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HOOF-prints help find where outbreaks begin

Locating potential sources of brucellosis outbreaks is easier now, thanks to a new DNA fingerprinting technique developed by scientists with the Agricultural Research Service (ARS) and the Animal and Plant Health Inspection Service (APHIS). A new DNA fingerprinting technique called HOOF-Prints can identify strains of Brucella bacteria. Brucellosis induces abortions in many animals including elk, sheep, goats, cattle, pigs and bison. Finding the source of these outbreaks helps with identification and isolation of infected animals, and with telling whether the outbreaks started in wildlife, according to microbiologists Betsy Bricker at ARS’ National Animal Disease Center and Darla Ewalt of APHIS’ National Veterinary Services Laboratories, both in Ames, Iowa.

The new technique — called “HOOF-Prints,” for Hypervariable Octameric Oligonucleotide Fingerprints — allows scientists to identify strains of brucellosis through differences in their DNA sequences, and to separate these strains into subtypes. Brucellosis is an extremely infectious disease caused by Brucella bacteria that induce abortions in many animals, including sheep, goats, cattle, pigs, elk and bison. Humans who come in contact with Brucella can get undulant fever, which is marked by chronic flulike symptoms.

Though almost eradicated from the United States, brucellosis can still prove costly to livestock producers through testing and losses. Outbreaks may cause states to lose brucellosis-free status, meaning their cattle must undergo extensive testing before they can be shipped away. The new method uses polymerase chain reaction (PCR) technology, which copies large amounts of DNA molecules from small amounts of source DNA. According to Ewalt, the HOOF-Prints technique is intended to complement existing PCR and bacteriological tests used to identify Brucella species. HOOF-Prints was first applied in the field in 2002 when it was used to trace a brucellosis outbreak in Fremont County, Idaho, cattle to local elk. It could eventually be applied toward generating an international database of Brucella fingerprints that would be used to control the disease, according to Bricker.

Science Daily
February 28, 2006

Original web page at Science Daily

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Medication for endangered vultures offers hope

Scientists have offered a ray of hope to Asian vultures being wiped out in India after eating the corpses of cattle treated with a common anti-inflammatory drug. And they called on the Indian government, which has already banned the use of the drug diclofenac, to intensify a captive breeding program for threatened Oriental white-backed, long-billed and slender-billed vultures. In the journal PLoS Biology, the scientists from Britain, India, South Africa and Namibia said diclofenac — which is fatal to the birds — could readily be replaced by meloxicam which is not. “We conclude that meloxicam is of low toxicity to (the) vultures and that its use in place of diclofenac would reduce vulture mortality in the Indian subcontinent,” they wrote.

The scientists noted that the populations in South Asia of the three threatened vultures had plummeted by more than 97 percent over the past 15 years due to the widespread use of diclofenac to treat sick cattle. Birds eating the carcass of an animal that had died shortly after treatment with the drug suffered kidney damage, increased serum uric acid concentrations, visceral gout and death. But trials in South Africa and Namibia had shown that vultures suffered no ill effects when fed even high doses of meloxicam which was as effective in cattle as diclofenac.

“We recommend that governments consider advocating the use of meloxicam as an alternative to diclofenac,” the scientists wrote. “Because vulture populations are now very low and contamination of even a small proportion of livestock carcasses is sufficient to cause adverse impacts on vulture populations, we also advocate immediate intensification of efforts to establish viable captive breeding populations,” they added. Debbie Pain, head of international research at Britain’s Royal Society for the Protection of Birds and co-author of the paper, welcomed the rapid results after diclofenac was found to be the culprit just two years ago. “This research is an excellent example of international collaboration in response to an urgent conservation problem,” she said.

Reuters
February 14, 2006

Original web page at Reuters

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China produces 6th recloned calf

Scientists in China say they have successfully produced another calf cloned from the cells of cloned cattle. The project run jointly by the China Agriculture University in Beijing and the Shandong Kelong Animal Husbandry Co. Ltd. in Shandong Province has now produced six recloned calves that are still alive, Xinhua, the official government news agency, reported. All were produced from ear cells of cloned cows selected for their high mammary gland expression.

Two calves died soon after birth

Science Daily
January 17, 2006

Original web page at Science Daily

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Cloned, fertilized embryos look alike

Researchers have shown that cloned embryos undergo complete nuclear reprogramming and resemble fertilized embryos. The report, appearing in the December 6 issue of Proceedings of the National Academy of Science, appears to refute the long-held belief that the high failure rate of cloning is due to faulty nuclear reprogramming of the donor cell nucleus to an embryonic state. Researchers suggest that the findings may only deepen the mystery of why cloning often fails, and demonstrate how far scientists have to go before improving the process. “It’s a surprising result that reprogramming obviously works very nicely,” Heiner Niemann at the Institute for Animal Breeding in Neustadt-Mariensee, Germany, told The Scientist.

Thirteen mammal species have been successfully cloned to date, but only 1-5% of cloned embryos ever produce live young, regardless of species. In the current study, Xiangzhong “Jerry” Yang, at the University of Connecticut, Storrs, Ct., along with colleagues at the University of Illinois in Urbana, Il. and the National Institute for Agricultural Research (INRA) in France, used cDNA microarray analysis to determine if abnormal gene expression among cloned embryos could explain why cloning often fails. “Many papers have looked at a few genes, but this is the first time anyone has looked at a large number of genes,” said Eckhard Wolf, at Ludwig-Maximilian University in Munich, Germany. The researchers compared the gene expression profiles of cow embryos obtained by artificial insemination (AI), in vitro fertilization (IVF), and somatic (donor) cell nuclear transfer (NT), in which the nucleus of a donor cell is transferred into an egg cell whose nucleus has been removed.

