Friday, March 30, 2018

Detection of Creutzfeldt-Jakob disease prions in skin: implications for healthcare

Detection of Creutzfeldt-Jakob disease prions in skin: implications for healthcare 

Akin NihatView ORCID ID profile and Simon MeadEmail author Genome Medicine201810:22 https://doi.org/10.1186/s13073-018-0536-3© The Author(s). 2018 Published: 26 March 2018 

Editorial 

summary 

Evidence has recently been reported of prion seeding activity in skin tissue from patients with sporadic Creutzfeldt-Jakob disease (sCJD). This is relevant information for infection control measures during surgery. The work uses very sensitive prion assays now available for medical research, and may soon be adapted to related neurodegenerative disorders.

Prion diseases Prion diseases are a group of incurable neurodegenerative disorders marked by the accumulation of misfolded forms of the normal cellular prion protein (PrP). The concept of a proteinaceous pathogen or ‘prion’ responsible for the transmissibility of the diseases, although initially controversial, has become an influential concept in neurodegeneration research, but it is still unclear exactly which structures of abnormal PrP behave as prions. The most common human prion disease, sCJD, occurs at random in the population. However, this disease group is notorious for acquired forms: zoonotic variant CJD (vCJD) arises following dietary exposure to bovine spongiform encephalopathy (BSE) prions; and iatrogenic CJD arises from exposure to prions as a result of a medical procedure. Procedures known to have caused iatrogenic CJD include the use of cadaveric growth hormone, dura mater grafts, and, especially pertinent to a discussion about prions in skin, surgical instruments. Extensive measures are taken to prevent patient exposures to prions during medical or surgical procedures in those asymptomatically infected, or with early but unrecognised symptoms. Acquired prion diseases are very rare. In 2017, 113 deaths were recorded in the UK from definite or probable prion diseases, but none of these cases were thought to be acquired (National CJD Research and Surveillance Unit data, https://www.cjd.ed.ac.uk/).

Evidence for prions in skin Animal bioassay is the only method to definitively demonstrate prion infectivity, but these are expensive and time-consuming experiments. Many factors affect the efficiency of transmission in an experiment: inoculation route, PrP expression level of the inoculated animal, prion strain (comparable to virus strain), and the degree of homology in the primary sequence of PrP between host and inoculum. By varying these factors, experiments can be designed to optimise sensitivity, or model medical situations more realistically. Recently, Orrú and colleagues [1] demonstrated, for the first time, gold-standard evidence for the presence of human prions in skin, using a transmission study tuned to be sensitive: by intracerebral inoculation of inocula made from the skin of two patients with CJD, into mice that were engineered to express the human form of PrP.

Surrogate methods were also used to infer the presence of prions in skin tissue. These methods do not directly measure prion titres or infectivity but are fast, inexpensive, and sensitive. The disease process generates a multitude of abnormal forms of prion protein that can be either infectious or non-infectious. Many abnormal forms of prion protein have distinct biochemical properties such as relative protease resistance and staining properties of amyloid protein aggregates, and can be detected by histology or partial protease digestion and Western blotting. Orrú et al. [1] found only a faint PrP-immunoreactive band by Western blot from one of five sCJD patients despite using enhanced detection techniques. This finding is broadly consistent with previous studies [2].

More significantly, Orrú et al. [1] employed in vitro prion ‘seeding’ assays, which are able to detect miniscule amounts of disease-associated prion protein (~femtograms). The real-time quaking-induced conversion (RTQuIC) assay exploits the ability of disease-associated prion protein to template the misfolding of recombinant PrP through repeated cycles of mechanical agitation intended to break apart the forming amyloid. In a blinded analysis, Orrú et al. [1] demonstrated by RTQuIC the presence of prion protein amyloid in at least one of three skin samples from all 23 CJD patients with either vCJD or sCJD, but not in skin from any non-CJD control individuals. The concentrations of RTQuIC seeding activity were 1000- to 100,000-fold lower in skin than brain tissue from the same patient. These RTQuIC results are meaningful and quantitative, but a caveat is that the assay can amplify non-infectious prion protein aggregates; therefore, the assay results are a surrogate for prion titre only. Analysis of a larger dataset that includes samples from healthy elderly individuals and/or those with conditions that might be mistaken for CJD would increase confidence in the specificity of this approach for CJD diagnosis.

