title: icsB: a Shigella flexneri virulence gene necessary for the lysis of protrusions during intercellular spread.
abstract: Shigella flexneri causes bacillary dysentery by invading epithelial cells of the colonic mucosa. We have characterized the icsB gene which is located on the virulence plasmid pWR100. After inactivation of icsB, the mutant strain remained invasive, but formed abnormally small plaques on HeLa cell monolayers, colonized only the peripheral cells of Caco-2 islets, and was unable to provoke a keratoconjunctivitis in guinea-pigs. Examination of infected HeLa cells showed that the icsB mutant was able to lyse the phagocytic vacuole and to form protrusions at the surface of infected cells, but, unlike the wild type, remained trapped in protrusions surrounded by two membranes. These results indicate that IcsB is involved in the lysis of the protrusions, a step necessary for intercellular spread.
authors.affiliation: Unité de Pathogénie Microbienne Moléculaire, Unité INSERM 199, Institut Pasteur, Paris, France.
authors.forename: A
authors.initials: A
authors.lastname: Allaoui
authors.forename: J
authors.initials: J
authors.lastname: Mounier
authors.forename: M C
authors.initials: MC
authors.lastname: Prévost
authors.forename: P J
authors.initials: PJ
authors.lastname: Sansonetti
authors.forename: C
authors.initials: C
authors.lastname: Parsot
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000302:isolation & purification; D001433:Bacteriolysis / Q000235:genetics*; D001483:Base Sequence; D005110:Extracellular Space / Q000382:microbiology; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D005798:Genes, Bacterial / Q000235:genetics / Q000502:physiology*; D006367:HeLa Cells / Q000382:microbiology; D006801:Humans; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009154:Mutation; D016366:Open Reading Frames / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification; D012763:Shigella flexneri / Q000235:genetics* / Q000472:pathogenicity / Q000648:ultrastructure; D013696:Temperature; D014774:Virulence / Q000235:genetics / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; D011993:Recombinant Fusion Proteins