One week after cloning (blastocyst stage), NT embryo expression profiles differed completely from the donor cells used to create them, indicating that nuclear reprogramming had been successful. “What was shocking to us was that the cloned embryos were more similar to naturally fertilized embryos – and among cloned embryos, there was very little difference” between them, Yang told The Scientist. Furthermore, the NT embryos resembled AI embryos much more closely than IVF embryos.

Using bovine microarrays developed by colleagues at the University of Illinois, the researchers found that less than 1% of 5000 genes analyzed differed more than two-fold between NT and AI embryos – comparable to differences observed between genetically unrelated AI embryos. However, 25 genes were uniquely expressed in the NT embryos. “We want to extensively study these genes and see if they are responsible for the later reprogramming problems,” said Yang. He added that cloning problems may happen at a later stage during differentiation. Niemann cautioned that these are early findings. “I would anticipate 8000-10000 genes involved in” fetal development, said Niemann. “We will learn more about critical genes involved when we have complete bovine genome arrays.” Wolf agreed that further studies are needed. “We cannot conclude that cloned blastocysts are more normal than IVF blastocysts because there was a lot of genetic variability in the IVF group,” he said.

These findings don’t bode well for those hoping to see stem cell therapy a reality anytime soon either, according to Wolf Reik, at the Babraham Institute in Cambridge, U.K. “Even if cloned embryos are born, many are not normal and die prematurely – these late effects are not caused by early deficits in gene expression, and that’s what this study shows,” said Reik. Consequently, stem cells used therapeutically may appear perfectly normal initially, with problems arising only later, he cautioned. “This study clearly indicates that technical improvements cannot overcome the post-implantation problems of clones,” Atsuo Ogura, at the Riken Bioresource Center in Tsukuba-shi, Ibaraki, Japan, told The Scientist. “It reminds us of the fact that no eventual progress has been made in cloning efficiencies in the 10 years since Dolly the sheep was born.”

The Scientist
December 20, 2005

Original web page at The Scientist

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Retinal scans eyed for New Mexico show cattle

It sounds like science fiction, but New Mexico State University researchers are testing advanced eye-scanning technology on cattle as part of a national tracking system for animal health. “Retinal scans are part of a growing technological trend in cattle identification,” said Manny Encinias, livestock specialist at NMSU’s Clayton Livestock Research Center. “It painlessly flashes a beam of light into the eyeball and records the pattern of veins in the eye.” Each retina, whether bovine or human, is unique and a scan is considered one of the most accurate forms of identification, he said.

The NMSU evaluations are part of an accelerating effort by the U.S. Department of Agriculture to implement a National Animal Identification System. The goal is to track and identify all animals and premises that have had contact with an animal disease of concern within 48 hours of an initial diagnosis. In a first-of-its kind project for New Mexico, scientists tested 35 market steers from 18 Quay County farm families, using a combination of eye-scanning and radio frequency identification (RFID) ear tags for animal ID evaluation. Most of the cattle were high-value 4-H and FFA show cattle that spent much of the past season moving between regional livestock fairs.

Encinias used a $3,000 retinal scanner not much bigger than a small video camera to record the IDs at three locations over a six-month period. To make the digital record, the cow is held in what’s known as a squeeze chute and the scanner’s eye-cup, specially molded for a cow’s face, is held to each animal’s eye. The scanner senses when the eye is open, automatically makes an image, and downloads the data to a computer database. In addition to the retinal image, the device records the date, time and a global positioning satellite coordinate of the location. “It’s as simple as taking a picture,” Encinias said. “Plus, we can do everything at chute side.”

Historically, 4-H and FFA exhibitors have been required to submit hair samples for DNA analysis to serve as a permanent means of identification. “DNA analysis is costly and requires a complex laboratory procedure that takes time,” he said. “Also, hair samples have been lost in transit.” Among the show cattle, researchers found that the retinal scans proved a near-perfect animal ID technology because of its speed and accuracy, Encinias said. However, the eye-scans might not be practical on a working ranch due to cost and technical skill required. Separately, NMSU experts examined RFID tags alone on several hundred cattle on a communal grazing allotment in the Valles Caldera, an 89,000-acre area in the Jemez Mountains. Communal grazing allotments are typically seasonal, running from May to October. “We wanted to show the small-scale producers of northern and central New Mexico that this animal ID technology will work for them, too,” Encinias said.

The $2 tags contain a unique 15-digit electronic code identifying each animal like a Social Security number for life. Located on the cow’s left ear, the tags are about the size of a bottle cap. With more than 900 RFID tags applied since May, only two have been lost. Using a panel tag reader located on a cattle chute, researchers found that the RFID tags could be readily read as cattle passed through a single-file alley. Effective range for this particular electronic reader was about two feet. “A prime goal was not to slow down the normal production process, and I think we did that,” he said. “We maintained a single-file, continuous flow with a reliability rate of more than 93 percent. It’s not 100 percent, and that’s something we’re working on.”

The animal ID projects, which were conducted in cooperation with the state veterinarian’s office and the New Mexico Livestock Board, were funded through a USDA grant, and were designed to evaluate the technology specifically for New Mexico’s varied production environments. “We need to have producers on board and comfortable with ID technology because it’s inevitable that it’s coming to New Mexico,” Encinias said. When the idea of mandatory cattle identification was introduced several years ago, cattle producers were concerned about expense, inconvenience and loss of privacy.