Variant CJD infection has been transmitted by blood or blood product transfusion on at least five occasions, which has led to restrictions from the blood donor pool for groups deemed to be at high risk. Approaches to detect variant CJD prions in blood samples using protein misfolding cyclic amplification (PMCA) have been described in two recent papers [3, 4]. PMCA disrupts aggregates using sonication rather than shaking, requires a biological source for normal PrP rather than a recombinant protein, and uses Western blot as a readout. In one study, blood from two donors who later developed vCJD also demonstrated the presence of prions by PMCA [4]. Data from these studies provide a key step toward the validation of PMCA technology as a blood-based diagnostic test for vCJD and support its potential for detecting pre-symptomatic patients. However, the prospect of using prion detection assays to ensure the safety of blood transfusion is mitigated by several technical challenges that have yet to be overcome. Thankfully, there have been no patients diagnosed with blood-transmitted variant CJD for 10 years.

Implications for infection control and diagnosis Reports of prion transmissions, whether experimental or observational, can sometimes result in excessive media attention and misunderstandings. On occasion, notably during the BSE crisis, media attention was justified and major policy decisions needed to be taken. Our role as research scientists is to carefully discuss the findings and limitations of our results, even if not fully conclusive, with the public and policymakers. Orrú and colleagues [1] discuss their results responsibly; they emphasise that prion disease is not known to be transmitted via casual skin–skin contact, but they highlight the potential for iatrogenic transmission from this tissue. They also accept that the extreme sensitivity of the assays and methodologies used, and low RTQuIC titres in skin relative to brain, makes the interpretation of these findings in real-life infection control scenarios ambiguous. Further animal bioassay studies of skin from patients with sCJD may help to clarify the extent of infectivity.

Over 40 years ago, the demonstration of iatrogenic neurosurgical transmission of CJD and the known resistance of prions to standard decontamination methods prompted epidemiological studies of surgery and risk of CJD [5]. Most studies adopted a case–control methodology to identify patients diagnosed with CJD and retrospectively review their surgical histories compared with matched controls. The results are inconclusive, which is perhaps unsurprising in view of the inherent potential for selection bias, recall bias, and that surgery may be carried out to investigate unrecognised early symptoms of CJD [5, 6].

What about CJD diagnosis? Skin biopsy samples in the study by Orrú et al. [1] were obtained mostly from deceased patients. It will be important to ascertain the chronology; that is, whether prions accumulated as an early or late feature of the disease. An earlier study by Glatzel et al. [2] demonstrated that sCJD patients with the highest level of abnormal PrP deposition in spleen and skeletal muscle also had atypical forms and the longest disease duration. Abnormal PrP has also been detected using RTQuIC of material obtained by brushing the olfactory mucosa in sCJD [7], and by adaptation of a blood-based assay to urine [8]. However, although these findings are insightful, the most reliable method of CJD diagnosis is RTQuIC assay using cerebrospinal fluid obtained by lumbar puncture and magnetic resonance brain imaging; both of these techniques are sensitive and highly specific and are a pre-requisite in the work-up of patients suspected to have CJD to exclude other conditions [9].

Conclusions and perspectives Abnormal PrP amplification technologies are incredibly sensitive assays that provide evidence for a wider tissue distribution for prions in sCJD and rapid detection in individual patients. Whether these developments will translate into improved infection control measures is a much more complicated question, as it is very hard to find evidence for ongoing person–person transmission with surgical instruments or blood–blood product transfusion. This may be because transmissions are not currently occurring in healthcare settings, or a consequence of the challenges of epidemiological investigation of a rare disorder with potentially very long incubation periods. In this context, any new infection control measures will need to be practical and proportionate.

An increasing body of experimental and observational evidence suggests that more common neurodegenerative diseases, such as Alzheimer’s and Parkinson’s diseases, share fundamental mechanistic similarities with prion disease [10]. Whilst these similarities were proposed following animal transmission experiments and the apparent spreading of protein pathologies in the brain, recent findings raise the possibility of iatrogenic amyloid-beta cerebral amyloid angiopathy in specific circumstances that parallel the experience of acquired prion diseases [11]. This should neither be surprising nor alarming news. In this respect, recent results illustrate the potential of tools developed for prion research for the wider field of neurodegeneration and encourage their adaptation to other misfolded proteins.

