FIG 6.

Both the E2 K200R mutation and the deletion in the 3′-UTR contribute to enhanced viral pathogenicity in mice. (A and B) WT C57BL/6J mice were inoculated with 10³ PFU of AF15561 (n = 8), AF15561^{E2 K200R;ΔUTR} (n = 8), AF15561^{E2 K200R} (n = 8), or AF15561^ΔUTR (n = 8) in the left rear footpad. The percent starting body weight (A) and disease score (B) were determined daily. Data are derived from results from two independent experiments. P values were determined by two-way ANOVA with Bonferroni's multiple-comparison test. **, P < 0.01; ***, P < 0.001. The P values displayed are for AF15561^{E2 K200R;ΔUTR} versus AF15561^{E2 K200R}. (C) WT C57BL/6J mice were inoculated with 10³ PFU of AF15561 (n = 6), AF15561^{E2 K200R;ΔUTR} (n = 6), AF15561^{E2 K200R} (n = 6), or AF15561^ΔUTR (n = 6) in the left rear footpad. At 1 dpi, mice were euthanized, and the amount of infectious virus in the indicated tissues was quantified by a focus-forming assay. Data are derived from results from two independent experiments. P values were determined by a Kruskal-Wallis test with Dunn's multiple-comparison test. *, P < 0.05; **, P < 0.01; ***, P < 0.001.