Fig. 7: Adjuvanted M2e-H3 stalk vaccine induces protective T-cell immunity.

Cytokine-secreting T-cell immune responses were evaluated in M2e-H3 stalk immunized mice at 6 days post-infection with A/Nanchang H3N2 virus. A–D IFN-γ+ secreting ELISpot assays of spleen cells after in vitro antigen stimulation with M2e- (A) or stalk (B), and in Lung cells stimulated with M2e (C) or Stalk (D). E–H IFN-γ⁺ CD4⁺ or CD8⁺ T cells responses in BALF and Lung cells were determined by intracellular cytokine staining and flow cytometry analysis. IFN-γ⁺ CD4⁺ T cells response in BALF (E) and Lung (F). IFN-γ⁺ CD8⁺ T cells response in BALF (G) and Lung (H). Mock: mock group (adjuvant only) with virus infection. Naïve: mice group with no immunization and no virus infection. Impact of CD4⁺ and CD8⁺ T-cell depletion on protection in M2e-H3 stalk vaccinated mice before challenging with A/rgH7N9 virus (I). Statistical significance was determined by using one-way ANOVA followed by Tukey’s Multiple Comparison Test or two-way ANOVA followed by Bonferroni post-test; error bars indicate mean ± SEM; *P < 0.05; **P < 0.01; ***P < 0.001.