By STEPHANIE STROM The Department of Agriculture announced that it had identified a case of mad cow disease, the first in six years, in a dairy cow in central California. The cow “was never presented for human consumption, so it at no time presented a risk to the food supply or human health,” John Clifford, chief veterinary officer at the department, said in a statement. Dr. Clifford noted that milk did not transmit bovine spongiform encephalopathy, the scientific name for mad cow disease. He expressed confidence in the health of the nation’s cattle and the safety of beef during a press briefing in Washington. The animal had been picked up from the farm and taken to a rendering plant, which noticed some of the signs of B.S.E., such as unsteadiness and aggression, and notified U.S.D.A. inspectors, Dr. Clifford said in a brief interview. The body will remain at the rendering facility and will be disposed of once the agency completes its investigation, probably by incineration or some other method that ensures the destruction of its tissues. It was the fourth reported case of mad cow disease, a degenerative disease that affects the brains and spinal cords of cattle, in the United States. Humans can contract the disease by eating meat from an infected cow. Only one case of mad cow disease in the United States was of the type derived from feed. That case set off a panic in 2003 when a Canadian-born cow in Washington state tested positive. © 2012 The New York Times Company

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Link ID: 16708 - Posted: 04.25.2012

Bijal P. Trivedi On a frigid winter's morning in 1992, Susan Lindquist, then a biologist at the University of Chicago in Illinois, trudged through the snow to the campus's intellectual-property office to share an unconventional idea for a cancer drug. A protein that she had been working on, Hsp90, guides misfolded proteins into their proper conformation. But it also applies its talents to misfolded mutant proteins in tumour cells, activating them and helping cancer to advance. Lindquist suspected that blocking Hsp90 would thwart the disease. The intellectual-property project manager she met with disagreed, calling Lindquist's idea “ridiculous” because it stemmed from experiments in yeast. His “sneering tone”, she says, left an indelible mark. “It was actually one of the most insulting conversations I've had in my professional life.” It led her to abandon her cancer research on Hsp90 for a decade. Today, more than a dozen drug companies are developing inhibitors of the protein as cancer treatments. Lindquist seems able to shrug off such injustices, now. Her work over the past 20 years has consistently challenged standard thinking on evolution, inheritance and the humble yeast. She has helped to show how misfolded infectious proteins called prions can override the rules of inheritance in yeast, and how this can be used to model human disease. She has also proposed a mechanism by which organisms can unleash hidden variation and evolve by leaps and bounds. She was the first female director of the prestigious Whitehead Institute for Biomedical Research in Cambridge, Massachusetts, and has received more than a dozen awards and honours in the past five years. In a paper being published this week in Nature, she and her colleagues show that in wild yeast, prions provide tangible advantages, such as survival in harsh conditions and drug resistance1. © 2012 Nature Publishing Group

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Link ID: 16388 - Posted: 02.16.2012

By Rebecca Cheung The protein-based pathogens known as prions may pass between different species more easily than has been thought, a team of French researchers reports in the Jan. 27 Science. By infecting engineered mice with prions from cows and goats, scientists also have shown that the invaders readily target tissues other than the brain. “We may underestimate the threat posed by some of these diseases by focusing only on the brain,” says Pierluigi Gambetti, a prion researcher at Case Western Reserve University in Cleveland. “It adds a new element to the equation.” The research also raises the possibility that new prion strains recently identified in cattle and small rodents might be able to jump to other species, including humans. “We should, in the future, be more exhaustive when looking at the possibility of prions being passed from one species to another,” says Hubert Laude, a professor at the French National Institute for Agricultural Research in Jouy-en-Josas and a coauthor of the study. Prions closely resemble normal proteins made by a host. When prions invade a host, they propagate by forcing these normal host proteins, actually called prion proteins, to assemble improperly. When these malformed proteins accumulate in the brain, they cause mind-wasting conditions such as Creutzfeldt-Jakob disease in people and scrapie in sheep. © Society for Science & the Public 2000 - 2012

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Link ID: 16304 - Posted: 01.28.2012

