Synthesis, characterization and immunological properties of Escherichia coli 0157:H7 lipopolysaccharide- diphtheria toxoid conjugate vaccine

• Main Authors: Shadi Rokhsartalab-Azar, Reza Shapouri, Mehdi Rahnema, Faezeh Najafzadeh, Anvarsadat Kianmehr
• Format: Article
• Language: English
• Published: Tehran University of Medical Sciences 2015-11-01
• Series: Iranian Journal of Microbiology
• Subjects: Escherichia coli O157; H7; Conjugate vaccine; Lipopolysaccharide (LPS); Diphtheria toxoid (DT)
• Online Access: https://ijm.tums.ac.ir/index.php/ijm/article/view/815

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.