Spontaneous generation of mammalian prions
Julie A. Edgeworth, Nathalie Gros, Jack Alden, Susan Joiner, Jonathan D. F. Wadsworth, Jackie Linehan, Sebastian Brandner, Graham S. Jackson, Charles Weissmann1,2, and John Collinge1 + Author Affiliations
Medical Research Council Prion Unit, Department of Neurodegenerative Disease, University College London Institute of Neurology, London WC1N 3BG, United Kingdom ? 2Present address: Department of Infectology, Scripps Florida, Jupiter, FL 33458.
Edited by David S. Eisenberg, University of California, Los Angeles, CA, and approved June 29, 2010 (received for review March 28, 2010)
Abstract Prions are transmissible agents that cause lethal neurodegeneration in humans and other mammals. Prions bind avidly to metal surfaces such as steel wires and, when surface-bound, can initiate infection of brain or cultured cells with remarkable efficiency. While investigating the properties of metal-bound prions by using the scrapie cell assay to measure infectivity, we observed, at low frequency, positive assay results in control groups in which metal wires had been coated with uninfected mouse brain homogenate. This phenomenon proved to be reproducible in rigorous and exhaustive control experiments designed to exclude prion contamination. The infectivity generated in cell culture could be readily transferred to mice and had strain characteristics distinct from the mouse-adapted prion strains used in the laboratory. The apparent "spontaneous generation" of prions from normal brain tissue could result if the metal surface, possibly with bound cofactors, catalyzed de novo formation of prions from normal cellular prion protein. Alternatively, if prions were naturally present in the brain at levels not detectable by conventional methods, metal surfaces might concentrate them to the extent that they become quantifiable by the scrapie cell assay.
snip...
Discussion Human prion diseases may be acquired, inherited (with pathogenic germline mutation in PRNP) or sporadic, probably as a consequence of rare, stochastic de novo formation of prions (25).
Deleault et al. (8) reported de novo generation of prions by the protein misfolding cyclic amplification (PMCA) procedure, using PrPC purified from normal brain as substrate. However, the resulting strain could not be distinguished from RML. Generation of novel prion strains by PMCA was also reported by Barria et al. (26) and by Wang et al. in a novel PMCA system based on purified recombinant PrP, a synthetic anionic lipid and liver RNA (10).
Prion strains, even those subjected to biological cloning, may be heterogeneous at a molecular level and consist of an ensemble or quasispecies which may be selected by, and adapt in, different hosts (23, 24). According to such a model, this novel strain may have been selected from an ensemble of spontaneous prions as the preferred molecular species for stable propagation in PK1 cells, essentially adapting to PK1 cells in a similar way in which RML prions appear to have done.
PrPSc could occur at very low levels in healthy brains, almost never reaching levels that lead to disease (27). If so, "uninfected" brain homogenates might contain undetected PrPSc seeds that are concentrated on steel wires (16) and infect PK1 cells in our experiments. However, if normal brain is devoid of prions, our results mean that infectivity is generated de novo, perhaps by a mechanism in which seed formation is catalyzed by the steel surface (Fig. S1). It is also possible that brain lipids and/or RNA, known to be able to act as cofactors in some experimental systems (8, 10), could have bound to wires and played a role in triggering de novo prion formation in PK1 cells.
This raises the question as to whether "spontaneous prions" are indeed generated de novo or whether brains from uninfected animals contain a low level of prions that are concentrated by adsorption to the wire surface and thereby rendered detectable by the SCA. Differentiating between these possibilities is a challenging one but could be achieved by kinetic experiments: propagation of preexistent seed should be proportional to brain homogenate concentration; de novo seed formation would be a higher-order function of concentration (28, 29).
http://www.pnas.org/content/early/2010/07/16/1004036107.abstract?etoc
This article contains supporting information online at
http://www.pnas.org/content/suppl/2010/07/18/1004036107.DCSupplemental
FULL TEXT PDF ;
http://www.pnas.org/content/early/2010/07/16/1004036107.full.pdf+html
Greetings,
SO, problem solved ? Are we all suppose to believe that the atypical BSE strains and sporadic CJD strains, are just another happenstance of spontaneous mutation in all cases, just an old cow disease such as sporadic CJD in humans i.e. old people disease, another spontaneous mutation in all cases of sporadic CJD. SO, we are suppose to believe that out of all these atypical BSE cases popping up around the globe, NONE were caused by feed ? I don't believe that for a New York minute. I don't believe all cases of sporadic CJD are all spontaneous either. Either the UKBSEnvCJD theory was totally wrong, or this BSe that all other TSE are of a spontaneous mutation is wrong. You cannot have your cake, and eat it too.
With headlines like, Contact with steel 'linked to CJD' , or Infectious prions can suddenly erupt from normal brain tissue , or infectious prions can arise spontaneously in normal brain tissue , I decided to wait and look at the study. glad I did. nothing about this study shows that 85% to 90% of all human TSE i.e. the sporadic CJD's show they are a spontaneous generation from nothing. It does however cause confusion, of which, in my opinion, could have been resolved. I will ask the same question here, I ask Professor Stanley Prusiner, of which I never did receive an answer, I ask this same question. OF this supposedly Spontaneous generation of mammalian prions in this study, does this mean all sporadic CJD is spontaneous? does it mean half ? does in mean one third, one tenth, one hundredth, one thousandth, one millionth, just exactly what ? what does this really show ? Does this study show what many officials and industry is hoping, that it is all spontaneous mutation from nothing ? IF so, why did the authors of this study not explain this ? THERE is something terribly wrong with this prion and the UKBSEnvCJD only theory. It just does not compute, and I believe that this study raises more questions than answers. I believe that the authors of this study should have explained better whether or not this study shows that indeed all cases of sporadic CJD are of a spontaneous mutation cause, or not. They could have done a much better job of explaining what this study shows, or what it _does not_ show, and in my opinion, it damn sure does not show that all cases of sporadic CJD strains, and or atypical BSE strains arise spontaneously, a natural mutation, without any route and source of agent. But, this is what this study insinuates, and that is how it will be interpreted by industry groups and officials. I think the Authors of this study could have better interpreted that to the public, either way, either sporadic CJD is all spontaneous, or not, if not, how much is spontaneous. After 2+ decades of debating this, they owe the public this in my opinion. Stand Tall and tell us how much of this spontaneous mutation from nothing, how much of the 85% to 90% of all human TSE (well, maybe more than that IF you include the infamous sporadic FFI?) i.e. sporadic CJD, how much of this spontaneous mutation from nothing does this consist of ? 1 in a 100 cases, 1 in a thousand, 1 in a million, 1 in a billion, of sporadic CJD and sFFI cases etc. ? please tell me, or at least tell the public that this study does NOT insinuate what it does.
