Defra - Department for Environment, Food and Rural Affairs.

Science Search

Science and Research Projects

Return to Science Search homepage   Return to Project List

PrPSc and associated infectivity in ARR/ARR sheep by biochemical and transgenic techniques - SE1854

The Government’s scrapie control policy and the National Scrapie Plan (NSP) aim to replace the scrapie susceptible genotypes in the UK flock with scrapie resistant genotypes such as ARR/ARR. However, following reports of experimental infection in ARR/ARR sheep after intra-cerebral challenge with TSE, the identification of apparent sub-clinical infection in such genotypes through serial mouse passage, and the recognition of atypical scrapie forms, there are fears that the resistant genotypes themselves could act as occult carriers and as such pose a potential risk to human health.This study will make extensive use of archived tissues from the VLA ovine TSE research programme and will use a range of validated but novel and highly sensitive biochemical and immunological tests and transgenic mouse bioassay to search for very low levels of infectivity in selected tissues. An additional short term challenge study will also be carried out to follow the response of the ARR/ARR lamb to a high dose of a known strain of scrapie and to attempt to identify whether the infection does penetrate beyond the gut and/or to investigate whether there is some “barrier” that contributes to the “resistance”. The results will be of immediate relevance to the scrapie control policy and will enable the potential risk of scrapie infection in the ARR/ARR to be properly quantified and for appropriate health safeguards, such as exclusion of certain tissues from the food-chain, to be introduced. They will also guide animal health policies including issues such as restocking after depopulation of a scrapie infected farm. It is anticipated that initial results will be available in the first year.
Project Documents
• Executive Summary : Test the potential presence of scrapie PrPSc and any associated infectivity in naturally exposed and/or experimentally challenged ARR/ARR sheep using transgenic techniques and prescreening assay   (32k)
Time-Scale and Cost
From: 2005

To: 2008

Cost: £779,835
Contractor / Funded Organisations
Federal Research Centre for Virus Diseases of Animals, Veterinary Laboratories Agency
Animal Health              
Plants and Animals              
Fields of Study
Animal Health