Susceptibilities of recombinant pseudotyped viruses to CXCR4 inhibitors determined by single-round entry assays.

aNP2/CD4/CXCR4/CCR5 cells (1.5×104) were infected with pseudotyped virus (50 ng p24Ag) in the presence of CXCR4 inhibitors, and then the luciferase activity was measured at 48 h post-infection to determine the effective concentration of 50% entry inhibition (EC50).bMean ± SD (n = 3). Numbers in parenthesis represent fold changes of EC50 values compared with that of the wild type.