By Tina Hesman Saey Infectious proteins that cause brain-wasting conditions like mad cow disease appear to build up in the brain long before initiating the cascade of deterioration that leads to dementia and death, a new study of mice finds. The findings suggest that other factors besides the misshapen infectious proteins characteristic of prion diseases may control the lethality of the disease. If scientists can determine what those factors are, future treatments may be able to prevent the infectious protein diseases — which include mad cow disease, scrapie in sheep and Creutzfeldt-Jakob disease in people — from progressing to a fatal stage. “We don’t know what’s going on here, but we do know there’s something interesting,” says John Collinge, director of the United Kingdom Medical Research Council Prion Unit in London, who headed the new study. Findings reported by Collinge and his colleagues in the Feb. 24 Nature contradict the idea that infectious versions of a normal brain protein called PrP accumulate slowly, gradually twisting all of the healthy copies of the protein into a disease-causing form. Researchers have thought that the disease-causing prions slowly build up to toxic levels that spell the death of brain cells. But the new study shows that the process is anything but gradual, and that infection and toxicity are independent stages of the disease. Prions quickly build up in the brains of mice over the course of a month or two, Collinge and his colleagues found, peaking at about 100 million infectious particles per brain. © Society for Science & the Public 2000 - 2011

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Link ID: 15052 - Posted: 02.26.2011

Tiffany O'Callaghan Invasive biopsy is currently the only sure way to diagnose the degenerative neurological condition Creutzfeldt–Jakob Disease (CJD). But a highly sensitive assay could change that, providing a fast, accurate alternative for early diagnosis of this rare but deadly condition. In its most common form, known as sporadic CJD, the disease affects roughly one in a million people. Beginning in the 1990s, several cases of a variation of CJD known as vCJD were reported among people who had consumed beef from cows infected with another disease, bovine spongiform encephalopathy (BSE). The findings, published online in Nature Medicine1, also suggest that the assay — developed by microbiologist Ryuichiro Atarashi of Nagasaki University, Japan, and his team — could pave the way for the screening of broad sectors of the population. CJD is a prion disease, in which an isomer of a common protein known as the prion protein (PrP) takes on an abnormal shape and becomes an infectious variant called PrPSc. This variant is thought to trigger the subsequent malformation of other PrP proteins. Unlike their normal counterparts, PrPSc prions cannot be broken down, and instead accumulate — often clustering in brain tissue. The pockets of abnormal tissue that result cause brain tissue to develop a sponge-like appearance, and because prion conditions can be spread by affected humans or animals, the diseases are often referred to as transmissible spongiform encephalopathies (TSEs). Humans can be affected by several such conditions, while in addition to BSE in cows, there are several other such disorders among animals, including a condition called scrapie in sheep and hamsters. © 2011 Nature Publishing Group,

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Link ID: 14935 - Posted: 01.31.2011

by Debora MacKenzie You catch flu by inhaling germs – now it seems you can catch prion diseases that way too. Prions are misshapen proteins that cause brain degeneration in conditions such as mad cow disease and scrapie in animals, and Creutzfeldt–Jakob disease in humans. They can get into you if you eat infected meat or receive infected blood, but it was thought they couldn't spread through air. Now Adriano Aguzzi of the Swiss Federal Institute of Technology in Zurich reports that mice exposed for 10 minutes to aerosols containing as little as 2.5 per cent brain tissue from mice with scrapie all developed the disease within months. The prions didn't need processing by the immune system first, as some other research has suggested, but entered the brain directly through nasal nerves. "We were amazed at how efficiently they spread," says Aguzzi. He warns that this doesn't mean animals or people with prion diseases actually transmit them through the air: there have been no unexplained cases of disease transmission which suggested this. But workers in mills that process potentially infected carcasses may need more respiratory protection. Labs that test for prions routinely make 10 per cent suspensions of brain tissue, and any handling – pipetting, for example – creates aerosols. Prion labs are not required to use safety equipment that protects workers from aerosols. Aguzzi, who tested his aerosols at the highest level of protection, thinks those labs may now need to rethink safety measures. Journal reference: PLoS Pathogens, DOI: 10.1371/journal.ppat.1001257 © Copyright Reed Business Information Ltd.

