CD4 and infection: Although the frequency of total TFH cells and GC TFH cells was also comparable between WT and Ddb1-TaKO SMARTA CD4+ T cells at day 8 after LCMV Armstrong infection, the absolute numbers of total TFH cells and GC TFH cells were much lower in Ddb1-TaKO SMARTA CD4+ T cells than that of WT counterparts, due to severe defect of expansion in Ddb1-TaKO SMARTA CD4+ T cells (Figures 3D, E).