Intracellular cytokine staining and flow cytometry analysis indicated significantly enhanced levels of M2e-specific IFN-γ+ CD4+ T cells and IFN-γ+ CD8+ T cells in the airway bronchoalveolar lavage fluid (BALF) and lung samples in the adjuvanted M2e-H3 stalk group compared to those in naïve mice collected day 6 post infection (Figs. 7E–H and Supplementary Fig. S10). Here, CD4 is linked to infection.