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Curr Opin Microbiol. 1998 Feb;1(1):96-102.

Helicobacter pylori: molecular evolution of a bacterial quasi-species.

Author information

1
Department of Molecular Biology, Immunobiological Research Institute ofSiena (IRIS), Chiron Vaccines, Via Fiorentina 1, 53100 Siena, Italy. covacci@iris02.biocine.it

Abstract

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.

PMID:
10066468
[Indexed for MEDLINE]

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