To test the extent to which Ly6C± naïve CD8 T cells have enhanced effector responses following infection, we co-adoptively transferred equal numbers of TCR-transgenic Ly6C+ (Thy1.1/1.1) and Ly6C- (Thy1.1/1.2) naïve P14 CD8 T cells into Thy1.2/1.2 recipient B6 mice 1 day before challenge with several distinct viruses (including LCMV Arm and Clone 13 strains, Vaccinia virus) expressing the GP33 epitope (Fig 2A and 2B). This evidence concerns the gene CD8A and infection.