Chitosan hydrochloride salt stabilized emulsion as vaccine adjuvant.

Traditional emulsion adjuvants are stabilized by non-ionic surfactants and promote high humoral immunity. However, because of their electroneutrality, they cannot effectively carry negatively charged antigens and enter the cell to elicit cellular immunity. To overcome this problem, we developed an emulsion using chitosan hydrochloride salt (CSCL) as stabilizer. After optimization, CSCL was successfully adsorbed on the surface of the emulsion (CPSE), and stabilized for two months. CPSE could effectively loading the antigen and slow down the rate of the antigen release. We evaluated the effectiveness of CPSE through intramuscular immunization in mice after cytotoxicity assay proved its safety. CPSE not only induced strong antibody-mediated immune responses, but also generated memory T cells in the spleen as a marker of adaptive immunity. Importantly, CPSE showed advantages over the conventional vaccine formulations in promoting IFN-γ secretion. CPSE may act as a promising candidate to enhance the efficacy of vaccines with acceptable biocompatibility and safety.