(A) Flow cytometric analysis of LTβ expression by lymphocytes from B6 and LTβ−/− spleens. Anti-CD4, CD8, and B220 mAb were used to identify B and T lymphocyte subsets. Filled histograms represent staining with isotype control mAb in B6 mice (B) B6, RAG−/− (lack B and T cells), RAG/γc−/− (deficient in T, B, and NK cells), and LTβR/RAG double-deficient mice and (C) B6-, B cell (B−/−)-, CD4+ T cell (CD4+−/−)-, and CD8+ T cell (CD8+−/−)-deficient mice were infected with MCMV (2 × 105 PFU i.p.). Spleens were harvested 8 hr postinfection and IFNβ and ie1 mRNA levels were determined by qPCR and normalized to the levels of 18S rRNA (top two panels of both [B] and [C]). IFNβ/ie1 mRNA ratio (×100) was calculated and serum INFα levels were determined by ELISA; ND, not detectable) (two lower panels). Statistical significance (*p < 0.05) was determined using the Student's t test, and fold differences are shown in parentheses. n = 4−6 mice per group ± SEM.