Figure 9.

Protective effect of antibodies induced by study vaccines in a passive serum transfer experiment. Serum samples from mice immunized with two doses of H7N9, H7N9+4M2e, or PBS were pooled and injected intravenously to naïve BALB/c mice 6 h prior to challenge with either 3 LD₅₀ of a mouse-adapted A/California/7/09 (H1N1pdm09) (A) or 1 LD₅₀ of A/South Africa/3626/2013 (H1N1pdm09) virus (B). Body weight loss (left) and survival rates (middle) were monitored for two weeks post-challenge. Area under the curve of body weight loss (right) was an additional measure of protection. Survival rates were compared by Mantel–Cox log-rank test. AUC values were compared by one-way ANOVA, followed by Tukey’s multiple comparisons test. * p < 0.05; ** p < 0.01.