Background and purpose: Shigella species cause shigellosis in humans. Considering the high frequency of illness and antibiotic resistance, development of an effective immunogen against bacteria is a major goal. Invasion Plasmid Antigen such as IpaD and IpaC are the major bacterial virulence agents of Shigella. Encapsulation of antigens in particular carriers such as chitosanic  nanogels, not only protects them from degradation in environmental elements but also provides the effective concentrations of antigens in targets, hence increasing bioactivity. The aim of this study was to investigate the immunogenic properties of IpaC protein encapsulated in chitosanic nanogels.

Materials and methods: The protein was expressed in E.coli and purified by affinity chromatography. Chitosan nanogels were prepared by ionic gelation method using tripolyphosphate (TPP) as a crosslinking agent. The nanogels were loaded with IpaC and their structures were characterized by SEM and DLS. Encapsulated protein was introduced in guinea pigs by oral and parenteral routes. Antibody titers were determined by ELISA. Animals were challenged By Sereny test with wild-type S. flexneri.

Results: Expression of recombinant protein in E.coli led to the production of IpaC with 60 kDa molecular weight. Loading efficiency of nanogel was 98% after 48h of incubation. The average particle size was 418 nm. Immunization of mice induced serum antibody response.

Conclusion: The productivity of encapsulated protein via oral route was better than parenteral route.