By MATTHEW L. WALD and ERIC LICHTBLAU WASHINGTON, — A sick cow slaughtered about two weeks ago near Yakima, Wash., has tested positive for mad cow disease in early laboratory results, the first such case in the United States, the secretary of agriculture said on Tuesday. Shortly after the announcement, Japan said it was banning imports of American beef. The South Korean agriculture ministry said in a statement that South Korea was also halting American beef imports and that it was pulling American beef products off supermarket shelves. [On Wednesday morning, Russia, Thailand and Hong Kong also announced that they too were banning imports of American beef products.] Copyright 2003 The New York Times Company

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Susan Milius As Canadian health officials press on in their investigation of mad cow disease within their borders and other countries bar Canadian beef, scientists are taking disparate approaches to developing defenses against such brain diseases. Researchers in the United Kingdom studying livestock that resist so-called transmissible spongiform encephalopathies report mixed results. Although earlier tests had found some sheep resistant to infection by natural routes, extreme challenges—injections of diseased material directly into the brain—brought on the disease in 3 out of 19 animals, says Fiona Houston of the Institute for Animal Health in Newbury in the May 29 Nature. Looking at meat treatments, U.S. and Italian researchers are blasting hot dogs with pressure and heat to inactivate agents for a spongiform encephalopathy. The researchers report in the May 13 Proceedings of the National Academy of Sciences that they have quashed risk of infection from the food. Copyright ©2003 Science Service.

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By MATT RIDLEY VANCOUVER, British Columbia — Alarming as it was to learn last week that mad cow disease had appeared in North America, the news could have been far worse. Thanks to advances in bioscience and technology, we can now stop an epidemic like mad cow disease, and its human offshoot, Creutzfeldt-Jakob disease, in its tracks. Little is known so far about the particular case discovered last week in western Canada. The black Angus cow was 6 to 8 years old, officials said, and had lived on six ranches and had had five or more calves. Nine herds have been quarantined so far. In Britain, the mad cow epidemic that began in the late 1980's infected nearly 200,000 cattle before it was halted, and more than 120 people died through infected meat. The episode shattered the British public's confidence in government reassurances about food safety, and contributed heavily to British and European refusal to accept official assurances about the safety of genetically modified crops. The environmental movement managed to make much of this distrust, using it to promote fears of interfering with nature, whether through technology or industrial agriculture. Copyright 2003 The New York Times Company

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By CLIFFORD KRAUSS with SANDRA BLAKESLEE VANCOUVER, British Columbia, — Mad cow disease was diagnosed in a cow in Canada today, and United States health authorities immediately placed a ban on imports of beef, cattle and animal feed from Canada. The report shocked ranchers through much of western Canada, where trading in livestock was immediately halted because of plummeting cattle prices. The shock waves spread through the financial markets, where prices in many Canadian and American meat and restaurant companies fell sharply. Canadian authorities stressed that only one cow out of Canada's total cattle population of 3.6 million was found to be sick and there was no immediate evidence that the disease had spread among livestock or humans. Copyright 2003 The New York Times Company

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By NICHOLAS WADE Deep in the recesses of the human heart, lurking guiltily beneath the threshold of consciousness, there may lie a depraved craving — for the forbidden taste of human flesh. The basis for this morbid accusation, made by a team of researchers in London, is a genetic signature, found almost worldwide, that points to a long history of cannibalism. The signature is one that protects the bearer from infection by prions, proteins that can be transmitted in infected meat and attack the nerve cells of the brain. Prions can be acquired from eating infected animals, as in the case of the mad cow disease that in 1996 spread to people in England, but they spread even more easily through eating infected humans. This fact is known from study of the Fore, a tribe in the eastern highlands of Papua New Guinea that started to practice ritual cannibalism at the end of the 19th century. Dr. D. Carleton Gajdusek, who later received a Nobel Prize for his work, noticed that the Fore were being devastated by a neurodegenerative disease known as kuru. He linked it with their practice of eating the brains of their dead in mortuary feasts. When the feasts were banned by Australian authorities in the mid-1950's, the incidence of kuru declined, and no cases have appeared in anyone born after that time. Copyright 2003 The New York Times Company

