Prion Disease: January 2000 News
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France to introduce mad cow disease tests in February
Prion inactivation: what works?
Blood infectivity issues reviewed
Algeria rejects German cows over bovine herpes virus
Rachel #683: Mad Cow Disease And Humans
Student dissertation on prion disease
Mystery of blood-brain barrier unlocked
Beef-on-bone to be sold again

France to screen cattle for mad cow disease

23 Jan 00 Associated Press
Opinion (webmaster): This is . Never before has a slaughterhouse-based random testing program for BSE been implemented on this scale. This is a major milestone in the history of BSE but also a major provocation whose fallout is difficult to foresee. Low-cost validated tests have been available for a while, but not very many countries wanted to know the extent of infection in their herds. Britain in particular has never performed any such testing over the last 15 years nor allowed importing partners nor scientists access to slaughterhouse lines. BSE may be entrenched already in Britain as an endemic infection, just as scrapie is.

One wonders if other countries such as Holland, Belgium, Germany, and the US will be inspired (or pressured) by the French example. Random sampling is not likely to find bovine prion disease in countries where it is rare, but it is not such a giant step from there to testing of all slaughtered animals.

France did not provide details of the testing method to be deployed (the most sensitive method,immunohistochemistry?) nor make clear if or when testing results would be released (monthly on the internet?). If trace-back to the source herd is still possible, France probably would continue its current policy of herd destruction.

Many question arises such as decontamination of equipment after discovery of positive cases, what to do about infected cows outside the random sampling system that still go to into the human food chain, and what to do with new quantitative knowledge of how many infected cows have already been eaten over the last 5 years.

Are the cows selected for testing set aside until the test results are available (meaning that positive cases can be incinerated) or is the brain sample taken and the carcass allowed to procede through the processing line? It makes no big difference from a statistical point of view since untested infected cows have been getting through for some time, but the latter method will make beef consumption a game of Russian roulette to the public.

Comment (Pr Jeanne Brugere-Picoux to ProMed 31 Jan 00):

The test will be the French test commercialized by Biorad (ELISA test). A first pilot study will be done on 40 000 cows at risk (emergency slaughter and found dead). [This is not a random selection as announced -- webmaster] In the next months it will be very interesting to compare this French test in the field with "prionics" test (the evaluation of the European Commission) and demonstrate the very good sensibility of French test (x30 by comparison with "prionics").

It will be sure that we will find more cases of BSE (like in Switzerland). If French experimentation confirm the demonstration of the experience of Switzerland, it will be very important to ask for an official application of the test in all European countries with or without BSE sporadic cases.

We know the difficulty of the antemortem diagnosis of this disease : only clinical and with changes of behavior only seen by the owner and not recognized at the slaughterhouse with this early changes. And we cannot exclude - a reluctance of some owners to declare a suspicion (English estimation was 1 out of 2 cases) - that some cases can be atypicals and difficult to be recognized at the clinical examination (cases of emergency slaughters, downers cows...)"

Comment (Vincent Dedet: The EC report on the Internet. explains that the three tests : Enfer (Ireland), Prionics (CH) and CEA (FR) are 100% sensitive and specific based on the results of 1400 brains treated blindly by the labs and prepared by the Commission's lab. Then 200 samples of + brain were diluted in - brain. And the French test was then 10 times more powerful than Enfer and 30 times more powerful than Prionics.

It is hard data. Of course, the labs have been iddle since last June, when these tests were performed. The French lab (CEA) has reduced the time needed for its test and is able to perform it routinely in less than 6 h.

The French government plans to begin screening the country's cattle herds for mad cow disease as of February, Health Secretary Dominique Gillot said Sunday. "We'll test animals arriving at slaughter houses," Gillot said in an interview with France Inter radio. "That will give us an indication of how widespread the epidemic has become among our herds."

Gillot said the tests would involve taking brain and bone samples of the cows destined for human consumption, and that "tens of thousands" of cattle would be tested. She said France had called on its European Union partners, especially Britain, to adopt similar practices.

