Fig. 3.
MCMVHA immunization induces robust immune protection but a poor IVL-specific CD8+ T-cell response. A, B C57BL/6 female mice were immunized f.p. with 2 × 105 PFU of MCMVHA or MCMVΔm157 virus. After 21 days, the mice were challenged with IAV (100 HU). A Body weight loss and (B) survival rates were measured. C–G BALB/c mice were infected i.p. with 2 × 105 PFU of MCMVHA or MCMVIVL. C Blood leukocytes were isolated and stimulated in vitro with IVL peptide for 6 h and analyzed by intracellular cytokine staining (ICCS) by flow cytometry at the indicated dpi. The percentages and numbers of IVL-specific CD8+ T cells in peripheral blood are shown as averages ± SDs (n = 6–10). D–G Immunized mice were challenged with IAV (1100 FFU, i.n.) at > 3 months p.i. Blood leukocytes were stimulated in vitro with IVL peptide for 6 h and analyzed by ICCS by flow cytometry on Day 7 post-challenge. Each symbol represents an individual mouse sample. (E) IAV titers measured by focus-forming assay (FFA) in the lungs on Day 5 post-challenge. Each symbol represents an individual mouse. F Average body weight loss upon IAV challenge at the indicated time points (n = 6–9). G Titers of HA-specific antibodies in serum samples on Day 5 after IAV challenge. The titers were detected by HA inhibition assay, n = 6–9. Each symbol represents an individual mouse. All of the above data are pooled data from two independent experiments. The Mann–Whitney U test was used for statistical analysis. ** p < 0.01, *** p < 0.001, **** p < 0.0001