Twenty-four-day-old C57BL/6J mice were inoculated with 103 PFU of RR64 (filled circles), RR87 (open circles), RR94 (filled squares), or RR100 (open squares) by injection in the left rear footpad. At 1, 3, and 5 dpi mice (n = 3–6) were sacrificed, blood was collected via cardiac puncture, and mice were perfused by intracardial injection with 1X PBS. Tissues were dissected, weighed, homogenized and the amount of infectious virus present was quantified by plaque assay on BHK-21 cells. Dashed lines indicate the limit of detection. *P≤0.05, **P≤0.01, ***P≤0.001 as determined by ANOVA.