But experts stress the importance of controlling cattle diseases before they get out of hand, said Clay Mathis, a livestock specialist with NMSU’s Cooperative Extension Service. Even though the new system will cost producers more money, it will eventually mean the full tracking of animal movement throughout the nation, he said. The announced USDA target for a mandatory animal identification program is January 2009, said Ron Parker, an animal ID specialist with NMSU Extension and the New Mexico Livestock Board. At that time, all animals entering marketing channels must be identified. Now, a final report on both NMSU animal ID technology studies is being compiled for USDA, Encinias said. “In the future, we need to look at just how long the RFID tags last under New Mexico’s varied and sometimes brutal climate conditions,” he said. “And, we need to see how these ID technologies work at the sale barn and other commingling areas.”

Science Daily
December 6, 2005

Original web page at Science Daily

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Cattle grazing may help rather than hurt endangered species

An article published in the latest issue of Conservation Biology finds that cattle-grazing plays an important role in maintaining wetland habitat necessary for some endangered species. Removing cattle from grazing lands in the Central Valley of California could, inadvertently, degrade the vernal pool habitat of fairy shrimp and tiger salamanders. Cattle-grazing influences the rates of evaporation which work together with climate to determine the depth and duration of wetland flooding. Cattle have been grazing in the land for roughly 150 years and have become a naturalized part of the ecosystem. “In practical terms, this means that grazing may help sustain the kinds of aquatic environments endangered fairy shrimps need to survive,” author Christopher R. Pyke states.

The authors looked at 36 vernal pools on two different geologic formations on a 5000-ha ranch in eastern Sacramento County, California. Their experiments found that removal of grazing reduced the duration of wetland flooding by an average of 50 days per year. Their simulations show that climate change could compound these impacts, potentially, leaving endangered fairy shrimp and tiger salamanders without enough time to mature before their temporary aquatic environments disappear. “Consequently, land managers can play an important role in climate change impacts, i.e. they can exacerbate or ameliorate, the local impacts of global change.” Pyke adds. Conservationists may find that grazing is not always a negative factor, and it presents real opportunities to adapt to climate variability and climate change.

Science Daily
November 8, 2005

Original web page at Science Daily

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Government consults on lifting BSE export ban

The Government today began a consultation on expected changes to UK legislation to lift the EU ban on the export of beef, bovine products and live cattle. The consultation also deals with consequential changes to controls on Specified Risk Materials (SRM). The timing of lifting the export ban remains uncertain. The Government cannot be sure whether or when the European Commission and EU Member States will agree to lift the ban but this is unlikely to happen before February 2006 at the earliest. The Commission would first need to make a proposal to lift the ban to Member States who would then need to agree the proposal. The Government is continuing to work in Brussels to ensure that the export ban is lifted as soon as possible. The consultation is being issued in advance of a Commission proposal so that the UK is ready to amend our domestic UK legislation as soon as possible if and after EU legislation is amended. When the ban is lifted, the UK expects to be able to export beef and bovine products from cattle born after July 1996 on the same basis as other EU member States. The UK would also be able to export live cattle born after July 1996 on the same basis as other Member States. Cattle born or reared in the UK before August 1996 will remain permanently excluded from the food chain.

When the export ban is lifted, the UK will need to come into line with controls that apply in other Member States. This will mean that for a new sector of the UK cattle population, that is for all cattle slaughtered when they are aged over 24 months to 30 months, the vertebral column must be removed and destroyed as SRM. Currently, the UK does not have to remove vertebral column except in cattle aged over 30 months. About 50% of UK cattle are currently slaughtered for human consumption aged less than 24 months. Arrangements for cattle aged 24 months or less would be unaffected by a change in the SRM age threshold.

The vertebral column of cattle aged over 30 months would continue to be removed in licensed cutting plants but the consultation seeks views on whether the UK should allow vertebral column from cattle aged 24 – 30 months also to be removed in specifically authorised butcher’s shops. This would enable butchers to continue to bone out beef from cattle of this age in their shops. The other significant expected change is that the UK would again be allowed to remove meat from the heads of cattle for human consumption. Views are also sought on whether the UK should allow this to take place in specifically authorised cutting plants as well as in abattoirs.

WVA
November 8, 2005

Original web page at Defra. UK

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‘Mad cow’ proteins successfully detected in blood

Researchers at the University of Texas Medical Branch at Galveston (UTMB) have found a way to detect in blood the malformed proteins that cause “mad cow disease,” the first time such “prions” have been detected biochemically in blood. The discovery, reported in an article online in Nature Medicine is expected to lead to a much more effective detection method for the infectious proteins responsible for brain-destroying disorders, such as bovine spongiform encephalopathy (BSE) in cattle and variant Creutzfeldt-Jakob disease (vCJD) in humans. The blood test would make it much easier to keep BSE-infected beef out of the human food supply, ensure that blood transfusions and organ transplants do not transmit vCJD, and give researchers their first chance to figure out how many people may be incubating the disease.

“The concentration of infectious prion protein in blood is far too small to be detected by the methods used to detect it in the brain, but we know it’s still enough to spread the disease,” said UTMB neurology professor Claudio Soto, senior author of the Nature Medicine paper. “The key to our success was developing a technique that would amplify the quantity of this protein more than 10 million-fold, raising it to a detectable level.” Soto and the paper’s other authors, UTMB assistant professor of neurology Joaquin Castilla and research assistant Paula Saá, applied a method they call protein misfolding cyclic amplification (PMCA) to blood samples taken from 18 prion-infected hamsters that had developed clinical symptoms of prion disease. PMCA uses sound waves to vastly accelerate the process that prions use to convert normal proteins to misshapen infectious forms.