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— Howard Hughes Medical Institute researchers have found that a gene mutation that produces a black coat color in mice also causes degeneration of neurons similar to that observed in prion-caused diseases, such as Creutzfeldt-Jakob disease and “mad cow disease.” The scientists say that their findings could improve understanding of how the renegade proteins, called prions, destroy the brains of infected humans, cattle and sheep. In an article published in the January 31, 2003, issue of the journal Science, researchers led by Howard Hughes Medical Institute investigator Gregory Barsh reported that a gene mutation in mahoganoid mice causes neural damage that closely resembles that observed in spongiform encephalopathies. The work was carried out by Lin He and Teresa Gunn, graduate student and former postdoctoral fellow with Barsh, respectively, and also involved collaboration with the University of Michigan School of Medicine. Gunn, He, and Barsh began looking at the effects of mahoganoid mutation on neural development after their studies of another mutation in a similar coat-color gene, called Attractin, turned up some intriguing results. ©2003 Howard Hughes Medical Institute

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Researchers puzzle over brain illness in North American wildlife Susan Milius This autumn, the nation's big-game hunters are lifting their guns and bows in the service of science. They're collecting the biggest sample ever of deer and elk brains—predicted to total 200,000—to test for a once-obscure wildlife disease that's become the stuff of headlines and headaches coast-to-coast. So-called chronic wasting disease strikes mule deer, white-tailed deer, and elk. It riddles the brain with tiny holes as the victim slowly withers and dies. Once found in the wild only in an area intersecting Colorado, Wyoming, and Nebraska, the disease appears to be spreading. This year, it turned up in wild herds in South Dakota, New Mexico, and Canada and jumped all the way to Wisconsin and Illinois. This disease belongs to the same class of maladies as mad cow disease, which appeared in Britain in 1986 and about a decade later, showed up in people who had eaten tainted meat. Last year, some 11 million people hunted deer and elk in the United States, and many more helped them eat their prizes. So far, the news for hunters looks reassuring. Several weighty groups, including a panel from the World Health Organization, have concluded that there's no evidence so far that people can catch chronic wasting disease. From Science News, Vol. 162, No. 22, Nov. 30, 2002, p. 346. Copyright ©2002 Science Service. All rights reserved.

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By SANDRA BLAKESLEE DENVER, — Wildlife experts from the United States and Canada are meeting here to discuss strategies for containing the spread of chronic wasting disease, the variant of mad cow disease that kills deer and elk. The malady, once found only in the brushy foothills near Fort Collins, Colo., has now been identified in both captive and wild herds of deer and elk in Kansas, Montana, Nebraska, New Mexico, Oklahoma, South Dakota, Wisconsin and Wyoming and the Canadian provinces of Saskatchewan and Alberta. Some states, like New Mexico, have found only one infected animal in the wild. But Saskatchewan, for example, has diagnosed the disease in more than 100 captive animals bred for their meat and antlers. Copyright 2002 The New York Times Company

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Experts offer some advice on deer illness By BRIAN TUMULTY Press-Gazette Washington bureau WASHINGTON — Scientists and wildlife experts testifying at a congressional hearing Thursday acknowledged there are many unanswered questions about the always fatal chronic wasting disease that has infected deer and elk in eight states ranging from Colorado to Wisconsin. But they did offer some basic advice for the public: Q. How likely is it that people may become infected? A. It’s highly unlikely. “There’s no evidence that chronic wasting disease poses a threat to humans,” said Russell George, director of the division of wildlife at the Colorado Department of Natural Resources. Q. What does the disease do? A. Animals become emaciated or “wasted” by chronic weight loss. Chronic wasting disease, or CWD as it is often called, is always fatal. But it usually takes 16 to 32 months to incubate. Animals often become listless, lower their heads and walk in repetitive patterns. Some infected elk become highly excited and nervous. Q. Is the disease a virus or bacteria? A. Neither. CWD is a form of protein, according to wildlife veterinarian Michael Miller of the Colorado Department of Natural Resources. It is scientifically described as a transmissible spongiform encephalopathy or TSE. Once an animal is infected, the toxicity builds until the animal dies. Copyright © 2002

