NR ABCJ
AU Baylis,M.; Goldmann,W.; Houston,E.F.; Cairns,D.; Chong,A.; Ross,A.; Smith,A.; Hunter,N.; McLean,A.R.
TI Scrapie epidemic in a fully PrP-genotyped sheep flock
QU Journal of General Virology 2002 Nov; 83(11): 2907-14
IA http://vir.sgmjournals.org/cgi/content/full/83/11/2907
PT journal article
AB In scrapie-affected sheep flocks, host PrP genotype plays a vital role in determining which sheep will succumb to scrapie and the incubation period. Consequently, within-flock scrapie dynamics is best understood within the context of the genotype profile of the flock. Here we describe a 17 month epidemic of scrapie in a commercially farmed flock of 230 genotyped Texel sheep. At the start of the study, 70% of the sheep were of three genotypes only: ARR/ARQ, ARH/ARQ and ARQ/ARQ. Only 15% of sheep encoded the disease-associated VRQ allele and only a single sheep (0.4%) was of the most susceptible VRQ/VRQ genotype. For susceptible genotypes there was a marked deficit (P<0.025) of older animals (> or =3 years), implying that some cases of scrapie had occurred previously. In the ensuing 17 months, 18 sheep of known genotype were confirmed positive for the disease: seven VRQ/ARQ, six VRQ/ARH, two VRQ/ARR, three ARQ/ARQ. Median ages at death were 2.7, 2.8, 4.2 and 3.8 years respectively. Mortality rates were 55, 86, 13 and 3% respectively. Survival analysis revealed a highly significant effect of genotype on survivorship, but no difference between VRQ/ARQ and VRQ/ARH, or between VRQ/ARR and ARQ/ARQ. There was no difference in the survivorship of middle- and older-age cohorts of susceptible sheep. Scrapie risk group (as defined by PrP genotype) was not associated with submission as a scrapie suspect but later found to be negative, or with dying of unknown causes on the farm.
MH Age Factors; Animals; *Disease Outbreaks; Female; Genotype; Male; Prions/*genetics; Research Support, Non-U.S. Gov't; Scrapie/*epidemiology/etiology/mortality; Sheep; Survival Rate
AD Matthew Baylis (matthew.baylis@bbsrc.ac.uk), E. Fiona Houston (fiona.houston@bbsrc.ac.uk), Institute for Animal Health, Compton Laboratory, Compton, Newbury, Berkshire RG20 7NN, UK; Rowland R. Kao, Angela R. McLean, Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK; Wilfred Goldmann (wilfred.goldmann@bbsrc.ac.uk), Dorothy Cairns, Angela Chong, Arlene Ross, Allister Smith, Nora Hunter (nora.hunter@bbsrc.ac.uk), Institute for Animal Health, BBSRC and MRC, Neuropathogenesis Unit, Ogston Building, West Mains Road, Edinburgh EH9 3JF, Scotland, UK
SP englisch
PO England