Fig. 9. Spike-specific CD4⁺ T cell responses.

C57BL/6 mice were vaccinated according to Fig. 5A. Lung (B and C) and spleen homogenates (D) were restimulated with a peptide pool covering major parts of S. The responding CD4⁺ T cells were identified by intracellular staining for accumulated cytokines. A Representative contour plots showing IFNγ production in iv+ and iv− lung CD4⁺ T cells. The gating strategy is shown in Supplementary Fig. 3. Bars represent group means overlaid with individual data points; all groups n = 4 (exception: n = 3 for DNA-Ad5 in D). Data were analysed by one-way ANOVA followed by Tukey’s multiple comparison test. Statistically significant differences are indicated only among the different vaccine groups; p values indicate significant differences (*p < 0.05; **p < 0.005; ***p < 0.0005; ****p < 0.0001). poly; polyfunctional T cell population positive for all assessed markers. Representative data from one out of three independent experiments with slightly different end time points are shown.