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A preliminary analysis of existing data to provide evidence of a genetic basis for resistance of cattle to infection with M. bovis and for reactivity to currently used immunological diagnostic tests. - SE3040

There is both anecdotal evidence pointing to genetic variation for resistance of cattle to infection of M. bovis, and published experimental evidence in deer for significant genetic variation in resistance and reactivity to diagnostic tests. However this has not been properly quantified in the cattle population and it remains a possibility that such genetic variation exists and is a factor influencing the outbreak currently observed in the UK. The genetic variation may be expressed in resistance to infection, in the response to the diagnostic tests, or both. The opportunity exists to test these hypotheses using the data collected during the curent outbreak on animals that react to the disgnostic test and/or exhibit disease and combining this data with industry databases, particularly dairy databases, that contain additional information on herd mates and pedigree.

The outcome of this analysis will firstly resolve the debate on the potential extent of genetic variation in the UK herd in resistance and reactivity to diagnostic tests and will inform subsequent epidemiological analysis. Secondly, given the presence of genetic variation, the results will: (i) provide a preliminary quantification of the impact that current testing policies may have on the degree of resistance to infection present in the cattle population, and would provide recommendations on if and how the tests may be adapted to avoid such negative consequences; (ii) provide breeding companies with information that will allow them to target the marketing of bulls identified as genetically more resistant to areas in which M. bovis is more prevalent; (iii) provide a firm foundation for the identification of genes with large effect on resistance, which in turn will lead to more effective breeding programmes.
To achieve the aims of examining the extent of genetic variation, breed and pedigree information will be obtained from industry databases on animals present in the Vetnet TB database, and similarly on contemporaneous herdmates, and this collected information will be subject to a quantitative genetic analysis using models that are appropriate to the epidemiological context.
Specific objectives are:

1. Identify herds and cattle present in the Defra VETnet TB database in CTS and dairy industry databases. (3 months)
2. Using the linkage established between VETnet, CTS and industry databases, develop an integrated database identifying both animals appearing in the VETnet TB database and their contemporaries present at the time of testing with pedigree and relevant spects of performance. (1 month)
3. Define and calculate a set of epidemiological and genetic covariates to be used for modelling. (3 months).
4. Construct and refine models of TB-related data accounting for genetic, operational and environmental factors. (4 months)
5. Interpret outcomes and develop recommendations from final models (1 month).
Objective 1 will be primarily addressed by sub-contractor SAC with Roslin and VLA assistance, whilst the remaining objectives will be addressed primarily by Roslin, with VLA and SAC assistance.
Project Documents
• Final Report : A preliminary analysis of existing data to provide evidence of a genetic basis for resistance of cattle to infection with M.bovis and for reactivity to currently used immunological diagnostic tests   (350k)
Time-Scale and Cost
From: 2007

To: 2008

Cost: £147,609
Contractor / Funded Organisations
Roslin Institute, Edinburgh (BBSRC)
Animal Diseases              
Animal Health              
Bovine Immunology              
Bovine Tuberculosis              
Plants and Animals              
Fields of Study
Animal Health