Immune-stimulating potential of cell envelope proteins from Vibrio cholerae associated to chitosan microparticles: an in vitro study.

Context: Cholera is a severe diarrheal disease that remains an important cause of illness and death in many parts of the world.

Objective: This study has been designed to check the immune-stimulating potential of antigens in their native and associated form as chitosan microparticles in vitro.

Material and methods: Chitosan microparticles were prepared by the ionic gelation technique. The cell envelope proteins (CEPs) isolated from Vibrio cholerae were loaded as antigenic material. The prepared microparticles were characterized for their morphology, loading efficiency, particle size, and zeta potential.

Results: The average particle size of CEPs-loaded chitosan microparticles was 2.24 µm and the zeta potential of loaded microparticles was less than blank microparticles. The in vitro release studies of CEPs from CEPs-loaded chitosan microparticles exhibited slow and extended release over a period of time. The higher release of cytokine profile, including interferon γ (IFN-γ), tumor necrosis factor α (TNF-α), and interlukin-6 (IL-6), was observed for CEPs-loaded chitosan microparticles in comparison to CEPs as native antigen.

Discussion: The particle size of microparticles was within the range for phagocytosis by macropahges, which affects the immunogenicity. The decrease in zeta potential from blank to loaded microparticles further confirms the loading of antigen. The slow and extended release of CEPs provides continuous stimulus of antigen for a longer period of time. The cytokine profiling has shown the advantage of loaded microparticles over native antigen.

Conclusion: The in vitro release studies and cytokine profiling strongly suggested that CEPs-associated chitosan microparticles could be a potential candidate for oral vaccination against Vibrio cholerae.