Figure 3.

Defective memory responses of N-ras–deficient mice upon VACV infection or DC immunization. WT and N-ras^−/− mice were either infected with rVACV-OVA (A–C) or immunized with a mixture of mDC loaded with B8R and OVA peptides (D–F). (A and B) On day 45 after infection, splenocytes and PBMCs were harvested and the frequency of B8R-specific T cells within the CD8⁺ population (A) and the number of B8R-specific splenic CD8⁺ T cells producing IFN-γ (B) were determined ex vivo (n = 4, two experiments). **, P < 0.005. (C) In vivo function of day 45 p.i. memory T cells was assessed in an in vivo killing assay (n = 6, two experiments). (D and E) On day 35 after DC immunization, the frequency of B8R- and OVA-specific T lymphocytes within the CD8⁺ population (D) and the number of B8R- and OVA-specific splenic CD8⁺ T cells producing IFN-γ (E) were determined ex vivo (n = 6, two experiments). (F) In vivo function of day 35 p.i. memory T cells was assessed in an in vivo killing assay (n = 6, two experiments). Results are expressed as mean ± SEM. ***, P < 0.0005.