Mapping resistance to Campylobacter in the chicken

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Food security is an increasing priority for the UK Government and food safety is a key component of this. Campylobacter is the most common cause of food poisoning in the UK and is responsible for an estimated 321,000 estimated cases in England and Wales in 2008, with over 15,000 hospitalisations and 76 deaths. Campylobacter accounts for a third of the cost of food-borne illness in England and Wales, estimated at £583 million in 2008. It is found mainly in poultry and control of the organism in this reservoir is expected to lower the inclidence of human infection."Campylobacter is a highly complex organism and we will only be able to understand it more fully and to overcome the threat it poses by deploying world-class research across microbiology, immunology and molecular biology... Addressing the Campylobacter challenge involves two of the three BBSRC strategic priorities of food security and basic bioscience underpinning health, in addition to exploiting systems approaches and new research tools." Professor Douglas Kell, BBSRC CEO.The UK Research and Innovation Strategy for Campylobacter, 2010-2015, is joint funded by the FSA, BBSRC, DEFRA, DARDNI and the Scottish Government. The overarching aim for the funders is to reduce the incidence of Campylobacter infections in humans, through reduction of the level of the bacterium in its farm animal hosts and the potential for cross-contamination in the food chain. Two of the main research priorities are understanding colonisation in the chicken and the chicken's immune response, and development of greater resistance to Campylobacter colonisation in the chicken. However, research in either of these areas was not included in a recent joint call for research into control of Campylobacter.The availability of chickens with significant innate resistance to Campylobacter colonisation would represent a safe, cost-effective solution. We have shown that genetic variation influences resistance to Campylobacter colonisation in chickens, with one line able to reduce levels of the bacterium in the gut by up 10,000-fold relative to another line. Complex genetic analysis in these inbred chicken lines has indicated that some of the regions, or loci, associated with resistance overlie known bacterial resistance genes. In this proposal we will investigate these loci further to locate the beneficial genes or mutations.We will carry out further work to map resistance genes, coupled with using the latest methods that allow selection of genes throughout the whole genome. Using tools such as new generations of high density panels to detect single nucleotide polymorphisms (changes in a single base of DNA between two different individuals at the same site) (~750k can be analysed at once), we can identify animals with candidate resistance genes that can be used to select future generations of chickens with robust resistance and greatly reduced levels of Campylobacter colonisation. As recommended by the Strategy, we will carry out this genetic research in collaboration with industry (Aviagen, a UK-based company that produces the pedigree chickens from which are generated over 50% of the world's 50 billion chickens every year), since gene association studies must be implemented in poultry breeding programmes. It is likely that resistance to Campylobacter depends on multiple genes and the selection of resistant lines will depend on the identification of specific traits and candidate animals. Though potential also exists to control Campylobacter on farm via improvements to hygiene and biosecurity, dietary modification, novel antimicrobial agents and vaccination, we believe that the proposed project would allow a targeted and rapid approach to breeding lines of poultry more resistant to Campylobacter colonisation.