Successive rounds of PMCA led to the discovery of prions in the blood of 16 of the 18 infected hamsters. No prions were found in blood samples that were taken from 12 healthy control hamsters and subjected to the same treatment. “Since the original publication of a paper on our PMCA technology, we’ve spent four years optimizing and automating this process to get to this point,” Soto said. “The next step, which we’re currently working on, will be detecting prions in the blood of animals before they develop clinical symptoms and applying the technology to human blood samples.”

Tests for infectious prions in cattle and human blood are badly needed. Because current tests require post-slaughter brain tissue for analysis, in the United States only cattle already showing clinical symptoms of BSE (so-called “downer cows”) are tested for the disorder. This is true even though vCJD potentially can be transmitted by animals not yet showing symptoms of the disease. (Only two cases of BSE have been found in American cows so far.) And although British BSE cases have been in decline since 1992, scientists believe the British BSE epidemic of the 1980s could have exposed millions of people in the UK and Europe to infectious prions. The extent of the vCJD epidemic is yet unknown. So far the disease has killed around 180 people worldwide, but numbers could reach thousands or even hundreds of thousands in the coming decades. Prions have also been shown to be transmissible through blood transfusions and organ transplants.

“Who knows what the real situation is in cattle in the United States? And with people, we could be sitting on a time bomb, because the incubation period of this disease in humans can be up to 40 years,” Soto said. “That’s why a blood test is so important. We need to know the extent of the problem, we need to make sure that beef and the human blood supply are safe, and we need early diagnosis so that when scientists develop a therapy we can intervene before clinical symptoms appear–by then, it’s too late.”

Science Daily
October 11, 2005

Original web page at Science Daily

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A live-animal test for BSE?

Since May 2003, three cases of the prion disease have been found in Canadian cattle, prompting 34 countries to slam their doors to Canadian beef. Though about half have relented, the industry still lost more than $5.8 billion (US), largely in live-animal exports. Because there is currently no reliable way to test an animal for bovine spongiform encephalopathy (BSE) antemortem, farmers with diseased animals must destroy entire herds. A live-animal test could thus prevent the needless slaughter of healthy animals – and reduce potential losses.

Two recent events suggest such a test could be forthcoming. First, Calgary-based Vacci-Test announced June 16 it would begin offering a live-animal field test by autumn. More recently, researchers at the University of Texas Medical Branch at Galveston (UTMB) reported a test to detect prions in blood samples. UTMB neurology professor Claudio Soto and colleagues used sound waves to accelerate the process prions use to convert normal proteins to misshapen infectious forms, in serum samples from prion-infected hamsters. The process, protein misfolding cyclic amplification (PMCA), is conceptually analogous to DNA amplification by PCR. Soto’s team used the process to amplify infectious prion protein more than 10 million-fold, detecting as few as 8,000 particles. The next step will be detecting prions in the blood of asymptomatic animals and applying the technology to human blood samples; something that will likely happen within a year, Soto says. “It is very possible to be implemented into a large-scale detection system that can be used for screening, for example, every single blood unit, to make sure they don’t have prions,” he adds.

Vacci-Test, on the other hand, claims its live-animal diagnostic is ready to go. Validation data based on 2,000 unidentified blood samples obtained from reference labs in the United Kingdom and France is being submitted to European authorities. Company president Bill Hogan expects the test will cost under $20 per animal. (Bio-Rad Laboratories’ postmortem tests, says company spokesperson Susan Berg, cost between $6 and $8 each.) Unlike other tests, which test for the presence of the prion particle itself, Vacci-Test checks for the presence of protein 14-3-3, a marker for neuronal injury in the central nervous system. “The disease is not in the blood, the marker is in the blood,” Hogan explains.

Transmissible spongiform encephalopathy (TSE) expert, Jacques Grassi, head of the Pharmacology and Immunology Unit of the French Atomic Energy Commission (CEA), is skeptical. “For me, it is nothing. I don’t know [the inventors, Jacques Mayet and Louis Léry]. No data has been published, not even on their Web site.” Besides, adds Bio-Rad’s Guillaume Camard, “A live test might be fine for surveillance, but what we want to know is that when a cow arrives at a slaughterhouse, can the meat can go into the food chain? If you didn’t test the animal right at the very end, specifically for BSE, you cannot get a true answer.”

Terry McElwain, executive director of the Washington Animal Disease Diagnostic Laboratory in Pullman, cites other concerns. BSE infection occurs primarily at a young age, with an incubation period of around four years, he says. “But you have to ask yourself, where is the infective agent during that four-year period and how do you validate that test on a population basis… before the animals develop any clinical brain disease?” And, he adds, “How do you know, when the 14-3-3 marker is not there, that the animal is truly negative?”

Jean-Philippe Deslys, who coordinates NeuroPrion, the world’s largest prion disease research network, is another skeptic. Several groups are getting close to a live-animal test, he says, but “I think we still have a lot of work to do before having something practicable for the field.” That, says Deslys, could take another two years, though he says “the first real results” could be announced at Prion 2005 (Dusseldorf, Germany) in October.

According to Koen Van Dyck, head of the TSE section, European Commission Health and Consumer Protection Directorate General, at least one other company is also in the hunt. “One antemortem [test] was selected for participation in… laboratory evaluation, and this evaluation is still ongoing,” Van Dyck writes via E-mail. He declined to reveal details, but says the test’s sponsor is a German company.