Abbreviations BSE: Bovine spongiform encephalopathy

 CJD: Creutzfeldt-Jakob disease

PMCA: Protein misfolding cyclic amplification

 PrP: Prion protein

RTQuIC: Real-time quaking-induced conversion assay

sCJD: Sporadic Creutzfeldt-Jakob disease

 vCJD: Variant Creutzfeldt-Jakob disease

Declarations Funding The authors are funded by the Medical Research Council (MRC UK). Some of their work is supported by the National Institute of Health Research’s (NIHR) Biomedical Research Centre at UCL Hospitals NHS Trust. SM is a National Institute for Health Research Senior Investigator. AN is an MRC Clinical Research Training Fellow. The views expressed in this article are those of the authors and not necessarily those of the NHS, the NIHR, the MRC, or the Department of Health.

Authors’ contributions Both authors read and approved the final manuscript.

Competing interests The authors declare that they have no competing interests.

Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

References ...snip...end


Prion 2017 Conference Transmissible prions in the skin of Creutzfeldt-Jakob disease patients 

Dr. Wenguan Zou1, Dr. Christina Orru2, Jue Yuan1, Brian Appleby1, Baiya Li1, Dane Winner1, Yian Zhan1,3, Mark Rodgers1, Jason Rarick1, Robert Wyza1, Tripti Joshi1, Gongxian Wang3, Mark Cohen1, Shulin Zhang1, Bradley Groveman2, Robert Petersen1, James Ironside4, Miguel Quinones-Mateu1, Jiri Safar1, Qingzhong Kong1, Byron Caughey2 

1Case Western Reserve University, Cleveland, United States, 2Rocky Mountain Laboratories, National Institutes of Health, Hamilton, United States, 3Nanchang University, Nanchang, China, 4Universitv of Edinburgh, Edinburgh, United Kingdom 

Aims: Sporadic Creutzfeldt-Jakob disease (sCJD), the most common human prion disease, is transmissible by neuroinvasive iatrogenic routes due to abundant prion infectivity in the central nervous system (CNS). The disease-associated prion protein (PrPSc) and its infectivity have never been detected in skin from sCJD patients; however, some epidemiological studies have associated sCJD risk with skin-involved non-CNS surgeries. The aims of our study were to explore potential prion seeding activity and infectivity of skin and the feasibility of skin-based CJD diagnosis. 

Methods: Skin samples were collected at autopsy or biopsy from twenty-one sCJD, two variant CJD, and fifteen non-CJD patients and analysed by Western blotting and real-time quaking-induced conversion (RT- QulC) for PrPSc. Infectivity of skin from two sCJD patients was determined by bioassay using two lines of humanized transgenic (Tg) mice. 

Results: Western blotting demonstrated PrPSc in the skin of one of five deceased sCJD patients examined. However, the more sensitive RT-QuIC assay detected prion-seeding activity in skin from all 23 CJD decedents but not in non-CJD controls, indicating preliminary ClD diagnostic sensitivities and specificities of 100% (95% confidence intervals of 85-100%, and 78-100%, respectively). Although sCJD skins contained ~102-105-fold lower RT-QuIC seeding activity than sCJD brains, ten out of twelve mice from two Tg mouse lines inoculated with skin homogenates of two patients with two different subtypes of sCJD succumbed to prion disease within 450 days after inoculation. 

Conclusions: O sCJD patients' skin may contain both detectable prion seeding activity and transmissible prions. Our findings not only suggest a new basis for diagnostic sCJD testing, but also raise concerns about the potential for iatrogenic sCJD transmission via skin. (Funded by the CJD Foundation, the National Institute of Neurological Disorders and Stroke, the Centers for Disease Control and Prevention, as well as others) 

DISORDERS PRION 2017  DECIPHERING NEURODEGENERATIVE


*sCJD patients' skin may contain both detectable prion seeding activity and transmissible prions. 

*Our findings not only suggest a new basis for diagnostic sCJD testing, but also raise concerns about the potential for iatrogenic sCJD transmission via skin. 


