(A) Flow cytometry analysis of germinal center (GC) cells (CD19+, GL7+, and CD95+) as a percentage of total spleen B cells. Each circle is the analysis of an individual mouse 14, 16, or 18 days postinfection (dpi) via intranasal (IN) or intraperitoneal (IP) MHV68-H2BYFP inoculation. Naïve, uninfected mice were used as control. (B) Summary of YFP+ (MHV68-YFP+) cells as a percentage of total splenic B cells. (C, D) Isotype expression profile of total GC B cells or (D) YFP+ GC B cells from the spleen of control naïve, IN, or IP inoculated mice at the indicated dpi.