Figure 4

Cytotoxic CD8⁺ T cells control acute MNV-1, but not MNV-3, infection. (a) Groups of B6 (black bars) and CD8^−/− (white bars) mice were infected p.o. with 10⁷ TCID₅₀ units MNV-1 or MNV-3. At 3 d.p.i., the indicated tissues were dissected and viral titers were determined by plaque assay. The data are reported as pfu per gram of tissue and the data for all mice per group (n=6–8 mice over three experiments) are averaged. Dashed lines indicate the limit of detection for each tissue. The two mouse strains were compared for each tissue and virus strain for statistical purposes. (b) Peyer’s patch cell suspensions prepared from groups (n=2–3) of mock-inoculated B6 mice (black bars), or B6 mice infected p.o. for 3 days with 10⁷ TCID₅₀ units MNV-1 (gray bars) or MNV-3 (white bars), were stained for surface CD8, NK1.1, CD4, or CD19 and intracellular GrB. The experiment was repeated five times for a total of 13 replicates per condition. The data are presented as the percentage of the indicated cell populations expressing GrB in the left panel; no GrB was detected in CD4⁺ and CD19⁺ populations (data not shown). The data are presented as total numbers of GrB-producing CD8⁺ T cells in the right panel. (c) Peyer’s patch cell suspensions were stained for surface CD8 and the T cell receptor (TCR) β chain (as an indication of αβ T cells) or the TCR δ chain (as an indication of γδ T cells), and intracellular GrB. The overall frequencies of αβ and γδ CD8⁺ T cells expressing GrB are presented in the left panel. The total numbers of the GrB-expressing subsets are presented in the right panel. In panels b and c, the mock group was compared with each virus group, and the two virus groups were compared, for statistical purposes. (d) IEL prepared from mock-inoculated (black bars) and MNV-1-infected (gray bars) wild-type B6 and B-cell-deficient μMT mice at 3 d.p.i. were stained for surface CD8 and intracellular GrB. The experiment was repeated six times for a total of six replicates per condition. The data are presented as the total number of GrB-producing CD8⁺ IEL per condition. The mock group was compared with the infected group for each mouse strain for statistical purposes. d.p.i., days post infection; GrB, granzyme B; IEL, intestinal epithelial lymphocyte; p.o., perorally.

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