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Link ID: 14873 - Posted: 01.15.2011

A fast test to diagnose fatal brain conditions such as mad cow disease in cattle and Creutzfeldt-Jakob disease in humans could be on the horizon, according to a new study from National Institutes of Health scientists. Researchers at NIH's National Institute of Allergy and Infectious Diseases (NIAID) have developed a highly sensitive and rapid new method to detect and measure infectious agents called prions that cause these diseases. Prion diseases are primarily brain-damaging conditions also known as transmissible spongiform encephalopathies. They are difficult to diagnose, untreatable and ultimately fatal. A key physical characteristic of these diseases is dead tissue that leaves sponge-like holes in the brain. Prion diseases include mad cow disease, or bovine spongiform encephalopathy in cattle; scrapie in sheep; Creutzfeldt-Jakob disease in humans; and chronic wasting disease in deer, elk and moose. For more information about NIAID research on prion diseases, visit the NIAID Prion Diseases portal (http://www.niaid.nih.gov/topics/prion/Pages/default.aspx). Currently available diagnostic tests lack the sensitivity, speed or quantitative capabilities required for many important applications in medicine, agriculture, wildlife biology and research. Because prion infections can be present for decades before disease symptoms appear, a better test might create the possibility for early treatment to stop the spread of disease and prevent death. Now, a blending of previous test concepts by the NIAID group has led to the development of a new prion detection method, called real time quaking induced conversion assay, or RT-QuIC. This approach is described in a paper now online in the open-access journal PLoS Pathogens. Byron Caughey, Ph.D., led the study at NIAID's Rocky Mountain Laboratories in Hamilton, Mont.

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Link ID: 14737 - Posted: 12.04.2010

by Amber Angelle For nearly 30 years, researchers have gathered evidence that a group of bizarre, fatal brain diseases—including mad cow and its human equivalent, Creutzfeldt-Jakob disease—are caused not by a virus or bacterium but by an abnormal form of a protein, called a prion. New studies lend the strongest support yet to this once-controversial idea and are also starting to reveal the beneficial natural functions these proteins perform before they go bad. Molecular biochemist Jiyan Ma at Ohio State University and colleagues were able to transform a normal protein produced by E. coli bacteria into a prion whose properties match those of the infectious version: It forms clumps, resists being cut by enzymes, and converts other normal proteins into the aberrant form. When the prion was injected into the brains of mice, the brains became spongy and riddled with holes, the telltale signs of prion disease. “Next we plan to take a closer look at the system we used to create infectious prions to identify the molecular mechanisms behind the change,” Ma says. In a separate experiment, researchers in the United States and Austria used a prion protein generated by E. coli to infect hamsters with a transmissible brain disease. The disease progressed very gradually, just as it does in humans, suggesting that the hamsters could provide a useful animal model system. Copyright © 2010, Kalmbach Publishing Co.

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Link ID: 14523 - Posted: 10.05.2010

by Roger Highfield Before winning his Nobel prize, Stanley Prusiner was ridiculed for suggesting that something he called a prion caused spongiform brain diseases WHEN the evidence suggested that the baffling "spongiform" brain disorders Creutzfeldt-Jakob disease (CJD), kuru and scrapie could not be transmitted by a virus or bacterium, the neurologist Stanley Prusiner put forward a novel type of infectious agent as the cause: a rogue protein. It was an idea considered so outrageous that Prusiner was ridiculed. Prusiner first began to study these diseases in 1972, after one of his patients at the University of California, San Francisco, died of CJD. A decade later, in the journal Science (vol 216, p 136), he suggested that these diseases were caused by a "proteinaceous infectious particle", or prion. The idea built on the findings of British researchers. In 1967, Tikvah Alper of the Medical Research Council's Radiopathology Unit showed that whatever it was that caused CJD was unscathed by levels of ultraviolet radiation that would destroy any genetic material (Nature, vol 214, p 764). Shortly afterwards, mathematician John Stanley Griffith of Bedford College in London devised a protein-only hypothesis for scrapie propagation. His 1967 Nature paper (vol 215, p 1043) states there was no reason to fear that the idea "would cause the whole theoretical structure of molecular biology to come tumbling down". © Copyright Reed Business Information Ltd.

