Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 10 6 2019 02 09 361 370 EN Pegah Almasian Department of Genetics and Biotechnology, School of Biological Sciences, Varamin-Pishva Branch, Islamic Azad University, Varamin, Iran Jafar Amani Applied Microbiology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran Fahimeh Baghban Arani Department of Genetics and Biotechnology, School of Biological Sciences, Varamin-Pishva Branch, Islamic Azad University, Varamin, Iran Shahram Nazarian Department of Biology, Faculty of Sciences, Imam Hossein University, Tehran, Iran Rouhollah Kazemi Department of Agricultural Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran Niloufar Mirzaee Tabrizi Department of Genetics and Biotechnology, School of Biological Sciences, Varamin-Pishva Branch, Islamic Azad University, Varamin, Iran 2018 01 02 2018 08 16 Background and Objectives: Escherichia coli O157:H7 is one of the most important food pathogens that produces colitis and bloody urine in humans. The Stx2B subunit is considered as one of the candidates for vaccine due to its immunogenic and adjuvant properties. Designing a mucosal vaccine using nanoparticles for protecting the antigen against degradation and controlling the release of antigen are important. The objective of the current study was to prepare nanoparticles containing the Stx2B subunit of E. coli O157:H7 and evaluation of its immunogenicity in the mouse model. Materials and Methods: E. coli BL21 DE3 and pET28a-stxB were used for expression of the stx2b gene. After inducing gene expression, purification of the Stx2b protein was performed. Then, chitosan nanoparticle containing recombinant Stx2B was prepared and administered to BALB/c mice. IgA and IgG titers in serum and IgA titers in feces of immunized and control mice were evaluated by the ELISA method. Results: After expression and purification of the Stx2B recombinant protein, an expected band of 13 kDa was observed on the SDS-PAGE gel and confirmed by Western Blot analysis. The size of the nanoparticle containing Stx2B was 290 nm. In the immunized mice, IgG and IgA titers were significantly increased. The immunized mice were challenged against E. coli O157:H7 Stx+ and the shedding analysis showed that colonization of bacteria in the intestinal tract decreased. Conclusion: Oral administration of nanoparticles containing Stx2B as a candidate for the vaccine can induce a systemic and mucosal immune response against Stx2 toxin and can provide acceptable protection. https://ijm.tums.ac.ir/index.php/ijm/article/view/1604 https://ijm.tums.ac.ir/index.php/ijm/article/download/1604/1100