Whether any of these assays actually prove effective remains to be seen, but other companies have claimed to be on the verge of a live-animal test only to fail. A year ago, for instance, GeneThera was optimistic; today, the company’s Web site bears no mention of such a test. (The company did not respond to interview requests.) Says Grassi, “There are a lot of claims but, believe me, nothing has actually been demonstrated. As far as I know there is none that has been validated,” which makes the Texas team’s results all the more interesting. “We have been inundated with requests from companies and venture capital groups,” Soto says.

The Scientist
October 11, 2005

Original web page at The Scientist

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Did British cows eat remains of humans with brain disease?

Human remains in cattle feed could have caused the first case of mad cow disease, two UK researchers propose. The hypothesis seeks to answer lingering questions about the fatal infection, which has affected 180,000 cows in Britain alone since the mid-1980s, and has gone on to cause more than 100 deaths in humans. Alan Colchester of the University of Kent and his daughter Nancy Colchester, of the University of Edinburgh, point out that during the 1960s and 1970s Britain imported hundreds of thousands of tonnes of whole and crushed bones and animal carcasses. These were used for fertilizer and to feed livestock. Nearly 50% of these imports came from Bangladesh, where peasants gathering animal materials may have also picked up human remains, the researchers say.

Other experts in the field view the idea with scepticism, saying that proof remains circumstantial. “The argument isn’t very compelling because there’s no smoking gun evidence,” says Surachai Supattapone, an expert in infectious diseases at Dartmouth Medical School in Hanover, New Hampshire. Transmissible spongiform encephalopathies (TSEs) are a group of fatal neurodegenerative diseases that affect mammals. Yet until 1986 no such illness had been spotted in cattle. Once recognized, bovine spongiform encephalopathy (BSE) became widely known as ‘mad cow disease’. The incidence of the disease then rocketed, peaking in late 1992.

Tests indicated misshapen prion proteins in the brains of the cows as the source of the problem. And when authorities banned the practice of recycling animal remains into cattle feed the number of sick livestock began to drop. But experts continue to puzzle over how BSE arose in the first place. One of the most widely believed theories is that prions responsible for sheep scrapie got incorporated into cattle feed. Scientists argue that ingested scrapie prions radically altered the normal, analogous proteins in one cow, which then developed the first case of BSE. But the Colchesters point out that cows have been exposed to scrapie for 70 years, so it is hard to explain why BSE emerged only recently.

They propose that a more likely source is recent exposure to human remains carrying sporadic Creutzfeldt-Jakob Disease (CJD), a TSE thought to arise spontaneously in people. Religious customs in Bangladesh and surrounding areas mean that many corpses are disposed of in rivers. People may have collected remnants from such bodies when foraging for animal carcasses, the Colchesters argue in The Lancet. Any prions in these corpses might then have caused mad cow disease. Experts agree that the theory needs to be checked. More information needs to be collected, they say, about the number of deaths from CJD in the Indian subcontinent, what happened to the bodies, and whether prions could have been transmitted in the way proposed. When human sporadic CJD prions were injected into mice in previous studies, the mice did not become ill.

Nature
September 27, 2005

Original web page at Nature

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West African food crisis looming

According to recent estimates*, the Sahel region as a whole registered a grain surplus of 85 000 tonnes, but Niger and Chad suffered grain deficits of around 224 000 and 217 000 tonnes, respectively. An increase in food prices is fuelling the food crisis, especially in Mali, Mauritania and Niger, where millions of people are at risk of food shortages. “The situation is getting worse in the affected areas and unless aid comes now, hundred of thousands of people will be suffering the consequences for years to come. Farmers and herders who have lost their livelihoods because of drought and the locust invasion are living in poverty with very limited access to food,” said Fernanda Guerrieri, Chief of FAO’s Emergency Operations Service.

Fortunately, the Desert Locust situation is expected to remain relatively calm this summer in West Africa and, contrary to last year, swarms from Northwest Africa are not likely to invade the region this year. In the most affected areas in Mali, Mauritania and Niger, access to food staples is increasingly difficult and severe child malnutrition is reported to be on the rise. The scarcity of water and fodder is seriously affecting the health of the cattle, camels, sheep and goats that are the only source of food and income for nomadic communities. Competition for limited resources has sometimes resulted in local conflicts.

Farmers need seeds and agricultural inputs immediately to ensure the October 2005 harvest. Herders depend on animal feed distributions and veterinary services to keep their weakened animals alive. FAO has appealed for $11.4 million for emergency projects in the region. Projects in some countries are already operational but more funds are urgently needed. In the capital, Nouakchott, 18 000 people are benefiting directly from the distribution of vegetable seeds, which have been planted in plots reclaimed from the desert by farming cooperatives. Favourable climatic conditions permit up to four harvests per year, so the cooperatives are providing a constant source of vegetables for the town’s inhabitants, as well as helping to prevent further desertification.

In southern Mauritania, the distribution of animal feed and the provision of veterinary services will help keep animals alive until the rains come. Veterinarians are providing assistance to approximately 20 000 herders by examining and treating their animals when they come to drink at watering holes in the region.

E-mail address Bloglet
July 5, 2005

Original web page at WVA

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Variant prion protein causes infection but no symptoms

Abnormal prion proteins are little understood disease agents involved in causing horrific brain-wasting diseases such as Creutzfeldt-Jacob disease in people, mad cow disease in cattle and chronic wasting disease in deer and elk. Now, new research suggests that a variant form of abnormal prion protein–one lacking an “anchor” into the cell membrane–may be unable to signal cells to start the lethal disease process, according to scientists at the Rocky Mountain Laboratories (RML), part of the National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health.

