FIG. 3.

Viral replication in the brains and livers of animals after intracranial inoculation. C57BL/6 weanling mice were infected with 10 PFU of MHV4 (●), S4R22 (▴), S4R21 (▵), and wtR13 (■). Animals were sacrificed at the indicated times, and virus titers in the brains (A) or livers (B) were determined by plaque assay. The limit of detection was 500 PFU/g of tissue. The data shown represent the means (and standard deviations) of the titers from eight (S4R22) or four (all other viruses) animals.