Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 7 3 2015 11 25 150 155 EN Shadi Rokhsartalab-Azar Young Researchers and Elite Club, Urmia Branch, Islamic Azad University, Urmia, IR Iran. Reza Shapouri Department of Microbiology, Zanjan Branch, Islamic Azad University, Zanjan, IR Iran. Mehdi Rahnema Biologic Research Center, Zanjan Branch, Islamic Azad University, Zanjan, IR Iran. Faezeh Najafzadeh Young Researchers Club, Bonab Branch, Islamic Azad University, Bonab, IR Iran. Anvarsadat Kianmehr Department of Medical iotechnology, School of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, IR Iran. 2015 11 24 Background and Objective: Escherichia coli O157:H7, an emerging pathogen, causes severe enteritis and the extraintestinal complication of hemolytic-uremic syndrome. The goal of this study was to evaluate the conjugate of E. coli O157: H7 lipopolysaccharide (LPS) with diphtheria toxoid (DT) as a candidate vaccine in mice model. Material and Methods: LPS from E. coli O157:H7 was extracted by hot phenol method and then detoxified. Purified LPS was coupled to DT with adipic acid dihydrazide (ADH) as a spacer and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) as a linker. The coupling molar ratio of LPS to DT was 3:1. Clinical evaluation of E. coli O157:H7 LPS-DT conjugate was also performed. Results: The conjugate was devoid of endotoxin activity and indicated 0.125 U/ml of D-LPS. Mice immunization with D-LPS DT conjugate elicited fourfold higher IgG antibody in comparison to D-LPS. Also, in vivo protection of mice with conjugate provided high protection against the LD50 of E. coli O157:H7, which indicated a good correlation with the IgG titer. Conclusion: Our results showed that the suggested vaccine composed of E. coli O157:H7 LPS and DT had a significant potential to protect against E. coli infections. https://ijm.tums.ac.ir/index.php/ijm/article/view/815 https://ijm.tums.ac.ir/index.php/ijm/article/download/815/500