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National Institutes of Health (NIH) scientists investigating how prion diseases destroy the brain have observed a new form of the disease in mice that does not cause the sponge-like brain deterioration typically seen in prion diseases. Instead, it resembles a form of human Alzheimer's disease, cerebral amyloid angiopathy, that damages brain arteries. The study results, reported by NIH scientists at the National Institute of Allergy and Infectious Diseases (NIAID), are similar to findings from two newly reported human cases of the prion disease Gerstmann-Straussler-Scheinker syndrome (GSS). This finding represents a new mechanism of prion disease brain damage, according to study author Bruce Chesebro, M.D., chief of the Laboratory of Persistent Viral Diseases at NIAID’s Rocky Mountain Laboratories. Prion diseases, also known as transmissible spongiform encephalopathies, primarily damage the brain. Prion diseases include mad cow disease or bovine spongiform encephalopathy in cattle; scrapie in sheep; sporadic Creutzfeldt-Jakob disease (CJD), variant CJD and GSS in humans; and chronic wasting disease in deer, elk and moose. The role of a specific cell anchor for prion protein is at the crux of the NIAID study. Normal prion protein uses a specific molecule, glycophosphoinositol (GPI), to fasten to host cells in the brain and other organs. In their study, the NIAID scientists genetically removed the GPI anchor from study mice, preventing the prion protein from fastening to cells and thereby enabling it to diffuse freely in the fluid outside the cells.

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By SANDRA BLAKESLEE Researchers are reporting that they have solved a longstanding mystery about the rapid spread of a fatal brain infection in deer, elk and moose in the Midwest and West. The infectious agent, which leads to chronic wasting disease, is spread in the feces of infected animals long before they become ill, according to a study published online Wednesday by the journal Nature. The agent is retained in the soil, where it, along with plants, is eaten by other animals, which then become infected. The finding explains the extremely high rates of transmission among deer, said the study’s lead author, Dr. Stanley B. Prusiner, director of the Institute for Neurodegenerative Diseases at the University of California, San Francisco. First identified in deer in Colorado in 1967, the disease is now found throughout 14 states and 2 Canadian provinces. It leads to emaciation, staggering and death. Unlike other animals, Dr. Prusiner said, deer give off the infectious agent, a form of protein called a prion, from lymph tissue in their intestinal linings up to a year before they develop the disease. By contrast, cattle that develop a related disease, mad cow, do not easily shed prions into the environment but accumulate them in their brains and spinal tissues. There is no evidence to date that humans who hunt, kill and eat deer have developed chronic wasting disease. Nor does the prion that causes it pass naturally to other animal species in the wild. Copyright 2009 The New York Times Company

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By Rachel Ehrenberg Researchers look to the good version of the protein implicated in mad cow disease for insight into the protein’s bad side. When the nefarious Mr. Hyde takes his own life, the good Dr. Jekyll is also killed. Scientists are adopting the reverse approach for halting the protein behind prion diseases such as Creutzfeldt-Jakob and mad cow. By targeting the harmless version of the brain protein whose evil alter ego brings on disease, researchers have prevented the bad version of the protein from continuing its rampage in the brains of infected mice. The results are reported online July 14 in Proceedings of the National Academy of Sciences. The approach of killing Jekyll to get Hyde is very promising, comments biochemist Sina Ghaemmaghami of the Institute for Neurodegenerative Diseases at the University of California, San Francisco. The sinister version of the protein comes in several slightly different forms, making it hard to develop a single attack strategy, Ghaemmaghami says. Led by neuroscientist Giovanna Mallucci of University College London, researchers delivered bits of attack RNA to interfere with production of the normal version of the prion protein. In animals who have prion disease, this protein somehow gets converted into a dangerous form, which then travels through the brain, coaxing other good versions of the protein to go bad. © Society for Science & the Public 2000 - 2008

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Roxanne Khamsi Silencing the genes that produce prion proteins can dramatically slow the progression of mad cow disease, suggests a new study in mice. Researchers say that the approach might one day work to treat human prion illnesses, such as variant Creutzfeldt Jakob Disease (vCJD). People can contract vCJD after eating meat contaminated with mad cow disease. Though the illness is extremely rare, it can lead to schizophrenia-like psychosis and typically causes death within a year of diagnosis. While doctors can prescribe drugs to temporarily treat some of the symptoms of prion disease, which include seizures, they still have no way to stop the progression of the illness. Alexander Pfeifer at the University of Bonn in Germany, and colleagues, explored the possibility of fighting prion disease in mice using a method of gene silencing known as RNA interference (RNAi). This method exploits messenger RNA (mRNA) sequences in the cell, which are responsible producing proteins by using the animal’s genetic code as an instruction list. RNAi relies on molecules that bind to mRNA sequences in the cell, thereby preventing the production of specific proteins. © Copyright Reed Business Information Ltd