“This work provides novel insights into how prion and other neurodegenerative diseases develop and it provides tantalizing clues as to how we might delay or even prevent such diseases by preventing certain cellular interactions,” notes NIAID Director Anthony S. Fauci, M.D. A paper describing the research was released online by the journal Science. RML virologist Bruce Chesebro, M.D., directed the project.

Drawing on experimental concepts first developed at RML a decade ago, the research team exposed two groups of 6-week-old mice to different strains of the agent that causes scrapie, a brain-wasting disease of sheep. Within 150 days of being inoculated with the natural form of scrapie prion protein, all 70 mice in the control group showed visible signs of infection: twitching, emaciation and poor coordination. In contrast, the scientists observed 128 transgenic mice–those engineered to produce prion protein without a glycophosphoinositol (GPI) cell membrane anchor–for 500 to 600 days and saw no signs of scrapie disease.
Subsequent electron microscopic examinations at UCSD, however, confirmed that they produced amyloid fibrils, an abnormal form of prion protein, and that they even had brain lesions. More remarkably, according to Dr. Chesebro, the diseased brain tissue resembled that found in Alzheimer’s disease rather than in scrapie.

Chesebro mentions two theories as to why the transgenic mice did not show symptoms of illness despite being infected: The host cell might require the GPI anchor to receive the “toxic signal” from the abnormal prion protein, or the plaques might be less toxic than the non-plaque form of prion protein clumps. In either case, more time might be required to produce disease due to the reduced toxicity, Dr. Chesebro says.

“There was so much about this research that surprised us and gave us ideas to pursue,” says Dr. Chesebro. “First, the mice didn’t get sick. That’s very significant. Second, the dense accumulations of scrapie plaque in the brain resembled the plaque seen in Alzheimer’s, but it wasn’t toxic,” which might support more recent concepts about plaque in Alzheimer’s patients. “Previously, most researchers thought plaques were the toxic component of Alzheimer’s that kills neurons, and many treatments focus on removing the plaques. But what if the plaques are inert, as they were in this research? What if only small clumps are toxic?”

If this hypothesis proves correct, Dr. Chesebro says, the ongoing research could eventually alter scientists’ views on preventing prion diseases, shifting emphasis away from stopping the production of prion protein clumps and toward preventing interactions with prion protein anchored to cells, or learning to direct abnormal prion protein accumulations to specific parts of the brain where they will not produce symptoms. “Abnormal prion protein by itself may not be rapidly lethal–in these mice it wasn’t,” Dr. Chesebro says.

Source: NIH/National Institute of Allergy and Infectious Diseases

Bio.com
June 21, 2005

Original web page at Bio.com

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China reports 2 outbreaks of foot and mouth disease

China has confirmed 2 outbreaks of foot and mouth disease in a rare acknowledgement that the problem even exists inside its borders, an international animal health organization said Sunday. More than 200 head of cattle were destroyed after the outbreaks were discovered, both in the eastern part of the country, the World Organization of Animal Health said. China’s Agriculture Ministry reported the 2 outbreaks, according to the organization. Both outbreaks happened during April 2005. One was in Wuxi city, Jiangsu province, where 15 cases were found and 183 animals destroyed. The other was in Tai’an city of Shandong province, where 17 cases were diagnosed and 40 head of cattle were destroyed, it said.

China has previously said instances of foot and mouth disease are relatively rare, but some critics have argued outbreaks happen at much greater frequency than admitted by the authorities. One of the only recent outbreaks to have been recognized by China’s animal health authorities was in Tibet in 1999. Outside observers suspect the country of being the origin of several foot-and-mouth epidemics in recent years, including a 1997 outbreak in Taiwan which was the 1st to strike the island in 68 years. Foot-and mouth disease is a severe, highly contagious viral disease affecting cattle, pigs, sheep and other livestock. It is not usually fatal but causes severe losses in the production of meat and milk. China’s willingness to impose transparency in its health bureaucracy was severely tested 2 years ago, during the outbreak of Severe Acute Respiratory Syndrome (SARS), a lung disease affecting humans. China initially claimed it did not have a major SARS epidemic on its hands. Global pressure eventually forced it to face up to the extent of the problem and admit it was the worst-hit country in the world.

In 2004, suspicions emerged that China was suffering from a similar lack of transparency in its animal health bureaucracy, following the regional outbreak of bird flu. China admitted to having experienced outbreaks of bird flu, but denied any people had died from it.

ProMed Mail
June 7, 2005

Original web page at Promed Mail

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Prion hypothesis proven?

Protein aggregates generated in a test tube infected wildtype hamsters with a disease much like scrapie, according to an article appearing this week in Cell. Such a demonstration has, in the past, been called the gold standard of proof for the prion hypothesis, Stanley Prusiner’s Nobel-winning assertion that infectious, self-replicating protein isoforms are the culprit in transmissible spongiform encephalopathies (TSEs) like scrapie, Creutzfeldt-Jakob disease, and mad cow disease. Study coauthor Claudio Soto, said that this demonstration, together with a paper published by Prusiner’s group last summer, should allay most doubts. “There is really little room for skepticism,” he told The Scientist. But the study has done little to quiet prion hypothesis skeptics. “I’m not going to abandon alternative hypotheses for the time being,” said Robert A. Somerville of the Institute for Animal Health, Edinburgh.

While Prusiner’s group had successfully infected a mouse with a recombinant protein derived from bacteria, some argued that their use of transgenic mice susceptible to the disease undercut the power of the demonstration. In the new study, researchers at the University of Texas Medical Branch, Galveston, Universidad Autonoma, Madrid, and the University of Chile in Santiago fine-tuned a cyclical process for amplifying aggregated protein from an infected hamster brain. Through serial dilutions, they were able to infect a wildtype hamster with in vitro–produced aggregates without any traces of the original infectious brain. But skeptics, including a member of Prusiner’s group, argue that using material from a diseased hamster brain could have resulted in residual contamination.

