Zoonotic infections infections in livestock and the risk to public health - Poster Abstract

Verotoxin-1 from E.coli O157 binds to bovine intestine and kidney cells

E Hoey et al

Cattle have been implicated as an important reservoir of verotoxin-(VT) producing Escherichia coli (EHEC, enterohemorrhagic E.coli ) and in particular E.coli 0157. EHEC can cause haemorrhagic colitis (HC), haemolytic uremic syndrome (HUS) and thrombocytopaenia purpura (TTP) in humans. Infection in cattle is mainly asymptomatic although detectable levels of both VT-1 and VT-2 are excreted.

Investigations have been initiated into verotoxin-globotriaosyl ceramide (Gb3) binding, receptor distribution and heterogeneity of the ceramide fatty acid chain length of the Gb3 receptor in cattle.

Binding studies of VT-1 to frozen tissue sections of the colon and caecum, derived from both one month and ten month old cattle, demonstrated toxin binding sites in immature proliferating crypt cells adjacent to the sub-mucosa. No binding was detected in the endothelium of either of these tissues. In the kidney of both age groups of cattle, VT-1 primarily bound to the distal convoluted tubules and collecting ducts with a complete absence of binding in the glomeruli.

Glycolipids were extracted and the receptors for VT-1 identified by thin layer chromatographic overlay assay. The predominant isoforms of Gb3 present in cattle were shown to be absent in the corresponding human tissues.

The age-related incidence of HUS in humans correlates with the expression of Gb3 within the renal glomerulus, thus toxin receptor distribution plays a central role in the induction of pathology. Furthermore the isoform of Gb3 synthesised may be highly relevant to determining VT sensitivity. The difference in receptor isoform and distribution may provide an explanation for the absence of the disease in cattle. The consequence of VT binding to proliferating crypt cells remains to be examined.

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