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Scientists for the first time have watched agents of brain-wasting diseases, called transmissible spongiform encephalopathies (TSE), as they invade a nerve cell and then travel along wire-like circuits to points of contact with other cells. These findings will help scientists better understand TSE diseases and may lead to ways to prevent or minimize their effects. TSE, or prion, diseases include scrapie in sheep and goats; chronic wasting disease in deer and elk; mad cow disease in cattle; and Creutzfeldt-Jacob disease in humans. Under the direction of Byron Caughey, Ph.D., at the Rocky Mountain Laboratories (RML) and Marco Prado, Ph.D. at the University of Minas Gerais in Belo Horizonte, Brazil, the team performed the research in laboratory cultures using a rodent-adapted form of scrapie protein and cells taken from the central nervous system of mouse and hamster brains. The proteins were first “branded” with fluorescent dyes so they could be easily tracked. The work also revealed that a similar trafficking process might occur with the key plaque-forming protein in Alzheimer’s disease, which is not a TSE but a different type of degenerative brain disease, according to Gerald Baron, Ph.D., one of the lead RML researchers. RML, located in Hamilton, MT, is part of the National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health. The new report appears in the May 25 issue of The Journal of Neuroscience. “These findings offer intriguing leads toward developing therapies to stop the spread of TSE and possibly other degenerative brain diseases,” says NIAID Director Dr. Anthony Fauci.

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The discovery of a cow suffering from bovine spongiform encephalopathy (BSE) in Washington State at the end of last year brought fears of mad cow disease to the U.S. New findings provide further insight into how prions, the misshapen proteins behind the transmissible spongiform encephalophathy (TSE) diseases, behave. Prions are most often associated with organ tissue but recent findings have indicated that they can accumulate in the muscles of rodents and humans who have succumbed to TSEs. According to a report published online today by the journal Nature Biotechnology, prions can be detected in the muscles of sheep infected with the TSE known as scrapie several months before the disease can be clinically diagnosed. Olivier Andreoletti of National Veterinary School in Toulouse, France and his colleagues infected six sheep with scrapie. After the animals died, the researchers analyzed their muscle tissue and found "small but consistent amounts" of the infectious prion in the creatures’ fore and hindlimbs. The scientists also examined a flock of sheep that had naturally succumbed to scrapie and detected prions in the muscles of two animals out of a dozen that were tested. One of these, which was 13.5 months old when it died, tested positive even though animals typically display clinical signs of scrapie only after 22 months of age. Fewer of the naturally-infected animals tested positive for prions in their muscles, suggesting that the infectious proteins spreads to muscles less efficiently in the wild than in the laboratory. In addition, the prions in the muscle tissues were 5,000 times less infective than were those recovered from brain tissue. Although this is the first observation of prions accumulating in the muscles of animals that enter the human food chain, the authors caution that the results cannot be extrapolated to BSE in cattle. In addition they note that "dietary exposure to scrapie is currently considered nonhazardous to humans." --Sarah Graham © 1996-2004 Scientific American, Inc

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Detailed structural studies have revealed new insights into why the same prion protein can have different properties and be either weakly or strongly infectious. The researchers said their observations in prions that infect yeast are likely to hold true for the sorts of prions that infect humans and animals. A research team led by Howard Hughes Medical Institute investigator Jonathan S. Weissman analyzed the structures of two unmodified yeast Sup35 prion proteins in two infectious conformations. They identified key structural differences that explain the different behaviors of these prions. The researchers published their findings online September 2, 2007, in the journal Nature. Weissman and his colleagues are at the University of California, San Francisco. The scientists studied yeast prions, which are similar to mammalian prions in that they act as infectious proteins. In recent years, mammalian prions have gained increasing notoriety for their roles in such fatal brain-destroying human diseases as Creutzfeldt-Jakob disease and kuru, and in the animal diseases, bovine spongiform encephalopathy (“mad cow” disease) and scrapie. Yeast and mammalian prions are proteins that transmit their unique characteristics via interactions in which an abnormally shaped prion protein influences a normal protein to assume an abnormal shape. In mammalian prion infections, these abnormal shapes trigger protein clumping that can kill brain cells. In yeast cells, the insoluble prion protein is not deadly; it merely alters a cell's metabolism. Prions propagate themselves by division of the insoluble clumps to create “seeds” that can continue to grow by causing aggregation of more proteins. © 2007 Howard Hughes Medical Institute.

