Specific humoral responses elicited after immunizations with different adjuvant-NG34 combinations. Serum samples from individual mice from groups A–F were collected after second immunization and analyzed in serial dilutions for IgG1 and IgG2c titers. A NG34-specfic IgG1 and B IgG2c antibody titers and HA1-specific C IgG1 and D IgG2c antibody titers. Adjuvanted groups were compared to group B (the non-adjuvanted group) using a non-parametric test (Friedman test) followed by Dunnett’s post-test. *P < 0.05; **P < 0.01, *** P < 0.001, ****P < 0.0001.