My reply and question to Professor Stanley Prusiner (of which he never would answer), the same question I now address to Julie A. Edgeworth, Nathalie Gros, Jack Alden, Susan Joiner, Jonathan D. F. Wadsworth, Jackie Linehan, Sebastian Brandner, Graham S. Jackson, Charles Weissmann1,2, and John Collinge1 + Author Affiliations. ...
REPORT ON MEASURES RELATING TO BOVINE SPONGIFORM ENCEPHALOPATHY (BSE) IN THE UNITED STATES Terry S. Singeltary Sr. February 11, 2004
Greetings,
as a lay person;-) i am thankful for Dr. Prusiners report below. I only wish that he would elaborate on the spontaneous aspect of sporadic CJD and how many of the 85%+ of all CJDs does he think happens spontaneously without route and source of the agent? I am concerned that people who read this, will come to the conclusion that all sporadic CJDs are a spontaneous mutation, when in reality all sporadic CJD is, is CJD from unknown route and source and they could be many. in fact, there could be many phenotypes of CJD that are now called sporadic CJD...
snip...full text ;
http://www.agobservatory.org/library.cfm?refID=30406
Stanley Prusiner comments January 27, 2004 ;
Statement from Stanley B. Prusiner, M.D., about 'Mad Cow' disease in the United States - January 27, 2004
Thank you, I am pleased to be here to address the Food Safety Caucus of the House of Representatives of the United States Congress about Mad Cow disease. I appear here as a concerned citizen, a loving parent, a dedicated physician specializing in Neurology, an educator who is a Professor of Neurology at the University of California, and scientist-businessman who is the Founder of InPro Biotechnology. I am also an expert on prion diseases, one of which is Mad Cow disease or bovine spongiform encephalopathy, often-abbreviated BSE. Both Federal and State Governments now find themselves embroiled over concerns over Mad Cow disease after Secretary of Agriculture, Ann Veneman, announced on December 23, 2003, that a 6.5-year-old cow from Mabton, Washington, had been diagnosed with Mad Cow disease. I would like to discuss five points concerning Mad Cow disease and what I believe should be done in our country to combat this malady.
1. Prions cause Mad Cow disease: First, Mad Cow disease is caused by an infectious agent that is so small that it cannot even be seen with the most powerful microscopes. These small infectious agents are called prions. Although large aggregates of prions can be studied with electron microscopes, we still cannot see the individual prions. For more than a century, viruses that can be seen in the electron microscope were the smallest known microbes. But, prions are much smaller than viruses and this extremely small size makes prions extremely difficult to kill.
2. Prion disease is always fatal: Second, prions cause severe destruction of the brain. The prion diseases of humans and animals are 100% fatal. Indeed, everyone with prion disease eventually dies. A single prion is sufficient to initiate the multiplication process that results in hundreds of prions being made followed by thousands, then millions and finally billions. It is well documented that billions of prions destroy the brain and spinal cord. From a wide variety of biomedical investigations, we know that prions from cattle can infect humans and destroy their brains. More than 150 teenagers and young adults in Europe have died of prion disease that they contracted after eating prion tainted beef or beef products.
3. Spontaneously induced prions: Third, prions arise spontaneously. This is an extremely important concept; furthermore, the ability to arise spontaneously is a feature that distinguishes prions from viruses. Any mammal is capable of producing prions spontaneously.
2
In humans, the most common form of prion disease results from the spontaneous formation of prions. Despite decades of looking for prions in the environment, there is no evidence for exposure to prions in spontaneous cases of prion disease.
The initial event in an epidemic of human prion disease referred to as kuru must have been a spontaneous case of prion disease. Once kuru prions arose spontaneously, they were propagated by ritualistic cannibalism that was practiced among New Guinea natives. While halting cannibalism of dead relatives resulted in the disappearance of kuru in a small population of natives, it did not eliminate the spontaneous formation of human prions. Similarly, stopping industrial cannibalism where cattle are fed the rendered offal of other cattle has diminished the number of cattle with BSE in Britain but will not prevent spontaneous prions from being formed. Thus, while changing feeding practices for cattle will stop the amplification of prions, it will not prevent the spontaneous formation of bovine prions.
As I said, prions can develop spontaneously within any mammal. We don't know what triggers this process but there are several reasonable hypotheses, one or more of which may eventually explain the spontaneous formation of prions.
4. The Japanese solution: Fourth, I cannot understand as the father of two daughters and the uncle of a niece and nephew why our country remains unwilling to adopt the Japanese policy of testing every cow and bull destined for consumption by humans. I have difficulty explaining to these young people that the beef in Japan is safer than that in the U.S.
The United States has the same problem that the Japan has, but the Japanese test all of the cattle that they slaughter. This issue particularly troubles children when they learn that the time from exposure to prions until the onset of neurological disease can exceed 50 years. Some New Guinea natives developed kuru more than 50 years after ingesting prions during cannibalistic feasts.
5. Prion science is new: Fifth, the science of prions is still very young. Only 25 years ago, I discovered prions and named these unprecedented infectious agents. Thus, the naysayers, who continue to deny the existence of prions, should not surprise you. A chorus of naysayers has always accompanied big changes in scientific thinking. When Galileo wrote about the planets orbiting the sun, he was imprisoned. How dare he think that the earth was not the center of universe? From the time that Einstein proposed his special theory of relatively in 1905 until his death 50 years later, the naysayers scorned him almost daily. Each week, at least two or three letters arrived at his Princeton office that declared him insane and his theories impossible. Only his death terminated this non-sense! Philip Semelweiss, a Viennese obstetrician, was eventually admitted to an insane asylum. Semelweiss was ridiculed mercilessly for proposing that his
3
colleagues could prevent deadly bacterial infections in mothers after childbirth if they would only wash their hands between the deliveries of newborn infants. And few believed Alfred Wagener when he proposed continental drift as a mechanism to explain the shapes and positions of the landmasses on our planet.
I recited a few instances of "scientific heresy" to place the discovery of prions in some perspective for you. For much of my career, I faced a legion of scientists who vehemently argued that prions couldn't exist! They yelled, "prions are nonsense. They are impossible!" Twenty-five years after my discovery of prions, there remain some people who are still unable or unwilling to comprehend the novel concepts of prion biology. The famous German physicist Max Planck encountered many naysayers when he and others set forth the principles of quantum mechanics. In frustration, Planck once remarked, "a new scientific truth does not win out by convincing its opponents, rather they eventually die off and a whole generation familiar with it grows up."
In non-scientific terms, prions must be considered new, strange and scary microbes by any measure. Twenty-five years ago, there were no prions – now the biology of prions is taught in every medical school throughout the world. Prion biology is also taught in many high schools and most colleges. Moreover, the word "prion" appears in every dictionary.
