FIG 11.

Hemagglutination inhibition (HAI) serum antibody. HAI titers were determined for each group of preimmune ferrets (n = 4) from blood collected at day 125 postvaccination. Preimmune ferrets were vaccinated as follows: (A) mock; (B) CA/07 rHA vaccine; (C) P1 rHA vaccine; (D) X6 rHA vaccine; (E) V3 rHA vaccine; (F) V6 rHA vaccine; (G) V12 rHA vaccine. The collected sera were tested against a panel of 9 H1N1 influenza viruses. Values are the geometric mean titers plus standard errors of the means (SEM) (error bars). The dotted lines indicate the 1:40 to 1:80 HAI titer range. All data are reported as absolute mean values ± SEM. HAI titers were compared using nonparametric one-way ANOVA. All statistical analysis was performed using GraphPad Prism 7 software (GraphPad, San Diego, CA, USA), and a P value of <0.05 was considered statistically significant (*, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001).