On day 8 after infection with the LCMV Armstrong strain, Ezh2fl/flCd4-Cre mice exhibited a remarkable reduction in the virus-specific GP66–77 tetramer-positive CXCR5+ICOS+ TFH cell population in the spleen compared to that in Ezh2fl/fl control mice (Fig. 4a, b). Here, CXCR5 is linked to infection.