Both the total number of OT-I CD8 T cells (Fig. 2A) as well as the number of OT-I cells that had undergone at least one division (CFSELO, Fig. 2B, with representative CFSE profiles in Fig. 2C) increased two to fourfold when transferred into adult mice between 3 and 5 days post-infection, suggesting a window of time during which conditions were optimal for expansion of naïve OT-I cells. Here, CD8A is linked to infection.