Because the discovery of prions ushered in major changes in our thinking, your duties as Congresswomen and Congressmen have and will continue to be subject to much misinformation with respect to Mad Cow disease. But I hasten to add that this is inevitable when an entirely new field of science emerges. Despite the fact that prions were once branded scientific heresy and are now considered orthodoxy by most scholars, the naysayers still exist. This means that you and your staff will hear some opinions that are not based on the body of scientific knowledge that has been accumulated over the past quarter century. Instead, you will hear views that ignore a constantly enlarging body of scientific information that has been verified by experimental studies.
Concluding remarks: In conclusion, from studies over the past half-century, we know that people should not eat prions, particularly prions of human or bovine origin. I want to reiterate that the problem of prion contamination in the food supply will not disappear. If we do nothing, confidence in the safety of food supply will only continue to erode. The sooner we face the problem of prion contamination, the more easily we shall be able to contain it. Only the Japanese solution of testing every slaughtered cow or bull will eliminate prions from the food supply and restore consumer confidence. Certainly, the citizens of the most prosperous and accomplished nation on our planet deserve to eat meat that is devoid of prions.
http://www.agobservatory.org/library.cfm?refID=30405
2010 atypical BSE
To date the OIE/WAHO assumes that the human and animal health standards set out in the BSE chapter for classical BSE (C-Type) applies to all forms of BSE which include the H-type and L-type atypical forms. This assumption is scientifically not completely justified and accumulating evidence suggests that this may in fact not be the case. Molecular characterization and the spatial distribution pattern of histopathologic lesions and immunohistochemistry (IHC) signals are used to identify and characterize atypical BSE. Both the L-type and H-type atypical cases display significant differences in the conformation and spatial accumulation of the disease associated prion protein (PrPSc) in brains of afflicted cattle. Transmission studies in bovine transgenic and wild type mouse models support that the atypical BSE types might be unique strains because they have different incubation times and lesion profiles when compared to C-type BSE. When L-type BSE was inoculated into ovine transgenic mice and Syrian hamster the resulting molecular fingerprint had changed, either in the first or a subsequent passage, from L-type into C-type BSE. In addition, non-human primates are specifically susceptible for atypical BSE as demonstrated by an approximately 50% shortened incubation time for L-type BSE as compared to C-type. Considering the current scientific information available, it cannot be assumed that these different BSE types pose the same human health risks as C-type BSE or that these risks are mitigated by the same protective measures.
http://www.prionetcanada.ca/detail.aspx?menu=5&dt=293380&app=93&cat1=387&tp=20&lk=no&cat2
Saturday, June 12, 2010
PUBLICATION REQUEST AND FOIA REQUEST Project Number: 3625-32000-086-05 Study of Atypical Bse
http://bse-atypical.blogspot.com/2010/06/publication-request-and-foia-request.html
14th International Congress on Infectious Diseases H-type and L-type Atypical BSE January 2010 (special pre-congress edition)
18.173 page 189
Experimental Challenge of Cattle with H-type and L-type Atypical BSE
A. Buschmann1, U. Ziegler1, M. Keller1, R. Rogers2, B. Hills3, M.H. Groschup1. 1Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany, 2Health Canada, Bureau of Microbial Hazards, Health Products & Food Branch, Ottawa, Canada, 3Health Canada, Transmissible Spongiform Encephalopathy Secretariat, Ottawa, Canada
Background: After the detection of two novel BSE forms designated H-type and L-type atypical BSE the question of the pathogenesis and the agent distribution of these two types in cattle was fully open. From initial studies of the brain pathology, it was already known that the anatomical distribution of L-type BSE differs from that of the classical type where the obex region in the brainstem always displays the highest PrPSc concentrations. In contrast in L-type BSE cases, the thalamus and frontal cortex regions showed the highest levels of the pathological prion protein, while the obex region was only weakly involved.
Methods:We performed intracranial inoculations of cattle (five and six per group) using 10%brainstemhomogenates of the two German H- and L-type atypical BSE isolates. The animals were inoculated under narcosis and then kept in a free-ranging stable under appropriate biosafety conditions.At least one animal per group was killed and sectioned in the preclinical stage and the remaining animals were kept until they developed clinical symptoms. The animals were examined for behavioural changes every four weeks throughout the experiment following a protocol that had been established during earlier BSE pathogenesis studies with classical BSE.
Results and Discussion: All animals of both groups developed clinical symptoms and had to be euthanized within 16 months. The clinical picture differed from that of classical BSE, as the earliest signs of illness were loss of body weight and depression. However, the animals later developed hind limb ataxia and hyperesthesia predominantly and the head. Analysis of brain samples from these animals confirmed the BSE infection and the atypical Western blot profile was maintained in all animals. Samples from these animals are now being examined in order to be able to describe the pathogenesis and agent distribution for these novel BSE types. Conclusions: A pilot study using a commercially avaialble BSE rapid test ELISA revealed an essential restriction of PrPSc to the central nervous system for both atypical BSE forms. A much more detailed analysis for PrPSc and infectivity is still ongoing.
http://www.isid.org/14th_icid/
http://ww2.isid.org/Downloads/IMED2009_AbstrAuth.pdf
http://www.isid.org/publications/ICID_Archive.shtml
14th ICID International Scientific Exchange Brochure -
Final Abstract Number: ISE.114
Session: International Scientific Exchange
Transmissible Spongiform encephalopathy (TSE) animal and human TSE in North America
update October 2009
T. Singeltary
Bacliff, TX, USA
Background:
An update on atypical BSE and other TSE in North America. Please remember, the typical U.K. c-BSE, the atypical l-BSE (BASE), and h-BSE have all been documented in North America, along with the typical scrapie's, and atypical Nor-98 Scrapie, and to date, 2 different strains of CWD, and also TME. All these TSE in different species have been rendered and fed to food producing animals for humans and animals in North America (TSE in cats and dogs ?), and that the trading of these TSEs via animals and products via the USA and Canada has been immense over the years, decades.
Methods:
12 years independent research of available data
Results:
I propose that the current diagnostic criteria for human TSEs only enhances and helps the spreading of human TSE from the continued belief of the UKBSEnvCJD only theory in 2009. With all the science to date refuting it, to continue to validate this old myth, will only spread this TSE agent through a multitude of potential routes and sources i.e. consumption, medical i.e., surgical, blood, dental, endoscopy, optical, nutritional supplements, cosmetics etc.
