scrapie(redirected from scrapie agent)
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A communicable spongiform encephalopathy of the central nervous system of sheep and goats caused by a prion and characterized by a very long incubation period followed by pruritus, abnormalities of gait, and invariably death; it resembles Creutzfeldt-Jakob disease and kuru in humans.
[from scraping by affected animals against objects to relieve itching]
scrapie/scra·pie/ (skra´pe) a prion disease occurring in sheep and goats, characterized by severe pruritus, debility, and muscular incoordination, ending in death.
A fatal neurodegenerative disease of sheep and goats caused by a prion and marked by chronic itching and loss of muscular coordination.
the first of the prion diseases to be recognized, occurring in sheep and goats and characterized by severe pruritus, muscular incoordination, and increasing debility ending in death.
A communicable spongiform encephalopathy of the central nervous system of sheep and goats caused by a prion; resembles Creutzfeldt-Jakob disease and kuru in humans.
[from scraping against objects by affected animals to relieve itching]
scrapieA fatal nervous system disease of sheep featuring a SPONGIFORM ENCEPHALOPATHY. Scrapie is caused by a PRION and has an incubation period of 2 to 7 years.
scrapiea disease of sheep, thought to be caused by PRIONS, in which the animal develops intense itching and increasing weakness, and eventually dies.
an infectious, fatal, chronic disease of sheep and goats with clinical signs of pruritus, abnormalities of gait, recumbency and a long illness of about 6 months. A transmissible spongiform encephalopathy. The incubation period is at least 2 years. Susceptibility to scrapie is genetically determined and control programs are developed to select scrapie resistant sheep.
scrapie is caused by an agent that acts like a virus but does not have the physical characteristics of one. Despite intensive study the true nature of the scrapie agent has not been defined; it is not a conventional virus or a viroid and current studies suggest that it may be a small-molecular-weight, 'self-replicating' basic protein for which the term prion has been proposed. The scrapie agent is of interest beyond its role as a rare pathogen for sheep in that it is a prototype of a new class of infectious agents responsible for a number of slow degenerative central nervous system diseases of humans and other animal species. See scrapie, prion, bovine spongiform encephalopathy, feline spongiform encephalopathy.
characteristic proteinaceous fibrils in the neurons of sheep with scrapie; the fibrils consist of membrane glycoprotein the DNA of which exists in the patient's brain cells. The glycoprotein accumulates because horizontally acquired scrapie agent induces transcription of the related host chromosomal gene and converts it to a polymerized proteinase-resistant fibrillar form.
scrapie eradication programs
most countries with scrapie have established scrapie eradication or scrapie monitoring schemes based on genotyping. According to the 2003 EU-Directive 2003/100/EC every member state has to establish a breeding program based on scrapie resistance.
scrapie eyelid test
the presence of the scrapie agent in lymphoid tissue allows its detection in the lymphoid tissue of the third eyelid in live sheep. This is in contrast to the BSE agent in cattle which does not occur in lymphoid tissue and for which there is no ante mortem test.
susceptibility to scrapie is associated with polymorphisms in the ovine prion protein (PrP) gene at codons 136, 154 and 171. Genotyping can establish resistant sheep and genotype testing for susceptibility to scrapie is a key element of the scrapie eradication program.