Helicobacter pylori: molecular evolution of a bacterial quasi-species

Curr Opin Microbiol. 1998 Feb;1(1):96-102. doi: 10.1016/s1369-5274(98)80148-3.


Helicobacter pylori persists chronically within individuals and as they spread the mutating bacteria migrate with them. The continuous selection and microevolution generates a population of closely related but different bacteria that behave like a quasi-species. Within this heterogeneity, H. pylori strains fall into distinct types, into the virulent (type I) and less virulent (type II) strains, based on the presence of a pathogenicity island (cag) that encodes a specialized secretion machinery. We propose that during chronic infection a dynamic equilibrium between bacteria expressing a disparate degree of virulence is established, and that diverse forms prevail at different times.

Publication types

  • Review

MeSH terms

  • Animals
  • Evolution, Molecular*
  • Genes, Bacterial
  • Helicobacter pylori / genetics*
  • Helicobacter pylori / pathogenicity*
  • Humans
  • Mice
  • Virulence / genetics