Conclusion:
I would like to submit a review of past CJD surveillance in the USA, and the urgent need to make all human TSE in the USA a reportable disease, in every state, of every age group, and to make this mandatory immediately without further delay. The ramifications of not doing so will only allow this agent to spread further in the medical, dental, surgical arena's. Restricting the reporting of CJD and or any human TSE is NOT scientific. Iatrogenic CJD knows NO age group, TSE knows no boundaries. I propose as with Aguzzi, Asante, Collinge, Caughey, Deslys, Dormont, Gibbs, Gajdusek, Ironside, Manuelidis, Marsh, et al and many more, that the world of TSE Transmissible Spongiform Encephalopathy is far from an exact science, but there is enough proven science to date that this myth should be put to rest once and for all, and that we move forward with a new classification for human and animal TSE that would properly identify the infected species, the source species, and then the route.
see page 114 ;
http://ww2.isid.org/Downloads/14th_ICID_ISE_Abstracts.pdf
Sent: Friday, April 16, 2010 11:38 AM Subject: PRO-MED ATYPICAL SCRAPIE
Background ----------- "Retrospective studies have identified cases predating the initial identification of this form of scrapie, and epidemiological studies have indicated that it does not conform to the behaviour of an infectious disease, giving rise to the hypothesis that it represents spontaneous disease. However, atypical scrapie isolates have been shown to be infectious experimentally, through intracerebral inoculation in transgenic mice and sheep. [Many of the neurological diseases can be transmitted by intracerebral inoculation, which causes this moderator to approach intracerebral studies as a tool for study, but not necessarily as a direct indication of transmissibility of natural diseases. - Mod.TG]
"The 1st successful challenge of a sheep with 'field' atypical scrapie from an homologous donor sheep was reported in 2007.
"Results -------- "This study demonstrates that atypical scrapie has distinct clinical, pathological, and biochemical characteristics which are maintained on transmission and sub-passage, and which are distinct from other strains of transmissible spongiform encephalopathies in the same host genotype.
"Conclusions ------------ Atypical scrapie is consistently transmissible within AHQ homozygous sheep, and the disease phenotype is preserved on sub-passage."
Lastly, this moderator wishes to thank Terry Singletary for some of his behind the scenes work of providing citations and references for this posting. - Mod.TG]
The HealthMap/ProMED-mail interactive map of Australia is available at <http://healthmap.org/r/00co>. - Sr.Tech.Ed.MJ]
http://www.promedmail.org/pls/otn/f?p=2400:1001:962575216785367::NO::F2400_P1001_BACK_PAGE,F2400_P1001_PUB_MAIL_ID:1000,81729
Archive Number 20100405.1091 Published Date 05-APR-2010
Subject PRO/AH/EDR> Prion disease update 1010 (04)
snip...
[Terry S. Singeltary Sr. has added the following comment:
"According to the World Health Organisation, the future public health threat of vCJD in the UK and Europe and potentially the rest of the world is of concern and currently unquantifiable. However, the possibility of a significant and geographically diverse vCJD epidemic occurring over the next few decades cannot be dismissed
<http://whqlibdoc.who.int/publications/2003/9241545887.pdf>.
The key word here is diverse. What does diverse mean? If USA scrapie transmitted to USA bovine does not produce pathology as the UK c-BSE, then why would CJD from there look like UK vCJD?"
http://www.promedmail.org/pls/apex/f?p=2400:1001:568933508083034::NO::F2400_P1001_BACK_PAGE,F2400_P1001_PUB_MAIL_ID:1000,82101
Monday, March 29, 2010
CJD TEXAS 38 YEAR OLD FEMALE WORKED SLAUGHTERING CATTLE EXPOSED TO BRAIN AND SPINAL CORD MATTER
>>> Up until about 6 years ago, the pt worked at Tyson foods where she worked on the assembly line, slaughtering cattle and preparing them for packaging. She was exposed to brain and spinal cord matter when she would euthanize the cattle. <<<
http://recordandoalinda.com/index.php?option=com_content&view=article&id=19&Itemid=8
http://www.recordandoalinda.com/index.php?option=com_content&view=article&id=2:frontpage&catid=1:frontpage
WHY IS IT THE 'GOLD STANDARD' TO IGNORE THIS SCIENCE $$$
2008
Emerg Infect Dis. 2008 December; 14(12): 1898-1901. doi: 10.3201/eid1412.080941. PMCID: PMC2634647
Copyright notice
Transmission of Atypical Bovine Prions to Mice Transgenic for Human Prion Protein
Vincent Béringue, Laëtitia Herzog, Fabienne Reine, Annick Le Dur, Cristina Casalone, Jean-Luc Vilotte, and Hubert Laude Institut National de la Recherche Agronomique, Jouy-en-Josas, France (V. Béringue, L. Herzog, F. Reine, A. Le Dur, J.-L. Vilotte, H. Laude) Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Turin, Italy (C. Casalone) Corresponding author. Address for correspondence: Vincent Béringue, Institut National de la Recherche Agronomique, UR892, Virologie Immunologie Moléculaires, F-78350 Jouy-en-Josas, France; email:
[email protected]. This article has been cited by other articles in PMC. Abstract To assess risk for cattle-to-human transmission of prions that cause uncommon forms of bovine spongiform encephalopathy (BSE), we inoculated mice expressing human PrP Met129 with field isolates. Unlike classical BSE agent, L-type prions appeared to propagate in these mice with no obvious transmission barrier. H-type prions failed to infect the mice.
Keywords: prions, BSE, PrP, strains, transgenic mice, dispatch
Abstract
The epizootic of bovine spongiform encephalopathy (BSE) is under control in European countries >20 years after the first cases were diagnosed in the United Kingdom. Thus far, BSE is the only animal prion disease known to have been transmitted to humans, leading to a variant form of Creutzfeldt-Jakob disease (vCJD) (1). The large-scale testing of livestock nervous tissues for the presence of protease-resistant prion protein (PrPres) has enabled assessment of BSE prevalence and exclusion of BSE-infected animals from human food (2). This active surveillance has led to the recognition of 2 variant PrPres molecular signatures, termed H-type and L-type BSE. They differ from that of classical BSE by having protease-resistant fragments of a higher (H) or a slightly lower (L) molecular mass, respectively, and different patterns of glycosylation (3-5). Both types have been detected worldwide as rare cases in older animals, at a low prevalence consistent with the possibility of sporadic forms of prion diseases in cattle (6). Their experimental transmission to mice transgenic for bovine PrP demonstrated the infectious nature of such cases and the existence of distinct prion strains in cattle (5,7-9). Like the classical BSE agent, H- and L-type prions can propagate in heterologous species (7-11). Thus, both agents are transmissible to transgenic mice expressing ovine PrP (VRQ allele). Although H-type molecular properties are conserved on these mice (9), L-type prions acquire molecular and neuropathologic phenotypic traits undistinguishable from BSE or BSE-related agents that have followed the same transmission history (7). Similar findings have been reported in wild-type mice (8). An understanding of the transmission properties of these newly recognized prions when confronted with the human PrP sequence is needed. In a previous study, we measured kinetics of PrPres deposition in the brain to show that L-type prions replicate faster than BSE prions in experimentally inoculated mice that express human PrP (7). In a similar mouse model, the L-type agent (alternatively named BASE) was also shown to produce overt disease with an attack rate of ~30% (12). However, no strict comparison with BSE agent has been attempted. As regards the H-type agent, its potential virulence for mice that express human PrP Met129 remains to be assessed. We now report comparative transmission data for these atypical and classical BSE prions.
snip...
