Derivation of a scrapie-free sheep flock from the progeny of a flock affected by scrapie.
The Cheviot flock at the Institute for Animal Health's Neuropathogenesis Unit (npu) has endemic scrapie, which affects primarily vrq/vrq sheep and at high frequency. A new flock with a full range of PrP genotypes, including the highly susceptible vrq/vrq, has been produced on a separate site, from animals in the npu breeding flock, and it remains scrapie-free after eight years. In contrast, in a parallel flock at the npu farm, scrapie has reappeared after five years, although the animals were kept in separate accommodation from the scrapie-affected sheep. During this time the npu breeding flock continued to have scrapie cases. Although it is known that highly susceptible sheep can remain free of infection in a clean environment, this is the first report of the infection being removed successfully from the bloodlines of scrapie-affected sheep. The results confirm that scrapie is not a genetic disease dependent only on the PrP gene sequence, but requires both genetic susceptibility and an infectious agent.
Foster
J
J
Institute for Animal Health, Neuropathogenesis Unit, West Mains Road, Edinburgh.
McKenzie
C
C
Parnham
D
D
Drummond
D
D
Goldmann
W
W
Stevenson
E
E
Hunter
N
N
D000822:Animal Husbandry; D000818:Animals; D001947:Breeding; D005260:Female; D020022:Genetic Predisposition to Disease; D008297:Male; D018620:PrPSc Proteins / Q000235:genetics* / Q000472:pathogenicity*; D012608:Scrapie / Q000235:genetics*; D012756:Sheep
D018620:PrPSc Proteins