In 1999, there were 28 cases of mad cow disease in France. In January, the first case of the year was detected in the northwestern Finistere region. Authorities say they expect new cases in France until 2001, five years after stringent prevention measures were taken to prevent outbreaks. The disease has an average incubation period of five years.

France has provoked a diplomatic spat by keeping in place a ban on beef from Britain, where mad cow disease -- or bovine spongiform encephalopathy -- originated in 1996. In August, the European Union declared that beef from Britain was again safe for import, but France angered its cross-channel neighbor by continuing its ban. The executive arm of the European Union has started a legal case against France at the European Court of Justice.

France to introduce mad cow disease tests in February

Dow Jones Sun, Jan 23, 2000
The French government will introduce in February the first national testing campaign to screen French cattle for mad cow disease, or BSE, health secretary Dominique Gillot said in an interview Sunday with newspaper Le Journal du Dimanche.

In the interview, the minister confirmed that the screening tests are ready, but final decisions have yet to be made concerning the organization of the testing, including safety conditions for people performing the tests.

Speaking on radio station France-Inter, the minister said brain and marrow samples will be taken from cows destined for human consumption as they arrive at slaughter houses. The results will be used to try to detect signs of BSE before they are physically visible in the animals in order to gauge the extent of infection in France's total cattle population, said the minister.

He also said France has asked all members of the European Union, including Britain, to carry out similar testing in order to identify the means of transmission of BSE across Europe's cattle population.

France to Screen Herds for Mad Cow Disease

Sunday January 23, 2000 Reuters
France said on Sunday it would set up a screening program in the next few weeks to check that cattle ready for slaughter were not infected with mad cow disease. Health Minister Dominique Gillot said cattle with no outward signs of the disease would have their brains and marrow tested to ensure infected cows did not reach abattoirs.

``These tests permit us to know more about the reality of the risks,'' Gillot told Sunday newspaper Journal du Dimanche in an interview. ``On their own, they are not enough to guarantee security,'' she was quoted as saying.

The European Commission took France to court earlier this month for refusing to lift its blockade on British beef over mad cow disease fears. The EU lifted the ban in August. The EU-wide ban was put in place in 1996 after a serious outbreak of the disease among British herds, but EU scientists have said the meat is now safe to export under a regime of checks.

French health officials said earlier in January that the screening would be carried out on a sample of cows to find incubating cases of bovine spongiform encephalopathy (BSE), or mad cow disease. France reported a fresh case of the mad cow disease on January 17, the first discovered this year. France registered 31 cases of the disease in 1999.

The EU ban on British beef was imposed after the British government admitted a possible link between mad cow disease and a form of the human disorder Creutzfeld-Jakob Disease (nvCJD) which has so far killed at least 62 people.

Ministry Reports Another Case In Western France

1/24/2000 By: Julien Ponthus, Bridge News
The French agriculture ministry announced a new case of mad cow disease in western France Monday. The cow was born in 1995 and was destroyed this weekend along with its herd of 91 cows, the ministry said.

So far, 4 cases have been reported in 2000. The ministry indicated, as usual in these cases, that food contamination previous to 1996 is the explanation it favors. After that date, the ministry claims that effective measures disabling food infection were taken. Because the incubation period of the disease is 5 years, France claims that the disease should no longer appear after 2001. Frances bovine livestock consists of 21 million cows.

Coroners 'concealed' BSE deaths

UK/Telegraph/Tues. Jan. 25, 2000 By David Brown, Agriculture Editor
THE number of victims of the human form of bovine spongiform encephalopathy could be higher than official figures suggest because coroners refused full inquests on some of them, it was claimed yesterday.

