Fig. 5.

H84T inhibits influenza virus fusion. MDCK cells were pretreated for 1 h at 37 °C with 1 or 10 μM H84T or 20 or 40 μM of the fusion inhibitor ARB and incubated with octadecyl R18-labeled A/WSN/1933 for 1 h at 4 °C to allow attachment only. Excess virus was removed and virus fusion with the cell membrane was triggered at 37 °C using pH ∼5.25 fusion buffer. Fluorescence dequenching of R18 was monitored on a microplate fluorometer with excitation and emission wavelengths of 560 and 590 nm, respectively. Maximal dequenching was achieved with 1% Triton X-100 set at 100%. Bars represent the mean values from duplicate wells from two independent experiments and error bars represent the SEM. Statistical analyses were performed by t test. *P < 0.05, **P < 0.01, comparing groups indicated by brackets.