CD8A and infection: At day 8 post Cl13 infection, a significantly lower frequency and absolute number of either GP33- or NP396-tetramer-positive CD8 T cells, indicating viral-specific CD8 T cells, were observed in both the spleen and liver of Tcf7fl/fl-CD4Cre mice than those of WT (Tcf7fl/fl, WT) mice (Figure 2A, Supplementary Figure 1A).