On day 8 post viral infection, we observed the percentages and numbers of CD44+CXCR5+ TFH cells derived from CD45.1+ SMARTA CD4+ T cells were similar in the Mettl3fl/flCd4-Cre mice and their wild-type counterparts (Fig. 2b, c), indicating the microenvironment in the Mettl3fl/flCd4-Cre mice did not impair TFH differentiation. Here, CD4 is linked to viral infectious disease.