FIG. 4.
Point mutations L33S (for HIV-1NL4-3) and N126K (for HIV-1BaL) are sufficient to confer resistance to T-20 and T-649. TZM-bl cells were infected with 1,000 IU/well of the pseudotyped viruses carrying the parental envelope proteins of HIV-1NL4-3 and HIV-1BaL and the point mutations indicated (NL/S [L33S], BaL/V [I48V], BaL/K [N126K], and BaL/VK [I48V/N126K]) in the presence of increasing concentrations of T-20 or T-649 (0.02 to 10 μg/ml). Firefly luciferase activity was measured 48 h postinfection and is plotted on the y axis as percent infection relative to the control infection (without fusion inhibitor). Shown are the means of triplicate infections for each inhibitor concentration. These data were used to calculate IC50 values and the fold change of IC50 (see Table 1).