The Clinical Significance Of Campylobacter Jejuni Gale Gene Mutants

Objectiv: To explore galE mutants of Campylobacter jejuni (CJ) whether have a changed lipooligosaccharide (LOS) structure and changed antigenicity. Methods: With parental strains (CJ HB9313, HS:19) and galE mutants following study was performed: â‘  LOS from parental strains and galE mutants were isolated and purified by the hot phenol-water technique; â‘¡ Male New England white rabbits were used to raise rabbit anti-CJ HB9313 LOS polyclonal sera by systematically immunized with purified CJ HB9313 LOS; â‘¢ The purified LOS preparations from parental strains and galE mutants were resolved by Tricine SDS polyacrylamide gel electrophoresis (PAGE), analyzed by silver staining and Western blotting ( rabbit anti-CJ HB9313 LOS polyclonal sera serving as the first antibody and goat anti-rabbit IgG conjugated with peroxidase serving as the second antibody), and were tested for reaction with the ganglioside-binding ligands of cholera toxin (cholera toxin B subunit conjugated with peroxidase serving as the ligand of ganglioside GM1).Results: â‘  Examination of silver-stained gels revealed that LOS from galE mutants was of increased mobility relative to the LOS from parental strains, and the former expressed a molecule of 4.5 kDa whereas the latter had a LOS molecule of around 5.5 kDa. These results indicated that the LOS expressed by galE mutants was truncated and loss of sugar residues. â‘¡ Examination of Western blotting showed that the LOS expressed by galE mutants, no longer reacted with antiserum raised against the LOS expressed by parental strains and removed epitopes that react with the antiserum. â‘¢ The result of ligand blotting revealed that cholera toxin specially bound to the LOS of parental strains , however, LOS from galE mutants failed to bind cholera toxin, which was consistent with the loss of sugar residues and ganglioside-like structures from outer core part of the LOS.Conclusions: galE mutants lose sugar residues and ganglioside-like structures from outer core part of the LOS and show a changed antigenicity, may become a safe, live-vaccine without the possibility of inducing an immune response to host gangliosides.