As shown in Fig. 2, only vaccine formulations with the 0.5 μg and 1.5 μg antigens in AddaVAX-adjuvanted H7N7 whole-virus (lane I and lane S) can elicit the HAI titers over 40 after first vaccination (Fig. 2A, prime). After the second immunization, the resulting HAI titers against H7N7 virus illustrated that adjuvants indeed enhanced the immunogenicity of H7N7 vaccine either with a low-dose or high-dose vaccination (Fig. 2A). In addition, the squalene-adjuvanted H7N7 antigens elicited the highest geometric mean with

HAI titers ranging from 320 to 640 among the three experimental groups, suggesting the squalene emulsion is the most efficacious in stimulating specific HA antibodies (Fig. 2A). The determination of neutralizing antibody titers elicited by vaccination may be more relevant selleck compound to the assessment of vaccine efficacy because it is not clear that all HAI antibodies can accomplish viral-neutralization activity. To this end, microneutralization assay, as a measurement of antisera ability to neutralize viral infections to MDCK cells, were performed. The results showed that the mice immunized

with vaccines combined with AddaVAX elicited highest neutralizing antibody titers against H7N7 virus compared with other groups (Fig. 2B). Additionally, vaccination with 0.5 μg AddaVAX-adjuvanted H7N7 vaccines was shown also EGFR assay to induce significant amounts of cross reactive H7N9-specific HAI and substantial viral neutralization titers (Fig. 2C and D). Taken together, the squalene-based adjuvant has shown great potential to be an effective immune modulator to improve the immunogenicity of H7-subtype influenza virus vaccines. Following the observations with H7N7 vaccine either in split or whole virus format elicited different levels of immune response depending on adjuvants reported in the section above, we investigated many the specific anti-HA immunoglobulin (IgG) induced by H7N9 vaccination in different formats. The ELISA results showed that all groups of mice vaccinated with H7N9 vaccines exhibited a

significant response of IgG antibodies against H7 protein (Fig. 3A). The mice immunized with 0.5 μg or above of AddaVAX-adjuvanted H7N9 split virus antigen resulted in higher ELISA mean titers of 1:40,899–1:56,430 (Fig. 3A, lanes C, I, and O) than AddaVAX-adjuvanted H7N9 whole virus antigen (1:12,500–1:56,430) (lanes F, L, and R). Unlike the observations with H7N7 antigens, the same dosages of both H7N9 vaccine antigens with Al(OH)3 (Fig. 3A, lanes B, E, H, K, N, and Q) or without adjuvants (Fig. 3A, lanes A, D, G, J, M, and P) also induced ELISA mean titers ranging from 1:5,300–1:62,500. Again, it suggested that AddaVAX-adjuvanted H7N9 vaccine may be a superior formulation to induce robust humoral immune response specific to HA of H7N9 virus than Al(OH)3-adjuvantation or without adjuvant.