A campaign group, Inquest, said that a number of families had been denied inquests on victims of the new variant Creutzfeldt-Jakob disease (nvCJD) which has been linked to BSE in cattle, after coroners decided that the deaths were due to "natural causes". [This practise is also very extensive in the US -- see 1, 2, 3. The job of coronor, historically medical and accountability-oriented, has become highly politicized, focusing now more on protecting industry and officialdom from legal claims. -- webmaster]

So far 49 people in Britain have died from vCJD according to Government figures but the group, which is demanding tougher ministerial guidelines for coroners, said it was possible that some cases had "slipped through the net". Figures which are expected to show an increase in the number of victims will be issued next month.

Rachel #683: Mad Cow Disease And Humans

January 20, 2000 Rachel's Environment & Health Weekly #683    
When a new form of an old human disease appeared in England in 1995, some medical specialists immediately suspected that it might be a human version of "mad cow disease," but they had no proof.[1] Mad cow disease had appeared in British dairy cattle for the first time in 1985 and during the subsequent decade 175,000 British cows had died from it. British health authorities spent that decade reassuring the public that there was no danger >from eating the meat of infected cows. They said a "species barrier" prevented mad cows from infecting humans. A "species barrier" does prevent many diseases from crossing from one species to another -- for example, measles and canine distemper are closely related diseases, but dogs don't get measles and humans don't get distemper.

While the British government was placing its faith in the species barrier, British citizens began to die of a new disease, called "new variant Creutzfeld-Jakob disease" or nvCJD. A similar disease, CJD (Creutzfeld-Jakob disease) had been recognized for a long time but it almost never occurs in people younger than 30; nvCJD, on the other hand, strikes people as young as 13. There are several other differences between CJD and nvCJD, so nvCJD represents something new. To date, nvCJD has killed 48 people in England and one or two others elsewhere in Europe. The main feature of both mad cow disease and nvCJD is the progressive destruction of brain cells, inevitably leading to total disability and death.

New research published late in 1999 showed that nvCJD is, in fact, a human form of mad cow disease,[2] dashing all hope that a species barrier can protect humans from this deadly bovine affliction.

Mad cow disease is formally known as "bovine spongiform encephalopathy" or BSE. BSE is the cow version of a larger class of diseases called "transmissible spongiform encephalopathies," or TSEs. TSEs can afflict sheep, deer, elk, cows, mink, cats, squirrels, monkeys, humans and other species. In all species the symptoms of TSEs are the same -- progressive destruction of brain cells leading to dementia and death.

Traditional Creutzfeld-Jakob disease (CJD) is a rare human affliction. The visible symptoms are similar to Alzheimer's disease; in fact, CJD is sometimes diagnosed as Alzheimer's and therefore may go unrecognized. CJD strikes one in a million people almost all of whom are older than 55. In people younger than age 30, CJD is extremely rare, striking an average of 5 people per billion each year, worldwide (not counting the recent outbreak in England).

In cows, the latency (or incubation) period for mad cow disease is about 5 years, meaning that cows have the disease for five years before symptoms begin to appear. No one knows the latency period for nvCJD in humans, but it is thought to be around 10 years. Because of this uncertainty, no one is sure how many people in England already have the disease but are not yet showing symptoms. The British government's chief medical officer, Professor Liam Donaldson, said December 21, 1999, "We're not going to know for several years whether the size of the epidemic will be a small one, in other words in the hundreds, or a very large one, in the hundreds of thousands."

The epidemic of mad cow disease was caused by an agricultural innovation -- feeding dead cows to live cows. Cows are, by nature, vegetarians. But modern agricultural techniques changed that. Cows that died mysteriously were sent to rendering plants where they were boiled down and ground up into the consistency of brown sugar, and eventually added to cattle feed. It was later determined that mad cow disease was being transmitted through such feed, and especially through certain specific tissues -- brain, spinal cord, eyes, spleen and perhaps other nerve tissues.

Ten new cases of nvCJD were reported in England in 1999, bringing the total to 48. It has been more than 10 years since government authorities banned the use of the particular parts of cows thought to transmit mad cow disease. The appearance of new cases of nvCJD in 1999 implies either that the latency period for the disease is longer than 10 years, or that infected meat was not effectively eliminated from the food chain when government authorities said it was, or both.

