ABSTRACT
Objective To investigate the specific pathogenesis of O-antigen polysaccharide(OPS) which is a subunit component of lipopolysaccharide(LPS) from enteroinvasive Escherichia coli. Methods The OPS was extracted and purified from Escherichia coli O29(enteroinvasive E.coli) strain. Effects of OPS, contrasted with the whole LPS molecule, were observed by in vitro experiments (HeLa cell culture) and in vivo experiments (rabbit ileal loop assay). Results It was revealed that the purified EIEC OPS alone cause cytopathic effect to HeLa cell, and that the OPS caused mucosal hemorrhage, but no fluid accumulation in ileal loop of rabbits. The scanning electron microscope and transmission electron microscope demonstrated the fine structures of cytopathic HeLa cell were damaged. Conclusion Escherichia coli O29 OPS might be one of the factors causing diarrhea and its mechanism was different from endotoxin reaction of LPS. Escherichia coli O29(pathogen) OPS showed a marked serious toxicity as compared with Escherichia coli HB101(nonpathogen) OPS.