Comparative Evaluation of Mx and Alum as Bio and Conventional Adjuvants in Inducing Immune Responses by Influenza DNA Vaccine

Background Objective: DNA vaccines as a new generation of vaccines require adjuvant to improve vaccine immunogenicity; adjuvants can also increase the DNA vaccine efficacy. In this study, the effects of the host’s interferon-inducible Mx protein as bio adjuvant and conventional alum adjuvant were evaluated. Materials Methods: The BALB/c mice were immunized by different prime-boost strategies of the alum and Mx adjuvanted-HA2 DNA vaccine; they were challenged with the specific influenza virus. The potency and safety were evaluated. Humoral immune response was assayed by haemagglutination and virus neutralization tests. The induction of cell-mediated immune responses was determined using an MTT assay. The safety of vaccine regarding side effects occurrence was assessed by observation and histopathologic evaluation. Results: Mx as a host defense peptide was able to increase the immune response against influenza better than alum adjuvant (p 0.01). By HA2 and Mx in prime and boost strategy, the highest level of specific antibodies developed; they are capable of inducing cell-mediated immune responses. Results indicated that Mx in the DNA vaccine could induce stronger immune responses without any side effects; but alum had some local and general reactions. Conclusion: The Mx could effectively enhance immune responses; it has the potential to enhance the vaccine immunogenicity.