Author
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Miller, Janice |
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Submitted to: Journal of Dairy Science
Publication Type: Abstract Only Publication Acceptance Date: 3/18/1997 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Spongiform encephalopathy(SE) has been reported in human beings, mink, cats, and several species of ruminants. The name of these diseases is derived from the classical microscopic lesion in brain, which gives the tissue a "spongy appearance." Current evidence indicates the disease results when a protein (prion protein or PrP) becomes conformationally altered so that it cannot be destroyed by cellular enzymes. Most forms of SE can be transmitted experimentally (and sometimes inadvertently during medical procedures), indicating an infectious etiology. Because nucleic acid has not been detected in the purified transmissible material, PrP itself is believed to be the inciting agent. In human beings, some forms of SE are inherited, due to specific mutations of the prion gene, while other cases arise spontaneously as a result of genetic influences that create an unstable PrP structure. Two types of SE in animals are transmitted naturally, although the mode of transmission is not known. One of these, sheep scrapie, has been known in Europe for more than 250 years. The other condition, chronic wasting disease, affects mule deer and elk and has been recognized only in the United States. The best known animal SE, bovine spongiform encephalopathy (BSE), was first seen in England in 1986 but rapidly escalated into a large-scale epidemic. The outbreak is believed to have been caused by the feeding of protein supplements made from rendered sheep that had scrapie. In addition to cattle, several other animal species have been affected, including domestic cats and several species of zoo animals. Another example of a food-borne SE is transmissible mink encephalopathy. The mink disease also may have resulted from feeding scrapie-affected tissue but other potential sources cannot be ruled out. |