The SUNDAY TIMES of London reported in late December that some meat banned for human consumption is still being marketed in England. After the mad cow scandal erupted, the British government attempted to eradicate the disease by requiring that all cows older than 30 months be slaughtered. As a result, by last September more than 2.5 million British cows had been killed. But the TIMES reported that British investigators have documented at least 50 cases of farmers and cattle dealers using bogus identity documents to falsify the ages of cows in order to sell them for human consumption. Furthermore, the Agriculture Ministry acknowledged that as many as 90,000 cattle could not be accounted for. About 1600 new cases of mad cow disease are still being reported each year in England.

In December, French health authorities announced finding a second case of nvCJD, a 36-year-old woman in Paris. France has continued to refuse to import British beef, even though the European Union on August 1, 1999, formally declared British beef as safe as any in the European Union. The European Union said in December it will take France to the European Court of Justice to force it to import British beef. Germany is also refusing to import British beef.

The U.S. government says mad cow disease has never been observed in any U.S. cows. However, a closely-related TSE disease, called chronic wasting disease (CWD), has been increasing for almost 20 years among wild deer and elk in northern Colorado and southern Wyoming. Since 1981, CWD has been spreading slowly among wild deer and elk herds in the Rocky Mountains and now afflicts between 4% and 8% of 62,000 deer in the region between Fort Collins, Colorado and Cheyenne, Wyoming.

During 1999, CWD erupted among a herd of elk on the David Kesler Game Farm near Philipsburg, Montana, which raised elk commercially. A few of Mr. Kesler's elk had been shipped to Oklahoma and Idaho, and perhaps elsewhere, and CWD was discovered in some of those animals, too. In early December, Montana health authorities slaughtered 81 elk on Mr. Kesler's farm. They initially announced plans to incinerate the carcasses, but later decided that incineration would be too expensive.

The animals were finally buried at the High Plains Sanitary Landfill north of Great Falls. Equipment used to feed, water and care for the animals was also buried in the landfill. Montana authorities announced that the fenceline at the elk farm would be decontaminated, but they did not say what procedure they would use. Nor did they announce what would become of Mr. Kesler's contaminated land. The disease agent that causes CWD -- a prion protein -- is very hardy and resists destruction by traditional sterilization techniques like alcohol and heat.

The diseased elk carcasses in the High Plains landfill have been buried under a mound of garbage but will still be accessible to rainwater and perhaps to scavenging animals.

[Journalist Hal Herring writes from Corvallis, MT: " The elk destroyed at the Kesler ranch near Philipsburg, Montana WERE NOT shipped to the Great Falls, MT landfill in the end. Public opinion prevailed. They were incinerated, in an air curtain incinerator imported from Mandan, N.Dak., and fueled by 145 cords of firewood.

The ashes were buried onsite at the Kesler ranch. Also Kesler elk shipped to Oklahoma, to Hardin, Mt and perhaps elsewhere have developed CWD. A story that I wrote about the Kesler place is in the next issue of High Country News. There is some other info on Kesler and the shipping in a Sept. High country News article that I wrote--an article more closely confined to CWD"]

In northeastern Colorado and southeastern Wyoming, state officials are urging hunters to protect themselves when dressing wild deer and elk they have shot. Hunters should wear rubber gloves, minimize contact with brain and spinal cord tissues, discard the brain, spinal cord, eyes, spleen and lymph nodes and definitely not eat them. There is no evidence that CWD can cross over from deer and elk to humans, but there was no firm evidence that mad cow disease could afflict humans until 1999, so wildlife officials in the Rocky Mountain states say caution is warranted.

Writing in the BOSTON GLOBE, Terry J. Allen reported in late 1999 that, since 1996, Creutzfeld-Jakob disease has been identified in 3 Americans younger than age 30.[3] All three are known to have hunted extensively or eaten venison. There is no evidence that CWD disease has jumped from deer or elk to humans, but the appearance of this extremely-rare disease in young people was the first evidence of a problem in England, so health authorities in the U.S. say they are aggressively investigating all the possibilities.

