Fig. 8: CD8 T cells infiltrating the lung after MuHV-4 infection are necessary and sufficient to protect from PVM primary infection.

a–d BALB/c mice were infected or not with MuHV-4, submitted to PVM vaccination, challenged i.n. 30 days later with 3·10² PFU of PVM and treated i.p. with anti-CD8 depleting antibodies (100 μg) or isotype controls at days −4, −2, 0, and 2 after PVM i.n. challenge. Mice were euthanized at day 5 after PVM challenge. Experimental outline (a). Absolute numbers of effector memory CD8 T cells and of IFNγ + effector memory CD8 T cells in lungs (live CD45⁺ non-autofluorescent CD11c⁻CD11b^-CD3⁺CD8) (b). Absolute numbers of eosinophils (live non-autofluorescent SSC^hiCD11b^intSiglecF⁺), and of neutrophils (live non-autofluorescent CD11c⁻SSC^intCD11b⁺Ly6G⁺) in BALF (c) or in lung (d). (e–i) BALB/c mice were infected or not with MuHV-4, challenged i.n. 30 days later with 3·10² PFU of PVM, and treated i.p. with anti-CD8-depleting antibodies (100 μg) or isotype controls at days −4, −2, 0, 3, 5 after PVM i.n. challenge. Mice were euthanized at day 7 after PVM challenge. Experimental outline (e). Absolute numbers of effector memory CD8 T cells and of IFNγ⁺ CD8 T cells in lungs (live CD45⁺ non-autofluorescent CD11c⁻CD11b⁻CD3⁺CD8⁺CD62L⁻CD44^hi) (f). Quantification of infectious PVM virions in lungs (g). Comparison of weight curves (h) and of clinical score (i) between groups. (j–n) CD8 T cells were purified from CD45.2+ BALB/c mice infected for 1 month with MuHV-4 and adoptively transferred into Mock CD45.1 BALB/c mice previously submitted or not to the FI-PVM vaccine protocol. Recipient mice were then challenged i.n. with 3·10² PFU of PVM and euthanized 6 days later. Experimental outline (j). Representative flow plots of CD45.1⁺ and CD45.2⁺ CD8 T cells (live CD45⁺non-autofluorescent CD11c⁻CD11b⁻CD3⁺CD8⁺) isolated from BALF (k) and lung (l) of PVM challenged recipient mice. Comparison of weight curves between groups (m). Absolute numbers of BALF and lung eosinophils (gated as in c, d) (n).