FIG 5 .

HN adaptations to culture increase fusion promotion by viral fusion complex. Cells were cotransfected with the indicated HN in a clinical isolate background, reference F, and the α fragment of β-galactosidase. These cells were then allowed to fuse with cells expressing the Ω fragment of β-galactosidase for 24 h. Fusion was stopped by lysing the cells, and β-galactosidase activity was quantitated and normalized to HN expression. Every mutation in HN conferred increased fusion promotion relative to the clinical wild-type HN. Results depict means plus standard errors of the means (SEM) (error bars) from three biological replicates consisting of three technical replicates each. Mutants were compared with CI WT with one-way analysis of variance (ANOVA) following log transformation of data. Values that are statistically significantly different (P < 0.0001) from the value for the CI WT are indicated by an asterisk.