scrapie

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scrapie:

see prionprion
, abnormal form of a protein found in mammals, believed to cause a group of diseases known as prion diseases or transmissible spongiform encephalopathies. Well-known prion diseases are Creutzfeldt-Jakob disease (CJD) and kuru in humans, scrapie in sheep, bovine
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Scrapie

 

a slowly developing infectious disease of sheep that is associated with degenerative changes in the central nervous system and characterized by excitability, severe itching, paralysis, and emaciation. First reported in Great Britain in 1732, scrapie is recorded today in Europe, southern Africa, India, Australia, Canada, the USA, and many other areas.

The nature of the causative agent of scrapie has not been determined. A viral hypothesis has been formulated but not substantiated. Some believe the causative agent to be a protein, whereas others believe it to be a special type of polysaccharide. There also is a membrane hypothesis, which states that the biological activity of the causative agent of scrapie is the function of a modified cell membrane.

The causative agent of scrapie is extraordinarily resistant; it can withstand boiling for three hours, is resistant to chemical agents, and preserves well in desiccated pathological material and at low temperatures. Sheep 18 months of age and older are affected. The causative agent is transmitted when sick and healthy animals are housed together and when animals graze on infected pastures. Sheep of various breeds have different susceptibilities to scrapie. Although the disease has been recorded year-round, it occurs more frequently in winter and spring. Scrapie might be related to such human diseases as multiple sclerosis and parkinsonism. The incubation period lasts one to four years. At first, infected animals are characterized by unusual behavior, increased excitability, tremors, and an abnormal gait. Itching is also a characteristic early symptom. Subsequent symptoms include emaciation, incoordination, and paralysis. The animals die several weeks after the appearance of the first symptoms.

Scrapie is diagnosed according to clinical symptoms and histological examination. A treatment has not been developed. Control and preventive measures include the refusal of entry of sheep from an infected country and the slaughter of infected flocks. Some sheep breeders discontinue hereditary lines of sheep among which scrapie has been discovered.

REFERENCES

Kukhto, A. F. “Pochesukha ovets: skreipi.” In Bolezni ovets. Moscow, 1963.
Andrewes, C. Virusy pozvonochnykh. Moscow, 1967. (Translated from English.)
Andrewes, C. Estestvennaia istoriia virusov. Moscow, 1969. (Translated from English.)

I. A. BAKULOV

scrapie

[′skrā·pē]
(veterinary medicine)
A transmissible, usually fatal, virus disease of sheep, characterized by degeneration of the central nervous system.
References in periodicals archive ?
Scrapie agent interference assay was performed to evaluate the potential for interference of the test article with the detection of Pr[P.
In the laboratory, the scrapie agent has been transmitted to hamsters, mice, rats, voles, gerbils, mink, cattle, and some species of monkeys by inoculation.
Finally, we used NIH-3T3 (ATCC-CRL1658) and L929 (ATCC-CCL1), both mouse embryo fibroblast cells, known to be infectable with the mouse-adapted 22L strain of scrapie agent as positive controls (11) (Table 1).
Molecular analysis of the abnormal prion protein during coinfection of mice by bovine spongiform encephalopathy and a scrapie agent.
This observation sustains the idea that the involved agent could belong to a particular scrapie agent group that cannot be directly identified by using the current biochemical criteria for TSE agent discrimination.
Detection of proteinase K-resistant prion protein and infectivity in mouse spleen by 2 weeks after scrapie agent inoculation.
Several characteristics of the scrapie agent suggest that the agent is not a virus but is likely composed primarily of a protein.
However, the observed persistence of the CWD agent was comparable to that of the scrapie agent, which persisted in paddocks for [approximately equal to] 1 to 3 years after removal of naturally infected sheep (7).
Our results could also suggest a common origin for sheep BSE and atypical scrapie agents, which may exhibit different phenotypes depending on the host [PrP.