NR ATMP
AU Warner,R.G.; Morris,D.; Dawson,M.
TI PrP genotype progression in flocks participating in the National Scrapie Plan for Great Britain
QU International Conference - Prion 2005: Between fundamentals and society's needs - 19.10.-21.10.2005, Congress Center Düsseldorf - Poster Session: Genetics, strains and emerging problems GEN-15
PT Konferenz-Poster
AB The National Scrapie Plan (NSP) for Great Britain (GB) is a voluntary scheme which through PrP genotype testing and restricted breeding aims to reduce the risk of scrapie in the GB sheep flock. Within its core Ram Genotyping Scheme restrictions have been placed on the use of rams with genotypes associated with reduced resistance (any bearing the VRQ allele of the ovine PrP gene and any lacking ARR). To gauge progress in member flocks and within breeds we have monitored the genotype profile of successive crops of ram lambs. We can report that between 2002 and 2004 the proportion of ram lambs testing in the most resistant genotype category (NSP Type 1: ARR/ARR) has risen in each of the 11 most frequently-sampled breeds. Crucially, in the same period each of these breeds has also seen a decline in the proportion of genotypes associated with highest disease-risk (i.e. X/VRQ, where X is an allele other than ARR). Interestingly, change in the proportion of ram lambs testing for ARR - heterozygous genotypes (NSP Type 2: ARR/X, where X is not VRQ) appears to be influenced by sector type. Whereas these genotypes have expanded, in relative terms, in each of six frequently-sampled hill breeds, this category has declined year-on-year in ram lambs of 4 of 5 prominent lowland/ crossing breeds. The proportion of ram lambs which carry neither ARR nor VRQ (NSP Type 3) has declined consistently in the top-11 breeds. Interestingly the ARR/VRQ genotype (NSP Type 4) has proved largely refractory to change over the course of the scheme. As well as considering the sum total of results in these breeds we have also monitored the progress made by individual NSP flocks. Encouragingly, of those flocks that presented ram lambs for NSP testing in all three years 2002-2004, the majority have experienced an increase in the proportion testing ARR/ARR and of those presenting VRQ ram lambs in 2002, most have seen a fall in their frequency by 2004.
AD R.G.Warner, D.Morris, M.Dawson, National Scrapie Plan Administration Centre, State Veterinary Service, Defra, Worcester, UK
SP englisch
PO Deutschland