A statistician at the federal Centers for Disease Control (CDC) in Atlanta told Terry Allen that, if one more case of CJD had surfaced in a person younger than 30 in the U.S., it "might tip the balance," meaning it might convince authorities that something truly unusual was occurring. Dr. Michael Hansen of Consumer's Union says, "Given how rare the disease is in young people and how difficult it is to make a diagnosis, the possibility that some cases go undetected cannot be ruled out."[3]

Indeed, of the 3 cases detected in the U.S. since 1996, one nearly went undetected. Last year in Utah, Doug McEwan, 28, began to show an array of mysterious symptoms: loss of memory, loss of motor control, mood swings, and disorientation. His wife, Tracey, says his doctors conducted hundreds of tests but could not diagnose his disease. She happened to see a TV program on mad cow disease and she insisted that Doug's doctors must test for CJD. A brain biopsy confirmed the diagnosis.

One of the three young CJD victims had eaten deer shot near Rangely, Maine, so last November federal officials took samples of brains from 299 deer shot in western Maine. Authorities said at the time they were quite sure Maine deer are not harboring CWD. So far, test results have not been released.

Federal authorities have quarantined two herds of sheep in Vermont because they say the sheep may have been given feed that contained parts of animals afflicted by mad cow disease. The sheep had been imported into Vermont from Belgium and the Netherlands, where they may have been fed improperly. A similar herd of sheep in New York state was recently purchased by the federal government and slaughtered.[4]

Meanwhile, a 68-year-old Indiana man with a fondness for beef-brain sandwiches died of CJD last summer. Beef-brain sandwiches are a local delicacy in Indiana, introduced years ago by German immigrants. The EVANSVILLE (INDIANA) COURIER reported that John Hiedingsfelder, a forensic pathologist in Evansville, said he had seen three cases of CJD in the past year. No connection to mad cow disease has been established in the Indiana cases. Roberta Heiman, a staff writer for the EVANSVILLE (INDIANA) COURIER reportedly received a warning from a cattleman's association not to publish any further articles about this subject.

 
[1] Unless a specific source is cited, information in this issue
of Rachel's was taken from www.mad-cow.org Sources of information are cited there.

[2] Michael R. Scott and others, "Compelling transgenic evidence
for transmission of bovine spongiform encephalopathy prions in
humans," PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES Vol. 96,
No. 26 (December 21, 1999), pgs. 15137-15142.

[3] Terry J. Allen, "Rare, Animal-Borne Disease a Medical
Mystery; Officials Examine Maine Deer in Hunt for Clues," BOSTON
GLOBE December 12, 1999, pg. C26.

[4] Matthew Taylor, "Mad Cow Fears, Anger on Farms; Two Imported
Sheep Herds Quarantined in Vermont," BOSTON GLOBE October 31,
1999, pg. F24.

Algeria rejects German cows

1/14/2000 North Africa Journal
Between September and November 1999, Algeria's official veterinarian services have killed 131 cows believed to be carrying the Bovine Spongiform Encephalopathy known as BSE or mad-cow disease. [These cows had bovine herpes, not BSE: see below -- webmaster]

The cattle were imported by private operators and German authorities have been informed by the problem. As a result, Algeria has suspended all imports of German beef until further notice.

Following the Algerian decision, Germany sent two envoys to Algeria to investigate the manner. They are Dr. Werner Zwingmann, head of the federal veterinary services and Dr. Klaus Meyn, representing the German beef and dairy industries.

Their investigation within Algeria led to the recognition that the results of the Algerian authorities were correct and they pledged to reimburse the importers and cattle owners some form of compensation.

Comment (Dr. Klaus Meyn, German Cattle Breeders' Federation (ADR)): "The disease under consideration is not BSE, but the disease Bovine Herpes Virus no. 1 (BHV1), also called Infectious Bovine Rhinotracheitis (IBR). No case of BSE in cattle born in Germany has occurred so far. Furthermore, the cattle in question were German pedigree dairy heifers for breeding and no imports of beef.

