FIG. 10.

Fusion conditions and dose-dependent fusion inhibition. Panel A: time course of fusion. Cells were infected and then exposed to inactivating antibody in the absence (filled bars) or presence (open bars) of 100 μM TAT-Cd⁻ as described in the legend to Fig. 10. β-Galactosidase activity was measured in lysates at the times indicated. Panel B: inactivating antibody concentrations. Antibody concentrations required for inactivation of extra cellular virus were determined by measuring inhibition of entry of hrR3 adsorbed to cells for 2 h at 4°C (MOI, 0.05). The infected cultures were exposed to various antibody dilutions for 1 h at 4°C and for 6 h at 37°C before β-galactosidase activity was measured in cell lysates (100% antibody concentration corresponds to a 10-fold antibody dilution). Panels C, D: dose-dependent inhibition of fusion. Cells were infected for 1 h at 37°C (MOI, 0.02) and then exposed to inactivating antibody and various concentrations of peptides for 24 h, at which time β-galactosidase activity was measured. (C) TAT-Cd⁻ inhibited fusion (•; EC₅₀, 1.9 μM) in the absence of cytotoxic effects (trypan blue exclusion; ○). (D) TAT-C⁻ and n_50,51TAT-C⁻ inhibited fusion with EC₅₀s of 2.1 (▴) and 60 μM (▵), respectively. The data points represent the means of triplicate determinations with standard errors of the means.