Cellular and Molecular Life Sciences CMLS

, Volume 56, Issue 9–10, pp 735–741 | Cite as

Evolution of virulence factors in Shiga-toxin-producing Escherichia coli

  • P. Boerlin


The major demonstrated or putative virulence factors of Shiga-toxin-producing Escherichia coli (STEC) are the Shiga toxins, products of the locus of enterocyte effacement, and products encoded by the EHEC-hemolysin plasmid. Molecular analysis shows that STEC acquired the majority of these virulence factors by horizontal transfer of genetic material. In the case of Shiga toxins, the phages encoding them are probably responsible for this transfer. For the locus of enterocyte effacement, however, it is not clear how often this transfer took place and which parts of the locus were involved in this transfer. The large EHEC-hemolysin plasmid is clearly a mosaic structure, which arose from multiple recombination events with foreign DNA. Two lineages of this plasmid can be distinguished, one of which is associated with chromosomally encoded virulence factors. Despite the wealth of information available, further comparative studies are needed to decipher definitively the evolution of virulence in STEC.

Key words. STEC; SLTEC; VTEC; Shiga toxin; locus of enterocyte effacement; hemolysin; plasmid; evolution; virulence. 


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Copyright information

© Birkhäuser Verlag Basel, 1999

Authors and Affiliations

  • P. Boerlin
    • 1
  1. 1.Institute for Veterinary Bacteriology, University of Bern, Länggass-Strasse 122, CH-3012 Bern (Switzerland), Fax +41 31 631-2634, e-mail: patrick.boerlin@vbi.unibe.chCH

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