icsB: a Shigella flexneri virulence gene necessary for the lysis of protrusions during intercellular spread

Mol Microbiol. 1992 Jun;6(12):1605-16. doi: 10.1111/j.1365-2958.1992.tb00885.x.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / isolation & purification
  • Bacteriolysis / genetics*
  • Base Sequence
  • Extracellular Space / microbiology
  • Gene Expression Regulation, Bacterial / physiology
  • Genes, Bacterial / genetics
  • Genes, Bacterial / physiology*
  • HeLa Cells / microbiology
  • Humans
  • Microscopy, Electron
  • Molecular Sequence Data
  • Mutation
  • Open Reading Frames / physiology
  • Recombinant Fusion Proteins / isolation & purification
  • Shigella flexneri / genetics*
  • Shigella flexneri / pathogenicity
  • Shigella flexneri / ultrastructure
  • Temperature
  • Virulence / genetics
  • Virulence / physiology


  • Bacterial Proteins
  • Recombinant Fusion Proteins

Associated data

  • GENBANK/M86530