Enterohaemorrhagic Escherichia coli virulence genes: progress towardstheir identification and prospects for control in food-producing animals.
2006
Stevens, M. P.
Enterohaemorrhagic <i>Escherichia coli</i> (EHEC) comprise a subset of Shiga toxin (Verocytotoxin)- producing <i>E. coli</i> associated with acute gastroenteritis in humans. Infections are frequently caused by direct or indirect contact with ruminant faeces and may be complicated by haemorrhagic colitis and severe renal and neurological sequelae. Broadly cross-protective vaccines or treatments for control of EHEC in reservoir hosts do not yet exist and the molecular mechanisms by which they persist in the intestines of ruminants are incompletely understood. Targeted and genome-wide mutagenesis of EHEC has revealed a key role in colonization for a Type III secretion system which mediates the formation of 'attaching and effacing' lesions on intestinal epithelia by injection of bacterial proteins into enterocytes. Other conserved and serotype-specific colonization factors exist, including fimbriae, adhesins and cytotoxins. Variation in the repertoire, sequence or expression of such factors may explain the differential virulence of EHEC serogroups and provide genetic markers for risk analysis. This review details progress towards the identification of EHEC virulence genes and application of this knowledge to control EHEC in food-producing animals.
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