Authors: Richa Jha, Shantanu Tamuly, Mumtesh Kumar Saxena
Adjuvant play important role in enhancing the immunogenicity of a vaccine. Due to induction of inflammatory reactions and irritation at the site of administration, the commonly used adjuvants are subjected to limitations. Therefore, there is an increased necessity for new vaccine adjuvant systems for better antigen delivery and prolonged protection. Calcium phosphate nanoparticles have been considered as potential adjuvants due to their penetrability and ability to stimulate immunoregulatory reactions. In the present study, Calcium phosphate nanoparticles were characterized as an adjuvant for a potentially weak recombinant antigen, Outer membrane protein (OmpC) against Salmonellosis. The nanoparticles loaded with Recombinant OmpC protein with an entrapment efficiency of 20.64% and loading capacity of 300μg/mg were used in the study. Recombinant OmpC protein of Salmonella Typhimurium was used for immunization in murine model and challenge studies were compared between two adjuvants, Calcium phosphate nanoparticle and Quillaja saponin. Although, the humoral response induced by CaPO4 nanoparticles was not significant, the results of challenge studies concluded that CaPO4 nanoparticles provide better protection against Salmonella as compared to saponin adjuvant. It may me deduced that the induction of strong cell mediated immunoregulatory response led to a significantly positive protection during challenge. Moreover, further studies to unravel the exact mechanism of action of CaPO4 nanoparticles are necessary for its commercial application as an adjuvant system especially for weak antigens against endogenous pathogens.
Keywords: CaPO, Nanoparticles, vaccines, adjuvants, OmpC, Xray Diffraction