title: The Edwardsiella ictaluri O polysaccharide biosynthesis gene cluster and the role of O polysaccharide in resistance to normal catfish serum and catfish neutrophils.
abstract: Edwardsiella ictaluri, the causative agent of enteric septicaemia of catfish (ESC), expresses long O polysaccharide (OPS) chains on its surface. The authors previously reported the construction of an isogenic Ed. ictaluri OPS mutant strain and demonstrated that this strain is avirulent in channel catfish. This paper reports the cloning of the Ed. ictaluri OPS biosynthesis gene cluster and identification of the mutated gene in the OPS-negative strain. The sequenced region contains eight complete ORFs and one incomplete ORF encoding LPS biosynthesis enzymes. The mutated gene (designated wbiT) was similar to other bacterial galactose-4-epimerases. Glycosyl composition analysis indicated that wild-type Ed. ictaluri OPS contains higher amounts of galactose and N-acetylgalactosamine than the OPS mutant strain, which correlated well with predicted functions of the genes identified in the OPS biosynthesis cluster. The OPS mutant had a relatively small, but significant, decrease in its ability to survive in normal catfish serum compared to wild-type Ed. ictaluri, but it retained the ability to resist killing by catfish neutrophils.
authors.affiliation: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762-6100, USA.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Lawrence
authors.affiliation: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762-6100, USA.
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Banes
authors.affiliation: Complex Carbohydrate Research Center, 220 Riverbend Road, Athens, GA 30602-4712, USA.
authors.forename: Parastoo
authors.initials: P
authors.lastname: Azadi
authors.affiliation: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762-6100, USA.
authors.forename: Brenda Y
authors.initials: BY
authors.lastname: Reeks
mesh_terms: D000818:Animals; D001483:Base Sequence; D001770:Blood Bactericidal Activity; D002397:Catfishes / Q000097:blood / Q000276:immunology* / Q000382:microbiology*; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics; D020610:Edwardsiella ictaluri / Q000235:genetics* / Q000276:immunology / Q000472:pathogenicity*; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D016695:Glycosyltransferases / Q000235:genetics; D008969:Molecular Sequence Data; D005810:Multigene Family; D009154:Mutation; D009504:Neutrophils / Q000276:immunology / Q000382:microbiology; D019081:O Antigens / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D016366:Open Reading Frames; D011112:Polymyxin B / Q000494:pharmacology; D014534:UDPglucose 4-Epimerase / Q000235:genetics
chemical_list: D004269:DNA, Bacterial; D019081:O Antigens; D016695:Glycosyltransferases; D014534:UDPglucose 4-Epimerase; C020551:galactose epimerase; D011112:Polymyxin B