FIG 7 .

WT and mutant virus thermostability. Stocks of WT and H348/352A mutant virus were incubated at 50°C for the indicated times and the number of infectious particles determined by plaque assay. The graph shows averages and standard deviations of data from 4 independent experiments. The P values from 4 independent sample t tests for each of the 4 comparisons described above were 0.002, 0.002, 0.0006, and 0.00005 (left to right, respectively). Using a Bonferroni-corrected alpha of 0.0125 for each test, all 4 were statistically significant.