Figure 5.

H7N7 cross‐reactive A‐eIIV antibodies in mice and humans. H7N9‐HA‐specific IgG titres measured by ELISA in mice at 7 days post‐vaccination (n = 5 mice per group) (a). Correlation of H7N9‐HA and H3‐stem IgG titres in mice serum by the Pearson correlation, R ² = 0.624, P < 0.0001 (b). In vitro protection assay of H7N7‐infected Raji cells with mouse serum from 21 days post‐vaccination (pooled serum in triplicate, n = 3 mice per group) assessed by FACS (c), and responses were normalised to naïve mouse serum (d). In vitro protection assay of homologous H3N2‐2013, heterologous H3N2‐1968 or H7N7‐infected Raji cells with human pre‐ and 30‐day post‐vaccination serums (e), individual responses (n = 10 per group) for S‐IIV and A‐eIIV, and fold change post‐vaccination (f). Experiments were repeated twice. Data represent the mean, SEM and individual responses. In c, the percentage of the population of interest is shown in black on the FACS plots, and the ratio of the mean percentage versus naïve mouse serum (NMS) is shown in red. ^#shows statistical significance versus NMS, and *shows statistical significance versus S‐IIV. *P < 0.05, **P < 0.01 and ***/^### P < 0.005.