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Variations in the virulence of Campylobacter jejuni strains associated with poultry and poultry meat
Project Code: B01005
Veterinary Laboratories Agency, Department of Bacterial Diseases, Veterinary Laboratories Agency
In this project we have investigated the ability of campylobacters, isolated from poultry, to invade human intestinal cells. Firstly we developed a tissue culture model of invasion, using a human intestinal cell line, suitable for screening many isolates. Over 100 poultry isolates were screened. The results showed that only about 2% of poultry strains were highly invasive while most strains are low invaders. Interestingly the proportion of highly invasive strains is higher (up to 20%) in isolates from human disease. These results suggest that invasion has a role in the disease symptoms seen in humans but that not all the campylobacters present in poultry are able to cause disease in this way.
Although campylobacters cannot grow in food they must survive food processing before infecting a human being. Most processing and kitchen conditions are very hostile to this bacterium but it very adaptable and have developed many ways to overcome such conditions. We next asked whether such adaptations to the hostile conditions of food processing can affect the campylobacters’ ability to cause disease. Using strains isolated from a poultry abattoir, as well as strains exposed to conditions like heat, cold and water washes in a model system, we have shown that the invasiveness of campylobacters may be increased by processing, but this is rare.
Finally we have attempted to define the mechanisms involved in campylobacter invasion using recently developed methods to genetically manipulate the organism. Our preliminary results have identified at least one of the campylobacter genes associated with invasion. The identification of such genes would allow the development of rapid tests, which could then be used to screen material in the foodchain for disease-causing camp
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