Figure 2.

Effect of H5N1 polymerase mutations on viral growth in human airway epithelial cells at 37 °C. (A) A549 cells and (B) Calu-3 cells were infected with the indicated VN/HN viruses at an MOI of 0.03 and incubated at 37 °C. The culture supernatants were harvested at the indicated times and assayed by focus-forming assays to determine the progeny virus titers. Each data point is the mean ± SD of the log₁₀ FFU/ml from three separate experiments. An asterisk indicates a P value < 0.01 (ANOVA with Tukey’s multiple comparison test).