Figure 7.

Lung elevated cytokine production and secretory‐specific IgA, along with high serum H3‐stem antibodies in A‐eIIV mice after challenge. Mice were challenged with 20LD₅₀ H3N2‐1968 virus 21 days or 6 months post‐vaccination, and inflammatory responses were sampled at day 7 post‐infection. Inflammatory cytokine and chemokine concentrations in individual lung homogenates (n = 4) by CBA were normalised to fold change from PBS response (a). H3N2‐1968 VNA endpoint titres from serum from short‐term challenge at day 7 post‐infection (b). In vitro protection assay of H3N2‐1968‐infected Raji cells with mouse serums from 7 and 21 days post‐infection (n = 3 or 4), responses were normalised to naïve mouse serum (c). Day 7 post‐challenge, H3N2‐1968 HA‐specific secretory IgA in BALF for short‐ and long‐term memory recall measured by ELISA (d), normalised to total protein concentration by BCA. H3N2‐1968 HA and H3‐stem‐specific IgG responses by ELISA for short‐ and long‐term memory recall at day 21 post‐challenge (e). Data represent the mean, SEM and individual responses, n = 4 mice per group. *shows statistical significance of eIIV versus S‐IIV. *P < 0.05, **P < 0.01 and ***P < 0.005, experiments were repeated twice.