Submitted to: Journal of General Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/1996
Publication Date: N/A
Interpretive Summary: Scrapie is a fatal disease of sheep. The causative organism and route of infection remain topics of intensive scientific scrutiny. Genetic susceptibility to clinical disease has been linked to the gene for the prion protein, a normal cellular glycoprotein which accumulated in insoluble form in diseased animals. Earlier reports suggested that oral exposure to the agent is a probable route of natural infection. In this retrospective study, 103 DNA samples from orally inoculated sheep were examined for prion gene polymorphisms. All 63 sheep that developed scrapie carried the glutamine-171 (171-Q) form of the prion gene on both chromosomes. Sheep that carried 171-Q on only one or neither chromosome did not develop clinical disease during the observation time in this study. This finding supports our earlier observation that most naturally infected sheep in the U.S. carry 171-Q on both chromosomes. Selection of breeding stock of lower susceptibility is expected to reduce the incidence of clinical scrapie.
Technical Abstract: One hundred three U.S. suffolk sheep were inoculated orally with a scrapie agent preparation and monitored for clinical disease and histopathologic lesions characteristic of scrapie. A retrospective study of the polymorphisms at codon 171 of the prion protein (PrP) gene was performed on these sheep. All 63 sheep that developed scrapie during the observation period were homozygous for the glutamine 171 (171-QQ) PrP allele. Twelve 171-QQ sheep failed to develop disease. All 5 sheep homozygous for arginine (171-RR) and all 23 heterozygous (171-QR) sheep remained free of scrapie.