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Identification of Factors Mediating Colonisation of Cattle by Enterohaemorrhagic Escherichia coli - OZ0707

Description
Escherichia coli O157:H7 is an emerging zoonotic pathogen of worldwide importance. Meat products derived from cattle in which intestinal colonisation occur in the absence of overt disease are considered to be a major source of infection. Limitations to the control of the disease arise because of inadequate information on the virulence mechanisms of the causation bacteria.

The aim of this project is to identify bacterial and host factors involved in colonisation of the bovine intestine. Calves, bovine ligated intestinal loops and bovine intestinal organ cultures will be infected with wild-type and defined mutants of different strains, and bacterial and host factors involved in colonisation, adhesion, lesion formation and diarrhoea production will be identified.

This approach will provide insight into the molecular basis of colonisation and disease processes and may identify bacterial proteins which could be incorporated into sub-unit or vector-based vaccines. It could also lead to the development of novel biological control methods not based on vaccination. The strategic aim is to provide information which can be used to reduce Escherichia coli in cattle and prevent their transmission to humans.
Objective
01 31/07/2002 Sheep locialisation studies with EHEC 0157 marked with GFP. The E. coli 0157 (Stx-) strain NCTC12900 will be marked by constitutive expression of GFP using a ribosomal RNA promoter and established prokaryotic translational signals. The construct will be placed at lac using standard allelic exchange methods employed within the ZAP lab for construction of both GFP and LacZ fusions into this strain at this locus. The strain will be used for locialisation studies within the gastrointestinal tract of orally-inoculated sheep.

02 31/09/2003 Sheep persistence studies with EHEC 0157 wild-types and isogenic mutants. To test long polar fimbriae, flagella, intimin and EFA mutants of two E. coli 0157 strains for their persistence in the sheep model developed at VLA. The role of LPF, flagella, intimin and EFA will be investigated by competitive index using dual strain (wild type vs. mutant) oral dosing.

03 31/03/2004 Assay EHEC 0157 wild-types and isogenic mutants in the ligated gut loop. A kep aim is to understand the interation between EHEC 0157 wild-types and their isogenic mutants at the level of the epithelium. Ligated gut loops (and accompanying in vitro IVOC/tissue culture) will quantify these interactions and the host response using reagents and techniques establised at Edinburgh University and VLA.
Time-Scale and Cost
From: 1999

To: 2007

Cost: £603,124
Contractor / Funded Organisations
Institute for Animal Health (BBSRC)
Keywords
Animal Health              
Biotechnology              
E.coli O157              
Epidemiology              
GM Non-Food              
Plants and Animals              
Zoonoses              
Fields of Study
Animal Health