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Howard Hughes Medical Institute researchers have identified small regions within a yeast protein that control the protein's conversion to an infectious agent known as a prion. Yeast prions are proteins that are conceptually similar to the mammalian prions that have gained notoriety for their roles in such fatal brain-destroying human diseases as Creutzfeldt-Jakob disease and kuru, and in the animal diseases, scrapie and bovine spongiform encephalopathy, or “mad cow disease.” “No one knew that prion conversion was controlled by such a small region, and in such a specific way,” said HHMI investigator Susan Lindquist at the Whitehead Institute for Biomedical Research. Lindquist and postdoctoral fellow Peter Tessier published a research article describing their findings on May 10, 2007, in the journal Nature. The precision of this process offers key insights into the mysterious behavior of prions, Lindquist observed. Different configurations of the recognition region cause the prion to assume different shapes, or variants. “We've been able to understand some fundamental questions about how prions form different strains and how they establish and overcome species barriers,” said Tessier. First isolated and purified in the early 1980s, prions are proteins that can fold into self-templating configurations, so that proteins of the same type adopt the same configuration. © 2007 Howard Hughes Medical Institute.

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Debora MacKenzie A third person in the UK has caught variant CJD from another human, in a blood transfusion. Many more people may be at risk of this human form of BSE, experts warn. Three of eight people tested so far in the UK are now confirmed to have been infected with vCJD through blood transfusions, autopsies have revealed. A total of 66 people in UK are known to have received transfusions from blood donors who later went on to develop vCJD. Of those, 34 later died from other causes. The remaining 24 people have been informed that they may be at high risk of developing vCJD, but are not reported to have been tested. In each of the three cases, the victims received blood from someone who went on to develop vCJD between 18 and 40 months after donating blood, which shows that apparently healthy blood donors can pose a threat of infection, at least in the late stages of incubation. Many carriers, unaware of their infection, may have transmitted the mutant prion in donated blood, experts say. For that reason, it was “prudent” in 2004, once the first transfusion-related case was discovered, for the UK to ban transfusion recipients from later donating blood, say Kumanan Wilson and Maura Ricketts of Toronto General Hospital and the Public Health Agency of Canada. They penned a commentary on the case in the medical journal The Lancet, which reported the third case this week (see vCJD death linked to blood transfusion. © Copyright Reed Business Information Ltd.

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Two independent research groups have established conclusively that prions are proteins, and that they do not depend on genes or other factors for transmission of their traits. According to the scientists, the studies answer a nagging question that had raised doubts among some researchers about the validity of the so-called “protein-only” hypothesis of prion infectivity. Scientists have grappled for years with one of the central tenets of the protein-only hypothesis, namely, that a single prion protein, when unaltered by genetic mutation, can give rise to different strains of prions with varying infectivity and other properties. The two research groups established that the strains could be accounted for by different misfolded conformations of the same protein. The researchers say this finding could contribute to better understanding of the functioning of disease-causing prions in animals and humans. Both groups published their findings in the March 18, 2004, issue of the journal Nature. Howard Hughes Medical Institute investigator Jonathan S. Weissman at the University of California at San Francisco led one group. The other effort was led by Chi-Yen King at Florida State University. ©2004 Howard Hughes Medical Institute

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Genetic technique may yield BSE-proof calves. MICHAEL HOPKIN Researchers in the United States and Japan claim to have created cow embryos that cannot produce the protein responsible for bovine spongiform encephalopathy (BSE). Without it, the animals should be immune to mad cow disease. A “handful" of the BSE-free cows will be born early next year, the researchers say. The calves will be tested with a small dose of mad cow protein to see whether they are truly resistant to the disease. The BSE-causing protein, called a prion, is present in both healthy and diseased cattle; it is only when it twists out of shape that it causes problems. When normal prion protein comes into contact with the disease-causing version it can flip into the malignant form, causing rogue prions to spread through the brain. This leads to coordination problems, behavioural changes and death. The US and Japanese researchers aimed to bypass this problem by creating genetically engineered cows that do not produce prions at all. This means that they should be safe from small doses of diseased prions, explains James Robl, president of biotechnology firm Hematech in Sioux Falls, South Dakota, and one of the leaders of the team. © Nature News Service / Macmillan Magazines Ltd 2003

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