FIG 5.

Virulence of chimeric viruses following i.p. and i.c. inoculation. (A) Three- to 4 week-old female Swiss Webster mice were infected with 100 PFU of virus i.p. (n = 10 or 14). (B) Swiss Webster mice were infected with WNV NY99 (n = 5 per group) or an EIII chimera (n = 5 per group for WNV/JEV-EIII, n = 10 per group for WNV/KOUV-EIII, WNV/SLEV-EIII, and WNV/BAGV-EIII) at 100 or 10 PFU via the i.c. route. For the mice that succumbed to infection, average survival times (ASTs) with standard deviations were calculated and are shown on the right. Comparison of the mortality curves for mice infected with the chimeric viruses and those for mice infected with WNV NY99 for statistically significant differences was performed using a log-rank (Mantel-Cox) test (*, P < 0.05; **, P < 0.01; ***, P < 0.001). Comparison of the average survival times of mice infected with the chimeric viruses and those of mice infected with WNV NY99 for statistically significant differences was performed using a two-tailed Student's t test, with statistically significant differences being indicated in bold (P < 0.05).