Optimally Fabricated Chitosan Particles Containing Ovalbumin Induced Cellular and Humoral Immunity in Immunized Mice

Subunit vaccines have been developed as promising vaccines with safety. However, subunit vaccines have difficulties in commercialization due to low efficiencies of delivery and immune response. As a result, studies of adjuvants that improve the immune-inducing ability of vaccines have been conducted globally. Aluminum salts (alum) have been extensively used as vaccine adjuvants, but they cannot induce potent cellular immunity. In this study, chitosan particles were fabricated by the precipitation-coacervation method on four different conditions. Ovalbumin (OVA), as a model antigen, was encapsulated in chitosan particles. The optimized fabrication conditions of chitosan particles were 8 mL/min drop rate of sodium sulfate and 0.5 mg/mL chitosan concentration in a sonication bath. Properties of the optimized chitosan particle were about 300 nm diameter, 0.1 polydispersity index, 16.2 mV zeta potential, and 90% loading efficiency. Chitosan particle-containing OVA showed 76% uptake efficiency by mouse macrophage cells and suitable cell viability. Immunization of mice by chitosan particles exhibited IgG1 titer and Interleukin-4 production of a similar level with the alum. Moreover, chitosan particles showed significantly enhanced IgG2 titer and Interferon-gamma production related to Th1-mediated cellular immune response. These results indicated that chitosan particles could be expected to be a promising adjuvant inducing cellular and humoral immunity for subunit vaccine delivery.