FIG 6.

Lower inoculation doses of EEEV mutants do not make them less virulent. (A) CD1 mice (4-to-5 weeks old) were infected with the same dose of 5 × 10³ PFU of parental EEEV and the designed mutants, or mock-infected (PBS). No deaths were detected after day 12 PI. Survival analysis was performed in GraphPad software. Numbers on the graphs indicate MSTs. The significance between survivals of mice infected with wt EEEV and mutants was estimated using a log rank test; ***, P < 0.001. (B) Weight changes detected in individual mice infected with the indicated viruses or mock-infected (PBS). Black lines correspond to the mice that survived the infection and red lines correspond to the mice that succumbed to the infection. (C) Levels of viremia and brain titers (means with SD [where applicable]) at days 1 and 3 PI. Panels show the levels of viremia and brain titers as means with SD (where applicable) at days 1 and 3 PI. Significance of differences was determined by 2-way ANOVA without correction for multiple comparisons: nonsignificant (n.s.), P > 0.05; **, P < 0.01; ***, P < 0.001.