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). This evidence concerns the gene CD8A and infection.