TCF7 and infection: On the other hand, when deleting Tcf7 at an early stage of Cl13 chronic infection (4 days before infection) (Figure 4E), a significantly decreased frequency and total number of GP33-tetramer-positive CD8 T cells in the tamoxifen-treated group were observed at 25 days after infection (Figure 4F), accompanying the prominent increase in the expression of inhibitory receptors, such as PD1, Tim3, and 2B4 (Figure 4G).