Conclusions
We found that atypical L-type bovine prions can propagate in human PrP transgenic mice with no significant transmission barrier. Lack of a barrier is supported by the 100% attack rate, the absence of reduction of incubation time on secondary passage, and the conservation of PrPres electrophoretic profile. In comparison, transmission of classical BSE agent to the same mice showed a substantial barrier. Indeed, 3 passages were necessary to reach a degree of virulence comparable to that of vCJD agent in these mice (13), which likely reflects progressive adaptation of the agent to its new host. At variance with the successful transmission of classical BSE and L-type agents, H-type agent failed to infect tg650 mice. These mice overexpress human PrP and were inoculated intracranially with a low dilution inoculum (10% homogenate). Therefore, this result supports the view that the transmission barrier of BSE-H from cattle to humans might be quite robust. It also illustrates the primacy of the strain over PrP sequence matching for cross-species transmission of prions (15). Extrapolation of our data raises the theoretical possibility that the zoonotic risk associated with BSE-L prions might be higher than that associated with classical BSE, at least for humans carrying the Met129 PrP allele. This information underlines the need for more intensive investigations, in particular regarding the tissue tropism of this agent. Its ability to colonize lymphoid tissues is a potential, key factor for a successful transmission by peripheral route. This issue is currently being explored in the tg650 mice. Although recent data in humanized mice suggested that BSE-L agent is likely to be lymphotropic (12), preliminary observations in our model suggested that its ability to colonize such tissues is comparatively much lower than that of classical BSE agent.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2634647/
2002
BSE prions propagate as either variant CJD-like or sporadic CJD-like prion strains in transgenic mice expressing human prion protein
Emmanuel A. Asante, Jacqueline M. Linehan, Melanie Desbruslais, Susan Joiner, Ian Gowland, Andrew L. Wood, Julie Welch, Andrew F. Hill, Sarah E. Lloyd, Jonathan D.F. Wadsworth, and John Collinge1 MRC Prion Unit and Department of Neurodegenerative Disease, Institute of Neurology, University College, Queen Square, London WC1N 3BG, UK 1Corresponding author e-mail:
[email protected]. August 1, 2002; Revised September 24, 2002; Accepted October 17, 2002. This article has been cited by other articles in PMC. Other Sections?
Abstract
Variant Creutzfeldt-Jakob disease (vCJD) has been recognized to date only in individuals homozygous for methionine at PRNP codon 129. Here we show that transgenic mice expressing human PrP methionine 129, inoculated with either bovine spongiform encephalopathy (BSE) or variant CJD prions, may develop the neuropathological and molecular phenotype of vCJD, consistent with these diseases being caused by the same prion strain. Surprisingly, however, BSE transmission to these transgenic mice, in addition to producing a vCJD-like phenotype, can also result in a distinct molecular phenotype that is indistinguishable from that of sporadic CJD with PrPSc type 2. These data suggest that more than one BSE-derived prion strain might infect humans; it is therefore possible that some patients with a phenotype consistent with sporadic CJD may have a disease arising from BSE exposure.
Keywords: BSE/Creutzfeldt-Jakob disease/prion/transgenic
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC136957/?tool=pubmed
2004
Originally published in Science Express on 11 November 2004 Science 3 December 2004: Vol. 306. no. 5702, pp. 1793 - 1796 DOI: 10.1126/science.1103932
Reports Human Prion Protein with Valine 129 Prevents Expression of Variant CJD Phenotype Jonathan D. F. Wadsworth, Emmanuel A. Asante, Melanie Desbruslais, Jacqueline M. Linehan, Susan Joiner, Ian Gowland, Julie Welch, Lisa Stone, Sarah E. Lloyd, Andrew F. Hill,* Sebastian Brandner, John Collinge
Variant Creutzfeldt-Jakob disease (vCJD) is a unique and highly distinctive clinicopathological and molecular phenotype of human prion disease associated with infection with bovine spongiform encephalopathy (BSE)-like prions. Here, we found that generation of this phenotype in transgenic mice required expression of human prion protein (PrP) with methionine 129. Expression of human PrP with valine 129 resulted in a distinct phenotype and, remarkably, persistence of a barrier to transmission of BSE-derived prions on subpassage. Polymorphic residue 129 of human PrP dictated propagation of distinct prion strains after BSE prion infection. Thus, primary and secondary human infection with BSE-derived prions may result in sporadic CJD-like or novel phenotypes in addition to vCJD, depending on the genotype of the prion source and the recipient.
Medical Research Council (MRC) Prion Unit and Department of Neurodegenerative Disease, Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
* Present address: Department of Biochemistry and Molecular Biology and Department of Pathology, University of Melbourne, Parkville, Victoria 3010, Australia.
To whom correspondence should be addressed. E-mail:
[email protected].
http://www.sciencemag.org/cgi/content/abstract/306/5702/1793
2008
Prominent and Persistent Extraneural Infection in Human PrP Transgenic Mice Infected with Variant CJD
The evolution of the variant Creutzfeldt-Jakob disease (vCJD) epidemic is hazardous to predict due to uncertainty in ascertaining the prevalence of infection and because the disease might remain asymptomatic or produce an alternate, sporadic-like phenotype.
Transgenic mice were produced that overexpress human prion protein with methionine at codon 129, the only allele found so far in vCJD-affected patients. These mice were infected with prions derived from variant and sporadic CJD (sCJD) cases by intracerebral or intraperitoneal route, and transmission efficiency and strain phenotype were analyzed in brain and spleen. We showed that i) the main features of vCJD infection in humans, including a prominent involvement of the lymphoid tissues compared to that in sCJD infection were faithfully reproduced in such mice; ii) transmission of vCJD agent by intracerebral route could lead to the propagation of either vCJD or sCJD-like prion in the brain, whereas vCJD prion was invariably propagated in the spleen, iii) after peripheral exposure, inefficient neuroinvasion was observed, resulting in an asymptomatic infection with life-long persistence of vCJD prion in the spleen at stable and elevated levels.
