FIGURE 4.

Protective memory CD8 T cell responses in E8_I^−/− mice. A–C, WT and E8_I^−/− mice were infected with LCMV-Armstrong, and ~50–55 days later, the mice were reinfected with LCMV-cl.13 and analyzed 8 days later. A, Bar graph shows cl.13 virus titers in the spleen at day 8 p.i. Naive mice were infected for a positive control of infection. Dashed line denotes level of detection. B, Bar graph shows the combined numbers of D^bNP_396–404, D^bGP_33–41, and D^bGP_276–86-specific CD8 T cells in the spleen 8 days p.i. that were calculated based on MHC class I tetramer staining. C, IL-7Rα expression on NP_396–404- and GP_33–41-specific CD8 T cells 8 days p.i. Left panels show percentage of CD8 T cells (bottom numbers) and tetramer⁺ CD8 T cells (top numbers). Right panels show percentage of IL-7Rα^hightetramer⁺ CD8 T cells. Note the reduction in CD8α expression on tetramer⁺ CD8 T cells in E8_I^−/− mice; these CD8α^low cells were not included in the calculations shown in B.