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Link ID: 14464 - Posted: 09.18.2010

By Caroline Parkinson A new form of brain disease, similar to Creutzfeld-Jakob Disease, could affect more people than previously thought, researchers in the US say. It had been thought that only people with one genetic profile were vulnerable to the prion disease VPSPr. But in an Annals of Neurology study, Case Western Reserve University experts found people with all three possible gene patterns are affected by VPSPr. They say the findings could help with the treatment of prion diseases. Although it is a prion disease like vCJD, VPSPr is not linked to eating infected meat. However, like CJD, the new condition happens sporadically. It was first identified because of the fast-advancing form of dementia seen in those affected. They were also unable to speak or move. But tests for CJD proved negative. Further molecular examination showed VPSPr was a prion disease, but one which looked very different to those already known. The human prion protein gene comes in three variants, depending on which amino acid the prion proteins contain - valine (V) or methionine (M). People can be VV, MM or MV. The first clutch of cases identified all had the VV variant. However, these latest cases included people with the other variants too. Despite extensive research, a relatively large group of neurodegenerative diseases associated with dementia remain undefined. (C)BBC

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Link ID: 14359 - Posted: 08.14.2010

Daniel Cressey After an epic series of experiments, a group of researchers has observed and reproduced what could be the spontaneous generation of prions — rogue misfolded proteins that have been implicated in the destruction of the central nervous system. These misfolded proteins, the culprits in Creutzfeldt–Jakob disease and scrapie, are highly infectious. Although famously transmitted by the ingestion of infected meats, prions are also thought to arise spontaneously in a tiny fraction of humans and other animals. Such de novo prion generation has previously been achieved with animal cells using a method called 'protein misfolding cyclic amplification' (PMCA), which involves repeated rounds of ultrasound and incubation. Now, a London-based team reports observing prions appearing from healthy mouse brain tissue1. (Human samples have traditionally proved less amenable to PMCA, and the misfolding of prion proteins is believed to occur at a much lower rate in humans than in mice.) "What we were doing was trying to develop a very sensitive assay for prion detection on a metal surface, so we could use that in prion decontamination," says co-author John Collinge, who heads up the Department of Neurodegenerative Disease at University College London. "It took a while before we could convince ourselves this was a real phenomenon." © 2010 Nature Publishing Group

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Link ID: 14298 - Posted: 07.27.2010

By Laura Sanders Prion protein, notorious for causing the brain-wasting mad cow and Creutzfeldt-Jakob diseases, may also be a coconspirator in Alzheimer’s disease, a new study in mice suggests. In mad cow and Creutzfeldt-Jakob diseases, misshapen prion proteins do the damage. But the new paper, appearing February 26 in Nature, offers evidence that the harmless version of the prion protein assists the amyloid-beta protein responsible for brain cell death in Alzheimer’s disease. “It’s pretty sensational,” comments Adriano Aguzzi, a neuropathologist at the University of Zurich. “What’s tremendously electrifying is that prion protein may be a genetic sensor for extremely toxic, small concentrations of A-beta.” A-beta proteins can travel alone or in groups in the brain. On their own, A-beta proteins are harmless. Massive, insoluble clumps of A-beta, known as plaques, are probably harmless, too, says study coauthor Stephen Strittmatter, a neuroscientist at Yale University. These plaques may be a gravestone marker of dead brain cells but are probably not the killer. Instead, smaller, soluble clumps of 50 to 100 A-beta proteins, known as oligomers, are the most likely suspect, Strittmatter says. Earlier studies have shown that mice with A-beta oligomers can’t remember how to get through a maze as quickly as mice without A-beta oligomers. Such oligomers prevent cross-talk between certain brain cells in the hippocampus of mice, which helps explain the loss of learning and memory functions in Alzheimer’s disease. © Society for Science & the Public 2000 - 2009

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Link ID: 12594 - Posted: 06.24.2010

The US has found its second case of mad cow disease in a cow suspected, but cleared, of having BSE in November 2004. Although meat from the cow did not enter the food chain, the finding calls into question the accuracy of the country’s BSE surveillance programme. The cow might also be the first case born in the US. The first US case was in a cow imported from Canada in 2003. In 2004 the country started testing “high-risk” cattle - those that show neurological symptoms, are found dead or are “downers” (unable to stand). Since then it has tested 375,000 cattle. None were declared positive. In contrast, Canada has tested 30,000 cattle and found three positives. The rate at which the tests uncover positive cattle depends on the sample size, stresses Marcus Doherr of the University of Bern in Switzerland, who helped develop Swiss BSE surveillance. This means either that BSE is less evenly distributed in North America than thought, or that the US is missing cases. Unlike Canada, which uses the rapid “western blot” test, the US uses a test called ELISA, which is more prone to false positives. In 2004 the ELISA test detected three BSE positive cattle in the US. When these brains were re-tested, the ELISA was negative. Then they were subjected to immunohistochemistry (IHC) testing - a thin slice of brain is stained with antibodies for the prion protein that causes BSE. All were negative, and the cattle were declared BSE-free. “But if the prion is diffuse enough in the brain tissue, you can get a weak signal with the ELISA, and a negative with IHC,” says Doherr. Another test is needed to be certain, he says. © Copyright Reed Business Information Ltd