Our findings emphasize the possibility that human-to-human transmission of vCJD might produce alternative neuropathogical phenotypes and that lymphoid tissue examination of CJD cases classified as sporadic might reveal an infection by vCJD-type prions. They also provide evidence for the strong propensity of this agent to establish long-lasting, subclinical vCJD infection of lymphoreticular tissues, thus amplifying the risk for iatrogenic transmission.
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Discussion Top In this study we used tg650 mice, a newly developed transgenic line expressing human PrPC, to investigate some aspects of the pathogenesis of vCJD infection. As main findings, we demonstrate that prion strain divergence can occur upon transmission of human, primary vCJD to such mice, and that peripheral challenge leads to an asymptomatic, life-long infection of the lymphoid compartment. A feature of tg650 mice is that following primary intracerebral vCJD challenge they developed a neurological disease with typically 100% attack rate, unlike for previously established PrP129Met, including overexpressing lines [16], [19]. The mean survival time - typically around 500 days in homozygous mice - did not change notably on subpassaging, implying that vCJD agent might clinically infect the tg650 mice with little or no transmission barrier. This discrepant result may reflect the use of different constructs and genetic backgrounds (Text S1), and the transgene expression levels, although the latter does not seem to greatly differ as far as the tg650+/- and tg45 mice [16] are concerned.
A surprising result of these studies is the alternate pattern of disease that was induced by one of the inoculated vCJD cases, a WHO reference case here designated vCJD no. 4. Indeed, while vCJD strain features were faithfully propagated in the majority of tg650 mice, almost half of the vCJD 4-inoculated mice were found to propagate a prion replicating faster than vCJD agent, and exhibiting sCJD-like PrPres and neuropathological features. Although strain divergence upon transmission of BSE/vCJD agent to mice was reported to occur in earlier studies [16], [24], it was unprecedented within a context of homotypic transmission, i.e. full matching between the donor and receiver PrP sequences. To address the issue of a possible contamination, we performed independent transmission experiments, involving separate inoculum batches of the incriminated case, which all produced consistent results. Therefore, we consider the data inconsistent with contamination of the VCJD no. 4 material by a sCJD infectious source within our laboratory. An alternate possibility, i.e. a cross-contamination of the source material, was judged highly improbable owing to the procedures applied during the collect of the specimen and the preparation of the homogenates ([25] and P. Minor, personal communication). On the other hand, our observation intriguingly parallels the phenotypic disjunction observed upon transmission of BSE agent to human PrP129Met mice (tg35 line [16]). Together, these findings lend support to the hypothesis that a minor strain component might be created upon cattle-to-human transmission of BSE agent and could emerge upon subsequent human-to-human transmission. It is also worth mentioning that, while the probability to detect such a variant through mouse bioassay would be expected to depend on the amount - and possibly the regions - of brain tissue taken to establish the source material, the vCJD-4 homogenate was prepared using a larger amount of tissue from the same brain than for the other homogenates analyzed in this study (i.e. 100 mg instead of 1 mg of frontal cortex [25]).
The above finding has obvious implications in terms of public health as it raises the concern that some humans iatrogenically infected by vCJD agent may develop a clinical disease that would not be recognized as of vCJD origin [17], [26]. Strikingly however, all vCJD-4-inoculated mice, notwithstanding the strain phenotype divergence propagated bona fide vCJD agent in their spleen, based on the PrPres pattern and the disease phenotype produced by secondary transmission to tg650 mice. This result is of direct relevance to the diagnosis of variant and sporadic CJD. Indeed, looking for peripheral lymphoreticular deposition of abnormal PrP on cases diagnosed as sporadic CJD might reveal a vCJD infection resulting from human-to-human, or cattle-to-human transmission. In this respect, it would be of interest to examine whether BSE-inoculated tg35 mice showing discordant PrPres signatures [16], or vCJD-challenged PrP129Val transgenic mice producing 'type 5' prion in their brain [17] do accumulate PrPvCJD in their spleens. In any case, our findings provide clear evidence that, as a consequence of strain-related tropism disparities, the same mouse can propagate different prions in different tissues following a single infection event.
Another salient finding emerging from this study was the remarkable ability of vCJD agent to establish asymptomatic infection despite sustained, life-long propagation in extraneural tissues. When challenged peripherally, tg650 mice remained asymptomatic over the whole observation period, and did not accumulate PrPres at detectable levels in their brain before 750 days pi, near the life end-stage. In the spleen of these mice however, PrPres accumulation reached its maximum at an early stage of infection, and remained at stable and substantial levels until death. Plateauing of prion infection in the spleen is consistent with earlier observations, and has been suggested to reflect an exhaustion of target cells (for review [22]) Importantly, the spleen tissue was highly infectious as it killed 100% of intracerebrally challenged mice within the minimal mean incubation time (~500 days). Altogether these data support the view that the sustained multiplication of the vCJD prion in lymphoid tissues was not accompanied by an efficient neuroinvasion in tg650 mice. Such an extremely delayed neuroinvasion appears to be rare in TSE rodent models, and to our knowledge was only reported for the mouse-adapted strain 87V on IM mice infected intraperitoneally with diluted inoculum [27]. Clearly, while early accumulation of prions in lymphoid tissues may be essential for efficient neuroinvasion [22], efficient lymphoinvasion does not inevitably lead to rapid neuroinvasion. This finding strengthens the notion that humans infected by vCJD from a human source - including individuals of the MM genotype - might remain clinically asymptomatic for a very prolonged period of time while harboring relatively high levels of prion infectivity in their lymphoid tissues from an early stage of infection on, thereby amplifying the risk of iatrogenic transmission. It also supports the view that the large-scale survey of lymphoreticular tissues [28] may lead to a reliable assessment of the actual prevalence of vCJD infection in the UK population.
Finally, the human PrP transgenic model described in this study may help to further our understanding of peripheral vCJD pathogenesis, for instance in trying to identify factors that might enhance neuroinvasion efficiency, or modulate the shedding of prion infectivity from the lymphoreticular to the blood compartment. Moreover, preliminary results indicate that the search for abnormal PrP in the spleen of such mice culled at time intervals post infection [29], [30] could allow the detection of low levels of vCJD infectivity within a reasonably short time scale.
Citation: Béringue V, Le Dur A, Tixador P, Reine F, Lepourry L, et al. (2008) Prominent and Persistent Extraneural Infection in Human PrP Transgenic Mice Infected with Variant CJD. PLoS ONE 3(1): e1419. doi:10.1371/journal.pone.0001419
Academic Editor: Adam Ratner, Columbia University, United States of America
Received: September 20, 2007; Accepted: December 17, 2007; Published: January 9, 2008
Copyright: © 2008 Beringue et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This work was supported by INRA, Institut de Veille Sanitaire (InVS) and the Ministry of Research, France. The sponsors of this study had no role in study conduct, collection analysis, interpretation of the data, writing of the report or approval of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
* To whom correspondence should be addressed. E-mail:
[email protected]. (HL);
[email protected]. (VB)
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0001419
THESE ELECTRODES, and infection there from during neurosurgery, were not of a spontaneous nature ;
1: J Neurol Neurosurg Psychiatry 1994 Jun;57(6):757-8
Transmission of Creutzfeldt-Jakob disease to a chimpanzee by electrodes contaminated during neurosurgery.
