FIG 1.

Brain invasion by hematogenously spread MHVs correlates with virulence. (A) Groups of six or seven mice were i.p. mock infected (PBS) or infected with 1,000 TCID₅₀ (50% tissue culture infective doses) of MHV3, MHV-A59, and 51.6-MHV3 for 72 h, and harvested brains were subjected to hematoxylin-eosin-safranin staining for histopathological analyses. (B) Viral detection of MHV3, MHV-A59, and 51.6-MHV3 at 72 h p.i. in brain samples of infected mice determined by qRT-PCR analysis of the viral nucleoprotein (N) expression and viral titration (TCID₅₀). The viral detection threshold is 1.6 TCID₅₀/ml. Values are means plus standard errors of means (error bars). Values that are significantly different (P < 0.001) are indicated (***).