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Link ID: 7487 - Posted: 06.24.2010

Jim Schnabel Of all the ways that proteins can go bad, becoming an amyloid is surely one of the worst. In this state, sticky elements within proteins emerge and seed the growth of sometimes deadly fibrils. Amyloids riddle the brain in Alzheimer's disease and Creutzfeldt–Jakob disease. But until recently it has seemed that this corrupt state could threaten only a tiny fraction of proteins. Research is now hinting at a more unsettling picture. In work reported in February, a team led by David Eisenberg at the University of California, Los Angeles, sifted through tens of thousands of proteins looking for segments with the peculiar stickiness needed to form amyloid1. They found, says Eisenberg, that "effectively all complex proteins have these short segments that, if exposed and flexible enough, are capable of triggering amyloid formation". Not all proteins form amyloids, however. The 'amylome', as Eisenberg calls it, is restricted because most proteins hide these sticky segments out of harm's way or otherwise keep their stickiness under control. His results and other work suggest that evolution treats amyloids as a fundamental threat. Amyloids have been found in some of the most common age-related diseases, and there is evidence that ageing itself makes some amyloid accumulation inevitable. It now seems as though the human body is perched precariously above an amyloidal abyss. "The amyloid state is more like the default state of a protein, and in the absence of specific protective mechanisms, many of our proteins could fall into it," says Chris Dobson, a structural biologist at the University of Cambridge, UK. © 2010 Nature Publishing Group,

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Link ID: 13964 - Posted: 06.24.2010

Prions, the mis-folded proteins best known for causing diseases such as bovine spongiform encephalopathy in cows, scrapie in sheep and Creutzfeldt–Jakob disease in humans, could also help yeast survival, according to a study in the journal Cell1. "We think prions are really important," says co-author Simon Alberti of the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts. "When environmental conditions are harsh, they might allow a species to survive." The work, led by Susan Lindquist of the Whitehead Institute, bolsters the theory that prions might confer an evolutionary advantage, says Alberti. Lindquist first broached that idea nine years ago, after finding that a prion called PSI+ in the yeast Saccharomyces cerevisiae triggered heritable changes that could provide a way of adapting to fluctuating environments2. More recent work also suggests prions might play a role in memory in sea slugs and smell in mice. In the new work, a scan of the S. cerevisiae genome yielded 24 potential prion-forming proteins. Only five prions were known to exist in yeast before this study. The team focused on a protein called Mot3 and found that it can twist into a prion form. When in its normal shape, Mot3 suppresses yeast genes involved in building the cellular wall. But when Mot3 kinks into a prion, it loses this function and the wall-building genes activate. Hence, yeast carrying the Mot3 prions grew thicker, more robust cell walls. © 2009 Nature Publishing Group,

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Link ID: 12716 - Posted: 06.24.2010

Debora McKenzie Viruses, not prions, may be at the root of diseases such as scrapie, BSE and variant Creutzfeldt-Jakob disease (vCJD), researchers say. If true, the new theory could revolutionise our understanding of these so-called transmissible spongiform encephalopathies (TSEs), and potentially lead to new ways of treating them. The widely accepted theory of what causes infectious prion diseases – such as vCJD, scrapie and “mad cow disease” – is that deformed proteins called prions corrupt other brain proteins, eventually clogging and destroying brain cells. However, this theory has not been definitively proven. Laura Manuelidis at Yale University in New Haven, Connecticut, US, has insisted for years that tiny virus-like particles observed in TSE-infected brains may be the culprits. But such brains are degenerating, so the particles had been dismissed as general debris. When Manuelidis studied cultures of neural cells infected with two particular strains of scrapie and CJD, she found that these virus-like particles were clustered in regular arrays within the cells – in a pattern that viruses regularly form in cells – and she saw no apparent prions in the cells. © Copyright Reed Business Information Ltd.