Gibbs CJ Jr, Asher DM, Kobrine A, Amyx HL, Sulima MP, Gajdusek DC.
Laboratory of Central Nervous System Studies, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892.
Stereotactic multicontact electrodes used to probe the cerebral cortex of a middle aged woman with progressive dementia were previously implicated in the accidental transmission of Creutzfeldt-Jakob disease (CJD) to two younger patients. The diagnoses of CJD have been confirmed for all three cases. More than two years after their last use in humans, after three cleanings and repeated sterilisation in ethanol and formaldehyde vapour, the electrodes were implanted in the cortex of a chimpanzee. Eighteen months later the animal became ill with CJD. This finding serves to re-emphasise the potential danger posed by reuse of instruments contaminated with the agents of spongiform encephalopathies, even after scrupulous attempts to clean them.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8006664&dopt=Abstract
SPONTANEOUS TSE
Perspectives BIOMEDICINE: A Fresh Look at BSE Bruce Chesebro*
Mad cow disease, or bovine spongiform encephalopathy (BSE), is the cattle form of a family of progressive brain diseases. These diseases include scrapie in sheep, Creutzfeldt-Jakob disease (CJD) in humans, and chronic wasting disease (CWD) in deer and elk. They are also known as either "prion diseases" because of the association of a misfolded cellular prion protein in pathogenesis or "transmissible spongiform encephalopathies" (TSEs) because of the spongelike nature of the damaged brain tissue (1).
The recent discovery of two BSE-infected cows, one in Canada and one in the United States, has dramatically increased concern in North America among meat producers and consumers alike over the extent to which BSE poses a threat to humans as well as to domestic and wild animals. The European BSE epidemic of the late-1980s seems to have been initiated a decade earlier in the United Kingdom by changes in the production of meat and bone meal (MBM) from rendered livestock, which led to contamination of MBM with the BSE infectious agent. Furthermore, the fact that UK farmers fed this rendered MBM to younger animals and that this MBM was distributed to many countries may have contributed to the ensuing BSE epidemic in the United Kingdom and internationally (2).
Despite extensive knowledge about the spread of BSE through contaminated MBM, the source of BSE in Europe remains an unsolved mystery (2). It has been proposed that BSE could be derived from a cross-species infection, perhaps through contamination of MBM by scrapie-infected sheep tissues (see the figure). Alternatively, BSE may have been an endemic disease in cattle that went unnoticed because of its low level of horizontal transmission. Lastly, BSE might have originated by "spontaneous" misfolding of the normal cellular prion protein into the disease-associated abnormal isoform (3), which is postulated to be the infectious agent or "prion."
Five possible sources of BSE in North American cattle. Sheep, deer, and elk could spread prion diseases (TSEs) to cattle through direct animal contact or contamination of pastures. Endemic BSE has not been proven to exist anywhere in the world, but it is difficult to exclude this possibility because of the inefficient spread of BSE infectivity between individual animals (2). BSE caused by spontaneous misfolding of the prion protein has not been proven. CREDIT: KATHARINE SUTLIFF/SCIENCE
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Nevertheless, the idea that BSE might originate due to the spontaneous misfolding of prion proteins has received renewed interest in the wake of reports suggesting the occurrence of atypical BSE (9-11). These results imply that new strains of cattle BSE might have originated separately from the main UK outbreak. Where and how might such strains have originated? Although such rare events cannot be studied directly, any number of sources of the original BSE strain could also explain the discovery of additional BSE strains in cattle (see the figure). However, it would be worrisome if spontaneous BSE were really a valid etiology because such a mechanism would be impossible to prevent--unlike other possible scenarios that could be controlled by large-scale eradication of TSE-positive animals.
Another way to look at this problem is to examine evidence for possible spontaneous TSE disease in other animals besides cattle. Spontaneous BSE would be extremely difficult to detect in cattle, where horizontal spread is minimal. However, in the case of the sheep TSE disease, scrapie, which spreads from ewes to lambs at birth as well as between adults, spontaneous disease should be detectable as new foci of clinical infection. In the early 1950s scrapie was eradicated in both Australia and New Zealand, and the mainland of both these countries has remained scrapie-free ever since. This scrapie-free status is not the result of selection of sheep resistant to scrapie because sheep from New Zealand are as susceptible as their UK counterparts to experimental scrapie infection (12). These experiments of man and nature appear to indicate that spontaneous clinical scrapie does not occur in sheep. Similarly, because CWD is known to spread horizontally, the lack of CWD in the deer or elk of eastern North America but its presence in western regions would also argue against a spontaneous disease mechanism. This is particularly noteworthy in New Zealand, where there are large numbers of deer and elk farms and yet no evidence of spontaneous CWD. If spontaneous scrapie does not occur in sheep or deer, this would suggest that spontaneous forms of BSE and sporadic Creutzfeldt-Jakob disease (sCJD) are unlikely to be found in cattle or humans. The main caveat to this notion is that spontaneous disease may arise in some animal species but not others. In humans, sCJD--which is considered by some researchers to begin by spontaneous misfolding of the prion protein--usually takes more than 50 years to appear. Thus, in animals with a shorter life-span, such as sheep, deer, and cattle, an analogous disease mechanism might not have time to develop.
What can we conclude so far about BSE in North America? Is the BSE detected in two North American cows sporadic or spontaneous or both? "Sporadic" pertains to the rarity of disease occurrence. "Spontaneous" pertains to a possible mechanism of origin of the disease. These are not equivalent terms. The rarity of BSE in North America qualifies it as a sporadic disease, but this low incidence does not provide information about cause. For the two reported North American BSE cases, exposure to contaminated MBM remains the most likely culprit. However, other mechanisms are still possible, including cross-infection by sheep with scrapie or cervids with CWD, horizontal transmission from cattle with endemic BSE, and spontaneous disease in individual cattle. Based on our understanding of other TSEs, the spontaneous mechanism is probably the least likely. Thus, "idiopathic" BSE--that is, BSE of unknown etiology--might be a better term to describe the origin of this malady. ...
snip...full text ;
http://www.sciencemag.org/cgi/content/full/sci;305/5692/1918
Release No. 0106.04
Contact: Office of Communications (202) 720-4623
Transcript of Remarks From Technical Briefing on BSE and Related Issues With Agriculture Secretary Ann M. Veneman and USDA Chief Veterinary Officer Dr. Ron DeHaven Washington D.C. - March 15, 2004
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OPERATOR : "Yes. Our next one is coming from Elizabeth Weiss. Please state your company."
