Fig. 6.

Protective efficacy against heterologous influenza virus challenge. (A) Morbidity and (B) mortality of mice after challenge. (C) Cross-protective IgG endpoint titers against the Phi virus in mice boost sera. (D and E) Phi virus-specific IgG and IgA levels in BALF. (F) Phi virus-specific IgA levels in nasal washes. (G) Serum hrHA3-specific antibody levels. (H and I) IL-4– and IFN-γ–secreting splenocytes under inactivated Phi virus stimulation. The data are presented as mean ± SEM. The statistical significance was analyzed by one-way ANOVA followed by Tukey’s multiple comparison test (*P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001; ns represents no significance, P > 0.05).