FIGURE 3.

Impaired anti-viral B cell responses and increased clinical signs in CD2-Egr2^−/−Egr3^−/− mice. WT and CD2-Egr2^−/−Egr3^−/− (K2-3) mice were infected intranasally with 2 × 10⁵ pfu of vaccinia virus. A, splenic sections from WT and K2-3 mice 14 days postinfection were stained with PNA (red) and antibodies against CD4 (green) and IgD (blue). B, GC B cells (B220⁺GL7⁺) were analyzed in WT and K2-3 mice by flow cytometry 14 days postinfection, and the expression of BCL6 (bottom) was analyzed. C, GC B cells in these mice were quantified as a percentage of total B220 cells (gating as in B). D, EGR2 expression by B220⁺GL7⁺ cells in WT and K2-3 mice 14 days postinfection was analyzed. E, percentage weight loss of infected WT and K2-3 mice at the indicated time points. F, viral titer in lung tissue specimens from WT and K2-3 mice 8 days after infection. G, serum was collected from infected WT and K2-3 mice 3 weeks after infection, and the presence of antiviral antibody was assessed using a neutralization assay. The number of viral plaques in the presence of serum at the indicated dilutions is shown. Results are presented as mean ± S.E. (error bars) from groups of five mice of each genotype. C, each symbol represents an individual mouse from three independent experiments (indicated by different colored symbols); error bars, S.E. on either side of the mean. *, p < 0.0005 (Mann-Whitney two-tailed test). Data are representative of at least two independent experiments.