pseudomonas aeruginosa pao-1 lipopolysaccharide-diphtheria toxoid conjugate vaccine: preparation, characterization and immunogenicity

Background: treatment of pseudomonas aeruginosa pao-1 infections through immunological means has been proved to be efficient and protective. objectives: the purpose of this study was to produce a conjugate vaccine composed of detoxified lipopolysaccharide (d-lps) p. aeruginosa and diphtheria toxoid (dt). materials and methods: firstly, lps was purified and characterized from p. aeruginosa pao1 and then detoxified. d-lps was covalently coupled to dt as a carrier protein via amidation method with adipic acid dihydrazide (adh) as a spacer molecule and 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide (edac) as a linker. the molar ratio of lps to dt in the prepared conjugate was 3:1. the immunogenicity of d-lps-dt conjugate vaccine in mice model was evaluated as well. results: the conjugate was devoid of endotoxin activity and 0.125 u/ml of d-lps was acceptable for immunization. d-lps-dt conjugate was nonpyrogenic for rabbits and nontoxic for mice. mice immunization with d-lps-dt conjugate vaccine elicited the fourfold higher igg antibody compared to d-lps. anti-lps igg antibody was predominantly igg1 subclass and then igg3, igg2a and igg2b, respectively. conclusions: vaccine based on the conjugation of p. aeruginosa pao-1 lps with dt increased anti-lps antibodies and had a significant potential to protect against pseudomonas infections.