FIG 7.

Detection of cytokine proteins in lungs of mice infected with H9N2 mutant viruses. Nine mice per group were either inoculated with 10⁶ TCID₅₀ of the indicated mutant viruses or mock infected with PBS, and protein levels of cytokines in the lungs of three infected mice were determined at 1, 3, and 5 dpi. Data are presented as means ± standard deviations of results from three independent experiments. * indicates that the value is significantly different from that for the wild-type virus (P < 0.05 as determined by ANOVA), and # indicates that the value is significantly different from that for the virus with single mutation PB2-E627K (P < 0.05 as determined by ANOVA).