent]) was calculated at 2 days after infection by dividing the percentage of GFP-positive cells among IFN-β-treated cells by the percentage of GFP-positive cells among untreated cells. The mean of nine independent experiments is shown, with error bars denoting the standard error of the mean (SEM). ****, P < 0.0001; ***, P < 0.001; **, P < 0.01. (C) Jurkat cells were left untreated or treated with 100 U per ml of IFN-β for 16 h prior to infection. Cells were challenged with NL4-3 viruses normalized to 1,000 pg per ml. Half of the culture medium was replaced with fresh medium every 3 days, and the concentration of reverse transcriptase (RT) in the culture supernatant was quantified by the SG-PERT assay. The results of two independent experiments are shown, with error bars denoting the standard deviation (SD) of the mean of triplicate measurements. Note that the values for the WT virus in each experiment were also used in Fig. 3I.