FIG 3.

Hemagglutination inhibition (HAI) serum antibody titers induced by vaccination of mice with V1, V2, or V3 VLP vaccines. HAI titers were determined for each group of mice (n = 11) from blood collected at week 12 postvaccination. Mice were vaccinated with either COBRA, VIPER, or wild-type HA VLP vaccines and 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. (A) Bris/07 VLP; (B) CA/09 VLP; (C) X6 VLP; (D) P1 VLP; (E) V1; (F) V2 VLP; (G) V3 VLP; (H) mock. 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).