Escherichia coli O157:H7 is one of the most important pathogens which create hemorrhagic colitis and hemolytic uremic syndrome in human. It is one of the most prevalent causes of diarrhea leading to death of many people every year. The first diagnosed gene in the locus of enterocyte effacement pathogenicity island is eae gene. The product of this gene is a binding protein called intimin belonging to the group of external membrane proteins regarded as a good stimulants of the immune system. Chitosan with its lipophilic property is an environmentally friendly agent able to return to the environment.

Intimin recombinant protein was expressed in pET28a vector with eae gene and purification was performed using Ni-NTA and finally the recombinant protein was approved through western blotting. This protein was encapsulated using chitosan nanoparticles and the size of nanoparticles was measured by Zetasizer. Intimin encapsulated was prescribed for three sessions among three groups of oral, injection, and oral-injection using Chitosan nanoparticles. Challenge was performed for all three groups with 10⁸ E. coli O157:H7 bacteria.

Intimin produced by chitosan nanoparticles improves immunological responses through the adjuvant nature of chitosan nanoparticles. Chitosan may be used as a carrier for transportation of the prescribed vaccine. Among the mice, encapsulated intimin could be able to provide suitable titers of IgG and IgA by the aid of chitosan nanoparticles. Results of mice challenge showed that decreased the bacterial shedding significantly.

Results showed that the chitosan nanovaccine with intimin protein may be used as a suitable candidate vaccine against E. coli O157:H7.