FIG. 7.
Effect of the tyrosine kinase inhibitor herbimycin A on RANTES-induced infectivity enhancement. HeLa-CD4 cells were incubated for 25 h with the indicated concentrations of herbimycin A. The cells were then infected with HIV-1MuLV (2.5 ng of HIV-1 p24 antigen) in the presence (■) or absence (●) of 10 μg of RANTES/ml. Unbound virus was removed after a 2-h incubation period, and the cultures were replenished with fresh medium without RANTES. (a) RANTES was added to the cells 24 h before the initiation of infection (i.e., 1 h after herbimycin A was added) and then washed away immediately before the addition of virus. Neither RANTES nor herbimycin A was present during the 2-h infection period or thereafter. (b) RANTES was added to the cells simultaneously with the viral inoculum so that both RANTES and herbimycin A were present during the 2-h infection period but neither agent was present after that period. In both experiments, the extent of viral infection was determined by measuring luciferase expression in quadruplicate cultures on day 3 postinfection; the data are presented as percentages of control (no chemokine = 100%). The untreated control values were (a) 183 ± 63 RLU and (b) 262 ± 53 RLU.