FIG. 3.

Effect of coreceptor utilization on sensitivity to fusion inhibitors. JC53-BL indicator cells were infected with each chimeric virus in the presence of increasing concentrations of T-649 (left) or T-20 (right). Inhibitor concentrations are plotted along the horizontal axes. Luciferase activities in the infected cell lysates were measured at 48 h postinfection and were used to calculate virus infectivity relative to that of the control (vertical axes) and IC₅₀s for each inhibitor. (A and B) Comparison of the infectivity of NL4.3 (DIV) and the JRFL-derived CCR5 V3 loop chimeras in the presence of T-649 and T-20, respectively. (C and D) Comparison of the infectivity of NLHX and the four CCR5-specific V3 loop chimeras in the presence of T-649 and T-20, respectively. (E and F) Comparison of the infectivity of two additional NL4.3-derived viruses that differed only in substitution of JRFL V3 loop in the presence of T-649 and T-20, respectively. (G) Chimeric constructs that correspond to the infectivity graphs.