FIG 5.

Sensitivity to anti-influenza therapeutics that target the fusogenic ability of hemagglutinin. (A and B) The sensitivity of HA mutants to 20 μM arbidol hydrochloride (a small-molecule fusion inhibitor) (A) and 1 nM bafilomycin (a vacuolar ATPase [vATPase] inhibitor) (B) was assessed by treating virus-infected MDCK cells with drug and titrating virus released at 24 h postinfection by plaque assay on fresh MDCK cells. One-way ANOVA with Tukey’s posttest was used to compare WT virus to the other viruses. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ns, not significant. (C to E) The sensitivity of WT and A9T viruses to arbidol hydrochloride (C), bafilomycin (D), and favipiravir (a nucleoside analogue) (E) at stated doses was tested by treating virus-infected MDCK cells with drug and titrating virus released at 24 h postinfection by plaque assay on fresh MDCK cells. Unpaired Student’s t test was used to compare the titers of WT and A9T viruses. *, P < 0.05; **, P < 0.01. Experiments are representative of at least two biological replicates.