Soto’s group has been using a process that they call protein misfolding cyclic amplification (PMCA), which aids the aggregation of the normal cellular protein PrPc into the misfolded, polymer-forming PrPres that is associated with TSE pathology. The process works in a fashion similar to polymerase chain reaction (PCR) amplification of oligonucleotides. After seeding PrPc with PrPres, the solution is incubated and sonicated. “Once the aggregates become long enough, we split them into smaller pieces so that in a new conversion, a new incubation, they are able to convert more and more of the normal protein,” Soto explained.

Crucially, however, the PrPres “seed” comes from infected hamster brain homogenate, while the normal PrPc comes from healthy hamster brain homogenate. “They actually started from infectious material, and we didn’t,” said Giuseppe Legname, of the University of California, San Francisco, and co-author on the Prusiner paper. “It’s an alternative approach to demonstrate that you might make prions, but to say that these are synthetic prions, it’s very difficult.” Soto insisted that serial dilutions between rounds of PMCA reduce scrapie brain homogenate to an amount equivalent to a 10 to the minus 10th and a 10 to the minus 20th–fold dilution. Infectivity generally drops off after 10 to the minus 9th, according to the paper. “We’ve completely ruled out the possibility that the infectivity is still remaining from… the original brain,” Soto said.

Laura Manuelidis, Yale professor and vociferous critic of the prion hypothesis, pointed to differences in survival between animals inoculated with PMCA-amplified PrPres and control animals inoculated with equivalent amounts of scrapie-derived PrPres. Control animals died from nearly 60 to more than 70 days earlier, indicating, she said, a vast reduction in infectivity for PMCA-derived PrPres. “If PrPres was infectious, you’d expect to make a lot of infectivity… I would argue that it’s 100,000 to 1 million times less infectious than it should be.” In the paper’s results, the authors note a “significant difference” in infectivity for in vitro–generated PrPres, “between 10 and 100 times less infectious.” Somerville said, “I think it’s probably at least on the order of 1000-fold. I think they’ve been quite generous to themselves, there.”

Soto disagreed with these interpretations but noted that his group is “baffled” by the lower infectivity derived from in vitro–produced PrPres. “We think it’s because the distribution of these aggregates is different in our preparation from the in vivo–produced material,” he said. “We may have the same number of protein molecules, but organized in a different number of units.” Alternative explanations include the possibility that they created a different prion strain, Soto said.

Legname noted that similar problems have made it difficult to provide definitive evidence. “I agree the amount of infectivity we created is very little,” he said. “This isn’t because we didn’t create infectivity, but because we don’t know how to create a high level of infectivity.” This is why his group had used transgenic mice producing 16 times the normal amount of normal PrP, he said. The bacterially produced prions they created only worked in sensitive animals. Still, researchers agreed that the PCR-like process Soto’s team has refined may make study easier. “It will be very interesting to see whether these experiments can… work with other TSE strains,” Somerville said. Regardless of the validity of the prion hypothesis, PMCA might aid in diagnostics. “If their work is robust and reproducible, then it should be applied sooner rather than later for the detection of prions in tissue where still it’s very difficult to detect prions, like blood,” said Legname.

E-mail address The Scientist Daily
May 10, 2005

Original web page at BioMed Central

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Fibril shape is the basis of prion strains and cross-species prion infection

New research on prions, the infectious proteins behind “mad cow” disease and Creutzfeld-Jakob disease in humans, suggests that the ability of prions in one species to infect other species depends on the shape of the toxic threadlike fibers produced by the prion. Two studies on the topic appear in the 8 April issue of the journal Cell. Although research suggests that prions from one species rarely infect other species, some scientists believe the species barrier was breached when a new version of Creutzfeld-Jakob disease appeared in humans after several recent epidemics of bovine spongiform encephalopathy or “mad cow” disease. Since then, barriers to the transmission of prion diseases between species “have emerged as a major public health issue,” according to Eric Jones and Witold Surewicz of Case Western Reserve University.

Prion diseases are caused by misfolded variants of the normal prion protein, which aggregate into fibrous tangles called amyloid fibrils and cause fatal wasting of brain tissue. The abnormally folded protein itself appears to act as an infectious agent, transmitting disease without a DNA or RNA genome such as in a virus. Although disease prions seem to infect normal prions by binding to them and forcing them to take on the abnormal configuration, researchers remain uncertain about the exact molecular details of infection.

Earlier studies identified many “strains” of disease prions across mammalian and yeast species. Researchers thought these strains could be defined by differences in the underlying amino acid sequences of the prions. Under this scenario, disease transmission would be more likely between species with similar prion amino acid sequences. But a few mysteries stood in the way: Some individuals harbored several different prion strains that caused different disease outcomes, even though all the prions shared the same amino acid sequence. In some cases, a single amino acid change in one species could completely change its ability to infect a previously “off-limits” species, Surewicz and colleagues found.

In a study published last year in the journal Molecular Cell, Surewuicz and colleagues also demonstrated that a “preseeding” process between animals with different prion amino acid sequences could overcome species barriers. For instance, mouse prion fibrils normally infect humans but not hamsters. But when mouse prions were brought into contact with hamster prion amyloid fibrils, a new strain of mouse fibrils emerged with the ability to infect hamsters but not humans. The new mouse strain had the same amino acid sequence as the original mouse strain but completely different infectious capabilities.