We have acknowledged in principle that the quarantine measures have not been sufficient and that some form of compensation would be justified, but no amounts have, so far, been communicated to us."

Comment (Dr. Wolfgang Klee, Medical Animal Clinic, University of Munich): " Algeria has indeed stopped import of German dairy cattle (not beef) from Germany. The cattle had IBR, an infection caused by BHV1 (bovine herpesvirus 1), which cannot be transmitted to humans.

Comment (webmaster): This incident is similar to the rabies outbreak in Ecuador last year which was also initially represented as BSE by the press. However, caution is appropriate in regards to both bovine herpesvirus and bovine AIDS due to latency. Were not the same things were said about scrapie and BSE, that they could not transmit to humans? Medline carries these articles:

Activation of bovine immunodeficiency-like virus expression by bovine herpesvirus type 1.

Geng Y, et al. 
Virology. 1992 Apr;187(2):832-

Transport of viruses through fetal membranes: an in vitro model of perinatal transmission.

J Med Virol 1998 Apr;54(4):313-
Rokos K, Wang H, Seeger J, Schafer A, Paul

The latency-related gene of bovine herpesvirus 1 inhibits programmed cell death.

J Virol. 1999 Dec;73(12):9734-40.
Ciacci-Zanella J, et al.

Serologic survey of white-tailed deer on Anticosti Island, Quebec for bovine herpesvirus 1, bovine viral diarrhea, and parainfluenza 3.

J Wildl Dis 1991 Oct;27(4):569-7
Sadi L, Joyal R, St-Georges M, Lamontagne L a.

Replication of bovine herpesvirus type 4 in human cells in vitro.

J Clin Microbiol 1998 Jul;36(7):2109-11
Egyed L
"Herpesviruses are widespread viruses, causing severe infections in both humans and animals. Eradication of herpesviruses is extremely difficult because of their ability to establish latent and life-long infections. However, latency is only one tool that has evolved in herpesviruses to successfully infect their hosts; such viruses display a wide (and still incompletely known) panoply of genes and proteins that are able to counteract immune responses of their hosts....

Animal herpesviruses, because of their striking similarity to human ones, are suitable models to study the molecular biology of herpesviruses and develop strategies aimed at designing neurotropic live vectors for gene therapy as well as engineered attenuated vaccines.

BHV-1 is a neurotropic herpesvirus causing infectious rhinotracheitis (IBR) in cattle. It is a major plague in zootechnics and commercial trade, because of its ability to spread through asymptomatic carrier animals, frozen semen, and embryos. Such portals of infections are also important for human herpesviruses, which mainly cause systemic, eye, and genital tract infections, leading even to the development of cancer.

Inactivation of transmissible degenerative encephalopathy agents: a review.

Taylor DM
Vet J 2000 Jan;159(1):10-17
Neuropathogenesis Unit, Institute for Animal Health,   Edinburgh, UK
The unconventional agents that cause transmissible degenerative encephalopathies, such as bovine spongiform encephalopathy, scrapie, and Creutzfeldt-Jakob disease (CJD), are relatively resistant to inactivation by standard decontamination procedures.

The only methods that appear to be completely effective under worst-case conditions are strong sodium hypochlorite solutions [bleach] or hot solutions of sodium hydroxide.

Other procedures that result in significant degrees of inactivation are described. The infectivity levels in histologically-fixed tissue can be reduced substantially by treatment with concentrated formic acid without adversely affecting the microscopic quality of the tissue.

Inactivation of prions by physical and chemical means.

J Hosp Infect 1999 Dec;43 Suppl:S69-76
Taylor DM
 Neuropathogenesis Unit, Institute for Animal Health, Edinburgh, UK. 
Prions are very resistant to inactivation, and accidental transmission has occurred through the use of inadequate decontamination procedures. Strong sodium hypochiorite solutions achieve inactivation but other chlorine-releasing compounds are less effective. 2M sodium hydroxide leads to substantial but incomplete inactivation; other chemical procedures such as the use of proprietary phenolic disinfectants are much less less effective. Infectivity can survive autoclaving at 132-138 degrees C, and under certain conditions the effectiveness of autoclaving actually declines as the temperature is increased.

