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

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.  

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.

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.

The Mx could effectively enhance immune responses; it has the potential to enhance the vaccine immunogenicity.