With the help of atomic-level microscopic observation of prions in humans, mice, and hamsters, Jones and Surewicz discovered that it is the specific shape of the amyloid fibrils, and not the amino acid sequences, that may allow prions from one species to infect another. In a second Cell study, Jonathan Weissman and colleagues at the University of California, San Francisco came to the same conclusion in their experiments with yeast. They too discovered that the particular shape of a prion amyloid fibril was the determining factor in whether one species of yeast could infect another yeast species. Just as in the case with the preseeded mice fibrils, a particular fibril shape in Saccharomyces cerevisiae yeast allowed prion transmission to Candida albicans yeast. The transmission event led to a new strain of Candida prion fibrils that could in turn infect Saccharomyces.

Although fibril shape appears to be the deciding infective factor, amino acid sequence is still important because it defines a set of possible preferred fibril shapes that prions can adopt, Weissman says. Species with similar amino acids sequences share an overlapping set of shapes, which helps explain why species with shared sequences have the ability to infect each other. Surewicz says the next step in their research will be to examine fibril shape differences at much higher resolution. Their experiments also used a shortened version of the mammalian prion protein, so they hope to test the fibril factor in a full-length protein soon.

Jones and Surewicz also note that the new findings offer “the unsettling possibility” that repeated cross-species transmission events might eventually create prion fibril strains that can bridge the infection gap between previously separate animals like humans and elk and deer, which suffer from a prion disease called chronic wasting disease. Surewicz stresses, however, prion infection between species is still rare. “Fortunately, transmission by eating is very ineffective. There have been hundreds of thousands of bovine spongiform encephalopathy cases, for example, and lots of people exposed to tainted beef products, but very few cases of variant Creutzfeld-Jakob.” He says there “must be protective mechanisms working there, but we don’t know what they are.”

Source: Cell Press

Bio.com
April 26, 2005

Original web page at Bio.com

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Foot-and-mouth research at risk

Spanish investigators have warned this week that a national law governing research into the foot-and-mouth disease virus could hinder international collaborations on the development of a vaccine against the veterinary pathogen. In a letter made public last Wednesday (March 16), 135 scientists urged the government to reconsider an “incomprehensible” law that they say prevents the country’s leading foot-and-mouth disease research institute from studying the causative agent.

Their protest focuses on a Spanish “royal decree” published in November that aims to enact a 2003 European Commission (EC) directive to tackle foot-and-mouth disease. Scientists were surprised to find that the Madrid-based Center of Animal Health Research (CISA), which has a long tradition on foot-and-mouth disease research, was not listed in the decree as the national center on foot-and-mouth disease.
Instead, the Central Laboratory of Animal Health (LCV) near Madrid was listed as the only reference center authorized to manipulate live foot-and-mouth disease virus for any purpose, including research and fabrication of vaccines.

Scientists in the 20 Spanish research groups working in the field are concerned that their research cannot continue. “CISA is the only center with the right biosafety level and with active research lines on foot-and-mouth disease virus,” CISA researcher Juan Bárcena told The Scientist. “This is a serious political mistake,” said CISA director Esteban Domingo, noting that politics is behind the decision to leave the center off the list. “An influential group at the Farming Ministry is trying to retake control over CISA,” he said. The center, launched in 1993, belonged to the Farming Ministry until 2000. Since then, it has been attached to the Science Ministry.
According to Bárcena, “Some people at the Farming Ministry want a shift in the type of research currently performed in CISA.” “It’s said that we are too involved in basic research and that we need to engage in applied lines such a clinical trials with the aim of getting short-term results,” Bárcena said.

A total of 16 scientists are involved in foot-and-mouth disease virus research in CISA, with seven projects underway. “Four of these projects are European projects performed in collaboration with research centers at Belgium, United Kingdom, Italy, The Netherlands, Germany, France, and Switzerland,” said Bárcena. There is a “risk that all of these will become paralyzed as a result of the royal decree,” he said.These European projects, Bárcena said, are mainly devoted to designing new vaccines, including DNA-based vaccines, against the virus. “Spanish research on foot-and-mouth disease virus is pioneering at a worldwide level,” the open letter says. “It ranks third in the list of research papers, after the UK and USA.”

CISA scientists say they were not consulted by the government about its decision not to include CISA in the Spanish decree. They also say that the EU directive allows for more than one center to be listed as reference labs, as is the case in Germany. “It would be more logical to have two reference centers in Spain,” said Francisco Sobrino, a scientist at CISA and at Madrid’s Molecular Biology Centre. Concha Gómez-Tejedor, LCV director, told The Scientist that she has offered her center to CISA researchers to continue their research. “What I won’t tolerate is that my center is criticized as a way for CISA researchers to resolve their problems,” she said.

But Sobrino notes that although LCV has a right biosafety level, its facilities are not prepared to be used for foot-and-mouth disease virus research. “Their animal facility is too small compared to CISA’s,” he said, adding that “there is no research tradition in LCV.” María Echevarría, head of the Farming General Direction, told The Scientist that although LCV is the sole reference center, CISA scientists “can continue their research on foot-and-mouth disease virus.” But Bárcena said that he “distrusts her comments” and that “with the royal decree in hand, if we continue doing [such] research, we may be penalized.”

Yet the decree does not mention how researchers found conducting foot-and-mouth virus research in centers other than LCV would be penalized. Eva Quintanilla, a spokeswoman for the Spanish Science Ministry, said, “Our will is that CISA scientists continue their research on foot-and-mouth disease virus, and we are working together with the Farming Ministry to do so.”

BioMed Central
April 12, 2005

Original web page at BioMed Central