B6 mice or F1(BALB/c × B6) mice receiving BALB/c.CD11cDTR bone marrow (BALB/c.CD11cDTR→F1) were seeded with naive OT-I.CD45.1 and memory OT-I.GFP T cells before infection with VSV-OVA. BALB/c.CD11cDTR→F1 chimaeras were treated with diphtheria toxin (+) or were left untreated (−). On day 7 after infection, spleens were recovered and the proportion of OT-I cells of the total CD8+ T-cell population was determined by flow cytometry. a, Representative flow cytometry profiles of the spleen gated on CD8+ T cells. b, c, The absolute numbers of memory OT-I.GFP (b) and naive OT-I.CD45.1 (c) T cells in the spleen on day 7 after infection are shown. Data are pooled from two independent experiments with 4–5 mice per group. Shown is the mean + s.e.m. d, Naive (CD45.1) or memory (GFP+) OT-I T cells were adoptively transferred into mice before infection with VSV-OVA. Representative pictures of the spleen on day 2 after infection showing staining for B220 (purple), CD11c (blue), CD45.1 (naive OT-I; yellow) and GFP (memory OT-I; green) are shown.