Next, we investigated how naïve CD8+ T cells integrate the distinct levels of TCR signals in vivo by FACS-sorting activated/divided (CFSElow) OT-I cells 3 days post-infection with Listeria monocytogenes (Lm) expressing either A8 or T4 APLs, or the N4 epitope and conducted whole genome expression arrays (Fig. 1b and Supplementary Fig. 1d). This evidence concerns the gene CD8A and infection.