In analyzing antibody responses against NP protein (Figure 2 , middle panel), the result of the ANOVA was a borderline p-value of 0.0504. Pairwise comparisons between the HA alone and HA+NP group were similar (p = .0080 with a Bonferroni-adjusted threshold of .05/6 = .0083). However, when analyzing antibody responses against M2 protein, DNA vaccination with M2 in combination with both HA and NP elicited a significant humoral response compared to controls (p,0.0001) (Figure 2, right panel) . This result suggests that M2 is immunogenic, although immunization with M2 alone was not included in this study. To define the neutralizing antibody responses, mouse sera were pooled by groups and pseudotype neutralization, and microneutralization assays were performed. These analyses revealed neutralization activity in the HA group, with lower titers in animals immunized with HA+NP and lowest responses in those vaccinated with HA+NP+M2 (Table 1) . However, minimal neutralization was evident in NP-only immunized animals. HAI assays were not performed on the mouse sera.