Apoptosis of PLC after MCMV infection is STAT4-dependent. (A) Comparison of PLC numbers in spleen (left) and BM (right) of PBS- (blue) or CMV-injected (red) 1-week-old Eμ-ret pups at 6 and 10 dpi (Mann-Whitney t test; n = 7 PBS and 10 CMV neonates; pooled results from 3 independent experiments). (B) Representative images of bioluminescence in 1-week-old Eμ-ret pups infected with luciferase-tagged CMV and uninfected controls at 3, 6, and 10 dpi. (C) Polymerase chain reaction for detecting CMV DNA in 3 different concentrations of virus equal to 200, 20, and 2 pfu as controls, 3 unsorted total splenocytes, and 3 sorted PLC samples from spleens of wild-type Eμ-ret pups 7 days after infection from 3 independent experiments. (D) Comparison of PLC numbers in representative (left panels) or cumulative (right panels) spleens of PBS- or CMV-injected Stat4–/– (R/Stat4) and Stat6–/– (R/Stat6) Eμ-ret pups at 10 dpi (Mann-Whitney test; R/Stat4, n = 11 PBS and 10 CMV; R/Stat6, n = 5 PBS and 8 CMV; pooled results from 3 independent experiments). (E) Representative (left panel) or cumulative (right panel) bioluminescence in wild-type (R/wt) and Stat4–/– (R/Stat4) Eμ-ret pups at 3, 6, and 10 dpi with luciferase-tagged CMV (2-way analysis of variance [ANOVA]; n = 5-10) (for simplicity, nonsignificant comparisons are not labeled). (F) Cumulative results for assessment of caspase 3/7 activity in PLC (CD19+, BP1+) from spleen and BM of Eμ-ret pups 7 days after PBS (Ctrl) or virus (CMV) injection (Mann-Whitney t test; PBS, n = 6; MCMV, n = 7). Data shown as mean ± SEM. ns, not significant; ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; ∗∗∗∗P < .0001.