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Link ID: 9956 - Posted: 06.24.2010

Stu Hutson The curative properties of stem cells may rely on prions, a new study suggests, the type of protein made infamous by mad cow disease. Prions are a special class of protein that can change the shape and function of other proteins around them. While these are found throughout any mammal’s body, the understanding of their biological role is limited. What is known is that prions that become misshapen, through some unknown process, can result in BSE (bovine spongiform encephalopathy) – mad cow disease – and its equivalents in other animals. Researchers at the Whitehead Institute in Cambridge, Massachusetts, US, have now found that adult stem cells in bone marrow gradually lose their ability to regenerate without their normal complement of membrane-bound prions. Stem cells are primitive cells which have the potential to divide endlessly, and the ability to differentiate into any cell type in the body – offering hope for future therapies. Andrew Steele, Cheng Cheng Zhang and colleagues used radiation to deplete the bone marrow of mice genetically engineered to not produce the prion proteins. The animals’ marrow regenerated quickly at first, but eventually slowed to a stop. The marrow also lost its regenerative abilities when transplanted into normal mice. © Copyright Reed Business Information Ltd

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Link ID: 8461 - Posted: 06.24.2010

Debora MacKenzie The infectious prions that cause Chronic Wasting Disease, an infection similar to BSE that afflicts North American deer and elk have been found in the parts of the animals that people eat. No one knows if CWD can jump to humans, but if it does hunters in affected areas might be at risk. CWD was first diagnosed as a spongiform encephalopathy in captive deer and elk in Colorado in the 1970s, and in wild deer and elk in the region in the 1980s. But in the 1990s it spread widely within the elk farming industry, jumped to wild deer, and now affects two provinces of Canada and 13 US states. Like the related sheep disease scrapie – though unlike BSE – CWD spreads from animal to animal, says Glenn Telling of the University of Kentucky at Lexington, US. Deer housed with infected animals, or fed infected brain experimentally, contract the disease. Because of this there are fears that the CWD prion might be distributed widely in the deer’s tissues – as scrapie is in sheep. Efforts to find the infectious prion in the muscle of infected animals, by seeing whether antibodies to the prion could find any and bind on, have previously failed. But Telling’s lab has now shown that diseased prions can reside in muscle of deer infected with CWD, by using transgenic mice. © Copyright Reed Business Information Ltd.

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Link ID: 8450 - Posted: 06.24.2010

Study reveals antibodies can kill brain cells. HELEN PEARSON Antibody therapies designed to treat the human form of mad cow disease could backfire, warn US scientists. The group investigated the proteins called prions that cause the rare brain disorder variant Creutzfeldt–Jakob disease (vCJD) and its farmyard equivalent, bovine spongiform encephalopathy (BSE). Prions cause disease when they take on a misshapen form, accumulate in the brain and kill off nerve cells. Some research groups are trying to prevent this by using antibodies that grab hold of normal prions and prevent them from transforming into the harmful configuration. © Nature News Service / Macmillan Magazines Ltd 2003

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Link ID: 4888 - Posted: 06.24.2010

Research by North Carolina State University scientists, in conjunction with scientists from the Netherlands and BioResource International, an NC State spin-off biotechnology company, has shown that, under proper conditions, an enzyme can fully degrade the prion – or protein particle – believed to be responsible for mad cow disease and other related animal and human diseases. These transmissible prions – believed to be the cause of bovine spongiform encephalopathy (BSE), the technical name for mad cow disease, as well as the human and sheep versions, called Creutzfeldt-Jakob disease and scrapie, respectively – are highly resistant to degradation, says Dr. Jason Shih, professor of biotechnology and poultry science at NC State. But the new research, which tested the effects of a bacterial enzyme keratinase on brain tissues from cows with BSE and sheep with scrapie, showed that, when the tissue was pretreated and in the presence of a detergent, the enzyme fully degraded the prion, rendering it undetectable. The research was published in the Dec. 1 edition of The Journal of Infectious Diseases.

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Link ID: 4757 - Posted: 06.24.2010