The small resistant subpopulations that survive autoclaving are not inactivated by simply re-autoclaving, and they acquire biological characteristics that differentiate them from the main population. Despite the limitations of autoclaving, combining autoclaving (even at 121 degrees C) with a sodium hydroxide treatment is extremely effective. Protein-fixation (e.g., by ethanol or formalin) substantially enhances the thermostability of these agents. This suggests that future successful inactivation strategies might best be developed by studying procedures that avoid protein-fixation.

Opinion (webmaster): Many members of the public under the impression that prions are indestructable. Indeed, they are quite resistant to methods conventionally effective with viruses and bacteria, such as cooking or steam sterilization (hospital autoclaving). The chemicals described above are common industrial solvents, one a strong non-specific oxidant and the other creating very alkaline pH. While effective according to the article, they would have no utility in food grade items and little applicability to high-tech hospital surgical instruments.

Prion diseases, blood and the immune system: concerns and reality

Haematologica 2000 Jan;85(1):3-10 free pdf 
Aguzzi A and about 50 co-authors
There is a great amount of uncertainty about the nature of the agent which causes spongiform encephalopathies. In recent years the occurrence of bovine spongiform encephalopathy and of new variant-Creutzfeldt Jakob disease, has raised concerns that prions may, under certain circumstances, contaminate the blood supply. This review article illustrates the problems with which research in this field is fraught, and presents some of the arguments which are controversially discussed in the field.... Opinion (webmaster): Up to now, almost all articles on prion infectivity have been authored by American groups affiliated with the blood industry. However, Europe is probably more at risk to contaminated donations by individuals with subclinical but progressing nvCJD infections. Author Aguzzi has published extensive research on the role of the immune system in prion infections.

Monitoring plasma processing steps with a sensitive Western blot assay for the detection of the prion protein.

J Virol Methods 2000 Jan;84(1):77-89 
Lee DC, Stenland CJ, Hartwell RC, Ford EK, Cai K, Miller JL, Gilligan KJ, Rubenstein R, Fournel M, Petteway SR Jr
Department of Pathogen Safety Research/Biological Products, Bayer Corp., Research Triangle Park, NC 27709, USA
. Determining the risk of transmissible spongiform encephalopathy (TSE) transmission by blood or plasma-derived products requires sensitive and specific assays for the detection of either infectivity or a reliable marker for infectivity.

To this end, a Western blot assay that is both sensitive and reproducible for the detection of PrP(RES), a marker for TSE infectivity, was developed. Using the 263K strain of TSE as a model system, the Western blot assay proved to be sensitive, specific and quantitative over a 3-4 log dynamic range.

Compared to the rodent bioassay, the assay was shown to detect PrP(RES) down to approximately 10(3.4) IU/ml which is approximately 5-10 pg of PrP or approximately 10-20 ng brain equivalents. The Western blot was applied to monitor the partitioning of spiked PrP(Sc) through three plasma fractionation steps, cryoprecipitation, fraction I and fraction III, that are common to the purification of several human plasma-derived therapeutic products including albumin and immunoglobulins.

The results from these studies demonstrated 1 log, 1 log and 4 logs of PrP(Sc) partitioning away from the effluent fraction for the cryoprecipitation, fraction I and fraction III steps, respectively.

Opinion (webmaster): This abstract appeared on Medline on 24 Jsn 00. It gives some idea what researchers at the pharmaceutical firm Bayer have been up to as far as developing prion assays for blood product safety. It is clear that the 3 steps of purification are having their effect but whether they think the amount left at the end is significant over a human lifespan if injected in childhood is not made clear by the abstract. Lab mice are unsatisfactory in that the lifespan is just two years.