ELIZABETH WEISS: "This is Elizabeth Weiss with USA Today."
"I actually had two questions. First off, when you say you're looking for 1 in 10,000 cases, is USDA doing any work to find out the possibility of whether or not BSE exists in a spontaneous form in the way that it does in humans and elk populations?
"And secondly, how will any of this fit into some of the consternation that's been raised in California and with the Midwest packer that wanted to test all of its cattle?
"Thanks."
DR. DEHAVEN: "All right. I think we've got three different questions in there, and I'll try to touch on each one of them.
"First of all, let me correct just a technical issue, and that is you mentioned 1 in 10,000. And actually our surveillance system currently is designed, the one that we have in place now is designed to detect 1 positive in 1 million cattle, and I gave some numbers between 200,000 and 268,000 that would allow us to detect 1 in 10 million as opposed to 1 in 10,000.
"So we would, if we were able to collect in the ballpark of those numbers of samples then we with increasing numbers of samples have an increasingly statistically valid sample from which to determine, one, whether or not the disease exists and, if so, at what prevalence level.
"So our real emphasis is to test as many of those animals as we can, ensure that we get an appropriate geographical distribution, but not setting a specific number as far as a target. Again, consistent with the recommendation from the International Review Team, their recommendation was to test all of them.
"So that's consistent with where we're going is to test as many as we possibly can.
"As far as spontaneous cases, that is a very difficult issue. There is no evidence to prove that spontaneous BSE occurs in cattle; but here again it's an issue of proving a negative. We do know that CJD, the human version of the disease, does occur spontaneously in humans at the rate of about 1 in 1 million. We don't have enough data to definitively say that spontaneous cases of BSE in cattle occur or do not occur.
"Again, it's a very difficult situation to prove a negative.
"So a lot of research is ongoing. Certainly if we do come up with any positive samples in the course of this surveillance we will be looking at that question in evaluating those samples but no scientifically hard evidence to confirm or refute whether or not spontaneous cases of BSE occur.
snip...
http://www.usda.gov/wps/portal/!ut/p/_s.7_0_A/7_0_1OB?contentidonly=true&contentid=2004/03/0106.html
P2-110
TRANSMISSION OF ATYPICAL BOVINE SPONGIFORM ENCEPHALOPATHY TO MICROCEBUS MURINUS, A NON-HUMAN PRIMATE. DEVELOPMENT OF CLINICAL SYMPTOMS AND TISSUE DISTRIBUTION OF PRPRES
Nadine Mestre-Frances1, Anne-Gaelle Biacabe2, Sylvie Rouland1, Thierry Baron2, Jean-Michel Verdier1, 1INSERM U710, Montpellier, France; 2AFSSA, Lyon, France. Contact e-mail: nfrances@univmontp2. fr
Background: Atypical BSE cases have been observed in Europe, Japan and North America. They differ in their PrPres profiles from those found in classical BSE. These atypical cases fall into 2 types, depending on the molecular mass of the unglycosylated PrPres band observed by Western blot: the L-type (lower molecular mass than the typical BSE cases) and H-type (higher molecular mass than the typical BSE cases).
Methods: Height animals (4 males and 4 females) were intracerebrally inoculated with 50 l of a 10% brain homogenates of atypical (L and H-type) French BSE cases.
Results: Only one of the four lemurs challenge with H-type BSE died without clinical signs after 19 months post inoculation (mpi), the 4 animals inoculated with L-type BSE died at 19 mpi (2 males) and 22 mpi (2 females). Three months before their sacrifice, they developed blindness, tremor, abnormal posture, incoordinated movements, balance loss. Symptoms get worse according to the disease progression, until severe ataxia. The brain tissue were biochemically and immunocytochemically investigated for PrPres. For the H-types, spongiform changes without PrPres accumulation were observed in the brainstem. Western blot analysis confirmed that no PrPres was detected into the brain. For the L-types, severe spongiosis was evidenced into the thalamus, the striatum, the mesencephalon, and the brainstem, whereas into the cortex the spongiosis was evidenced, but the vacuolisation was weaker. Strong deposits of PrPres was detected by western blot, PET-blot and immunocytochemistry in the CNS: dense accumulation was observed into the thalamus, the striatum, and the hippocampus whereas in the cerebral cortex, PrPres was prominently accumulated in plaques. Western blot analysis confirmed the presence of protease-resistant prion protein.
Conclusions: L-type infected lemurs showed survival times considerably shorter than for classical BSE strain, indicating that the disease is caused by a very virulent distinct prion strain.
http://download.journals.elsevierhealth.com/pdfs/journals/1552-5260/PIIS1552526008013447.pdf
>>> Conclusions: L-type infected lemurs showed survival times considerably shorter than for classical BSE strain, indicating that the disease is caused by a very virulent distinct prion strain. >>>
seems the survival time was the same for the h-type BSE and the l-type BSE i.e. 19 months post inoculation (mpi), interesting. ...TSS
Wednesday, March 31, 2010
Atypical BSE in Cattle / position: Post Doctoral Fellow
http://bse-atypical.blogspot.com/2010/03/atypical-bse-in-cattle-position-post.html
Wednesday, February 24, 2010
Transmissible Spongiform encephalopathy (TSE) animal and human TSE in North America 14th
ICID International Scientific Exchange Brochure -
http://transmissiblespongiformencephalopathy.blogspot.com/2010/02/transmissible-spongiform-encephalopathy.html
Saturday, June 12, 2010
PUBLICATION REQUEST AND FOIA REQUEST Project Number: 3625-32000-086-05 Study of Atypical Bse
http://bse-atypical.blogspot.com/2010/06/publication-request-and-foia-request.html
Saturday, July 17, 2010
Variant Creutzfeldt-Jakob disease Ironside JW., Haemophilia. 2010 Jul;16 Suppl 5:175-80
REVIEW ARTICLE
http://vcjdtransfusion.blogspot.com/2010/07/variant-creutzfeldtjakob-disease.html
Saturday, June 19, 2010
U.S. DENIED UPGRADED BSE STATUS FROM OIE
see full text and reasons why here ;
http://usdameatexport.blogspot.com/2010/06/us-denied-upgraded-bse-status-from-oie.html
TSS
Tuesday, July 27, 2010
Spontaneous generation of mammalian prions
http://madcowspontaneousnot.blogspot.com/2010/07/spontaneous-generation-of-mammalian.html
