FIG 7.

Viral loads following inoculation of parental strains and the reciprocal E2 82 variant strains. C57BL/6J mice (20 to 22 days old) were inoculated with PBS or 10³ PFU of virus strain AF15561, 181/25, AF1561 E2 G82R, or 181/25 E2 R82G in the left rear footpad. At days 1, 3, and 5 postinoculation, mice were euthanized, their ankles, quadriceps (Quad), and spleens were excised, and serum was collected. Viral titers in tissue and serum homogenates were determined by plaque assay using BHK-21 cells. Results are expressed as the mean PFU/gram (tissue) or PFU/ml (serum). Error bars indicate standard errors of the means. Dashed lines indicate the limit of detection. The number of mice at different time points follow: D1, n = 5; D3, n = 7; D5, n = 5. Values that are significantly different as determined by ANOVA followed by Bonferroni's posthoc test are indicated by asterisks and bars as follows: *, P < 0.05; **, P < 0.01; ***, P < 0.001.