A novel emulsion adjuvant increases the immunogenic responses and protective efficacy of an inactivated influenza vaccine in BALB/c mice.

OBJECTIVE The research of adjuvants is a hot topic in vaccinology. In this paper, we were seeking a concise method to produce a stable and effective emulsion adjuvant. METHODS A novel emulsion [Well Adjuvant Formulation 3 (WAF3)] was produced by adding additional glycerol and using a timely cooling process. Surface morphology analysis of the novel emulsion was performed by atomic force microscopy. Animal experimentation was used to evaluate the efficacy of the novel adjuvant. RESULTS Surface morphology analysis of the novel emulsion showed a homogeneous distribution of the antigen protein. We also confirmed the morphological changes of the WAF3-carrying antigen. The WAF3-adjuvanted vaccine engendered higher antibody responses 128-fold compared to that of a naked antigen. Furthermore, in the presence of the WAF3 adjuvant, the influenza virus antigen was able to reduce the titer disparities of IgG2a and IgG1. The WAF3-adjuvanted influenza vaccine was able to provide full protection and alleviation of infective symptoms as other clinically adjuvanted vaccines. CONCLUSION The WAF3 adjuvant is a promising candidate to be further investigated in the development of emulsion adjuvants.