title: HeLa cell invasion by a strain of enteropathogenic Escherichia coli that lacks the O-antigenic polysaccharide.
abstract: The interaction with HeLa cells of an enteropathogenic Escherichia coli (EPEC) strain and its plasmid-cured derivative strain was examined. An O111:NM EPEC strain B171 harbours a 54 megadalton plasmid (pYR111) necessary for the expression of both localized adherence (LA) to HeLa cells and the O-repeating side chain of the lipopolysaccharide. Under light microscopy, the plasmid-cured derivative strain B171-4 was observed to interact with HeLa cells in a pattern distinct from LA. Transmission electron microscopy showed that the bacteria were internalized by HeLa cells. In contrast, strain B171 induced pedestal-like projections and invaginations of the plasma membrane, but was never completely internalized. A quantitative assay to determine the number of internalized bacteria revealed that strain B171-4 was internalized at levels 30-70-fold higher than those of avirulent E. coli strains. Cytochalasin B reduced the levels of internalization of both strain B171-4 and an enteroinvasive E. coli strain (E11), but did not affect LA by strain B171. These results suggest that EPEC strain B171 may carry a specific chromosomally determined surface factor needed to initiate internalization by HeLa cells. However, a plasmid-determined factor alters the nature of this interaction; the combined effects of the chromosomal and plasmid determinants lead to the characteristic attachment of the bacteria in clusters on the surface of the eukaryotic cell.
authors.affiliation: Department of Microbiology, Stanford University, California 94305.
authors.forename: L W
authors.initials: LW
authors.lastname: Riley
authors.forename: L N
authors.initials: LN
authors.lastname: Junio
authors.forename: G K
authors.initials: GK
authors.lastname: Schoolnik
mesh_terms: D000942:Antigens, Bacterial / Q000235:genetics*; D001422:Bacterial Adhesion / Q000187:drug effects; D002448:Cell Adhesion / Q000187:drug effects; D003571:Cytochalasin B / Q000494:pharmacology; D004926:Escherichia coli / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D005798:Genes, Bacterial; D006367:HeLa Cells / Q000382:microbiology / Q000648:ultrastructure; D006801:Humans; D008854:Microscopy, Electron; D019081:O Antigens; D010957:Plasmids; D011135:Polysaccharides, Bacterial / Q000378:metabolism*
chemical_list: D000942:Antigens, Bacterial; D019081:O Antigens; D011135:Polysaccharides, Bacterial; D003571:Cytochalasin B