Figure 3.

Virulence of DKR/FSS chimeric viruses in the A129 mice. Eight-week-old A129 mice (n = 7 mice per group) were intraperitoneally infected with 10³ PFU of DKR, FSS, CH-I, CH-II, or DPBS mock. (A) Viremia. The limit of detection (L.O.D.) for viremia was 100 PFU/ml. Each data point represents the mean level of viremia from 6 mice. (B) Survival analysis. Mice were euthanized once weight loss exceeded >20%. (C) Viral loads in organs of infected A129 mice. Organs were collected and homogenized on day 6 (top panel) and 9 (bottom panel) post-infection. The amounts of viruses were quantified on Vero cells using plaque assay. The averages results from four (at day 6 p.i.) or three (at day 9 p.i.) animals are presented. Bars denote standard error. All mice from group DKR died before collection date at day 9 post-infection. Two-way analysis of variance (ANOVA) was performed to analyze the statistical differences between the titres of each virus at the indicated time points and tissues. *, P < 0.05 (significant); **, P < 0.01 (very significant).