Student dissertation on prion disease

Robert J. Elbourn Queen Mary & Westfield College
Recent graduate from Imperial College London, degree in Biology with Microbiology
Opinion (webmaster): This web dissertation is a very extensive analysis and summary of many issues that come up in prions and prion disease. It may be of interest to visitors needing an overview and background in a single article

Mystery of blood-brain barrier unlocked

Friday January 7  2000 Reuters Health.   SOURCE: Journal of Neurochemistry 2000;74
By Merritt McKinney
Opinion (webmaster): No therapy for CJD is in sight at this time, but compounds that have promise in vitro would need to get past the blood-brain barrier, a problem in many other neurological diseases as well. Thus, this development could help in the eventual treatment of CJD.

Scientists have identified the receptor in the brain that regulates the blood-brain barrier, a group of cells that controls which substances enter the brain. The discovery may lead to the development of drugs that can cross the blood-brain barrier as well as a better understanding of diseases like multiple sclerosis and Alzheimer's disease, the study's lead author told Reuters Health in an interview.

Scientists have known about the blood-brain barrier for more than 100 years, but how it works has been a mystery for the most part, according to Dr. Alessio Fasano, of the University of Maryland School of Medicine in Baltimore.

``Everyone knew about the existence of the gate, but no one knew how to open it,'' Fasano said.

Earlier research has shown that two proteins, zonulin and zot, are involved in the absorption of substances in the intestine. When these proteins bond with receptors in the intestine, substances are able to pass between the cells that make up the intestinal wall. In the new research, Fasano and his colleagues have discovered that these proteins play a similar role in the blood-brain barrier when they attach to a certain brain receptor.

In his comments to Reuters Health, Fasano said that the discovery may lead to the development of drugs that would trigger the blood-brain barrier to open up long enough for medication to reach the brain. This approach would be especially helpful for people with brain cancer who need to have medicine delivered directly to the brain.

Fasano also noted that studying how the blood-brain barrier normally works may lead to a better understanding of what happens in illnesses like multiple sclerosis, Alzheimer's disease, and certain HIV-related brain infections. All of these diseases involve a faulty blood-brain barrier, which remains open when it should be closed, he said. .

Tories demand answers after beef-on-bone denial

Thu, Jan 20, 2000 By Jamie Lyons and Karen Edwards, PA News
The Conservatives were today demanding answers over a claim that the beef-on-the-bone ban could soon be reintroduced.

Shadow agriculture minister Tim Yeo is unconvinced by a Ministry of Agriculture, Fisheries and Food denial of the claim contained in an internal Welsh Assembly document, inadvertently sent to journalists. It said the ban could be reintroduced because of new EU regulations due to come into force on July 1.

"Even with the denial it has been disastrous for British farming," he said. "I will be tabling questions in the House of Commons at the first possible opportunity looking for full and frank answers as to why and how this occurred."

A MAFF spokesman said the document was a private memo written by a junior official who had wrongly assessed the information. It was "not intended for dissemination even within the civil service", he said. "There is not going to be a ban, that's not true. The official's assessment of what the European Commission is looking at is incorrect. "This document that was e-mailed out by mistake by somebody in Cardiff is not an official document. I have checked with senior colleagues who were at the meeting and they confirmed that the assessment contained in this e-mail is not correct either in tone or content. "It does not accurately reflect what was discussed."

The Welsh Assembly document said efforts were being made to get the European Community to reverse its decision as the effects were "very serious". Beef-on-the-bone was banned in December 1997 because of fears over new variant CJD, suspected of being the human form of mad cow disease.

Agriculture Minister Nick Brown finally lifted the ban on December 17 last year. Instantly, supermarkets reported soaring sales as consumers queued up to buy cuts such as T-bone steaks. Throughout the two years of the ban, it was controversial. Mr Brown himself said he wanted to lift it.

The Prince of Wales flouted the ban and ate beef cut from the bone in front of the cameras, and many butchers blatantly ignored the restrictions and kept the meat on their shelves.

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