title: Plasmid-encoded expression of lipopolysaccharide O-antigenic polysaccharide in enteropathogenic Escherichia coli.
abstract: The role of a plasmid in the virulence activity of an enteropathogenic Escherichia coli (EPEC) strain belonging to serotype 0111:NM was examined. EPEC strain B171, which is resistant to chloramphenicol, streptomycin, sulfathiazole, and tetracycline, harbors a 54-megadalton plasmid, pYR111, and exhibits localized adherence (LA) with HeLa cells. Curing the plasmid yielded strain B171-4, which had lost the ability to exhibit LA, resistance to the antibiotics, and the lipopolysaccharide (LPS) O-antigenic polysaccharide. To confirm that these phenotypic characteristics were specified by pYR111, the plasmid was transferred by conjugation into a nalidixic acid-resistant strain of E. coli HB101. LA and antimicrobial resistance were expressed in most of the transconjugants examined. The O-polysaccharide side chains, antigenically reactive with O111-specific antiserum, were also expressed by the transconjugants. Although EPEC plasmids coding for both drug resistance and LA have been described, an EPEC plasmid encoding the expression of an LPS O antigen has not been previously reported. Similar findings described for some Shigella and Salmonella strains suggest that plasmid-encoded modification of the LPS in some enteric bacterial species may be more common than previously recognized and may contribute to the characteristic virulence activity of the organism.
authors.forename: L W
authors.initials: LW
authors.lastname: Riley
authors.forename: L N
authors.initials: LN
authors.lastname: Junio
authors.forename: L B
authors.initials: LB
authors.lastname: Libaek
authors.forename: G K
authors.initials: GK
authors.lastname: Schoolnik
mesh_terms: D000942:Antigens, Bacterial / Q000235:genetics*; D001422:Bacterial Adhesion; D003227:Conjugation, Genetic; D003967:Diarrhea / Q000382:microbiology*; D004926:Escherichia coli / Q000235:genetics* / Q000276:immunology / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000382:microbiology; D005798:Genes, Bacterial; D010641:Phenotype; D010957:Plasmids; D011135:Polysaccharides, Bacterial / Q000235:genetics*
chemical_list: D000942:Antigens, Bacterial; D011135:Polysaccharides, Bacterial