TCF7 and viral infectious disease: We hence focused on the methylation status at TFH lineage related gene loci, including Tcf7, Bcl6, Id3 and Prdm1. The Tcf7 promoter was demonstrated as a target locus of DNMT3A, and the expression of DNMT3A was necessary to maintain the methylation status at Tcf7 promoter to restrict the frequency of memory precursor cells during acute viral infection (35).