Oral Session14：45～15：00O-12 Wenquan Zou

*** PrPSc in the skin of CJD patients



Accessing transmissibility and diagnostic marker of skin prions.

Kong, Qingzhong Safar, Jiri G. Zou, Wen-Quan

Case Western Reserve University, Cleveland, OH, United States

Abstract The fatal, transmissible animal and human prion diseases are characterized by the deposition in the brain of a proteinase K (PK)-resistant infectious prion protein (PrPSc), an isoform derived from the cellular protein (PrPC) through misfolding. A definitive antemortem diagnosis is virtually impossible for most patients because of the difficulty in obtaining the brain tissues by biopsy. Recently, PrPSc has been reported to be detected in the skin of experimentally or naturally scrapie-infected animals (Thomzig et al., 2007). Consistent with this finding, we have observed PK-resistant PrP in the skin of a patient with variant Creutzfeldt-Jakob disease (vCJD), an acquired form of human prion disease caused by bovine prion (Notari et al., 2010). Unexpectedly, our latest preliminary study identified two types of PK-resistant PrP molecules [with gel mobility similar to the PrPSc types 1 and 2 from the brain of sporadic CJD (sCJD)] in the fibroblast cells extracted from the skin of clinical sCJD patients and asymptomatic subjects carrying PrP mutations linked to familial CJD (fCJD). We also detected PrPSc in the skin of humanized transgenic (Tg) mice inoculated intracerebrally with a human prion. Moreover, prion infectivity has been observed in the skin of infected greater kudu (Cunningham et al., 2004) and a murine prion inoculated to mice via skin scarification can not only propagate in the skin, but also spread to the brain to cause prion disease (Wathne et al., 2012). We hypothesize that the skin of patients with prion disease harbors prion infectivity and the presence of PK-resistant PrP in the skin is a novel diagnostic marker for preclinical CJD patients. To test the hypotheses, we propose to (1) determine prion infectivity of the skin- derived fibroblasts and skin of sCJD patients and asymptomatic PrP-mutation carriers using humanized Tg mouse bioassay, (2) to pinpoint the earliest stage at which PrPSc becomes detectable in the skin of prion- infected Tg mice, and (3) to detect PrPSc in the skin of various human prion diseases, using conventional as well as highly sensitive RT-QuIC assays for both (2) and (3). If successful, our proposal may not only help prevent potential transmission of human prion diseases but also enable definitive and less intrusive antemortem diagnosis of prion diseases. Finally, knowledge generated from this study may also enhance our understanding of other neurodegenerative diseases such as Alzheimer's disease.

Public Health Relevance Currently it is unclear whether or not the skin of patients with prion diseases is infectious and, moreover, there is no alternative preclinical definitive testing or the brain biopsy in the prion diseases. The aim of our proposal is to address the issues by detection of the infectivity of patients' skin samples using animal bioassay and a new highly sensitive RT-QuIC assay. We believe that our study will not only provide insights into the pathogenesis and transmissibility of prion disease but also will develop preclinical definitive testing for prion disease.

Funding Agency Agency National Institute of Health (NIH)

Institute National Institute of Neurological Disorders and Stroke (NINDS)

Type Exploratory/Developmental Grants (R21)

Project # 1R21NS096626-01

Application # 9092119

Study Section Special Emphasis Panel (ZRG1)

Program Officer Wong, May Project Start 2016-02-01

Project End 2018-01-31

Budget Start 2016-02-01

Budget End 2017-01-31

Support Year 1

Fiscal Year 2016

Total Cost

Indirect Cost Institution Name Case Western Reserve University

Department Pathology

Type Schools of Medicine

DUNS # 077758407

City Cleveland

State OH

Country United States

Zip Code 44106



TUESDAY, MAY 10, 2016 

Accessing transmissibility and diagnostic marker of skin prions


Accumulation of Pathological Prion Protein PrPSc in the Skin of Animals with Experimental and Natural Scrapie

Achim Thomzig ,Walter Schulz-Schaeffer ,Arne Wrede,Wilhelm Wemheuer,Bertram Brenig,Christine Kratzel,Karin Lemmer,Michael Beekes Published: May 25, 2007 http://dx.doi.org/10.1371/journal.ppat.0030066

Abstract

Prion infectivity and its molecular marker, the pathological prion protein PrPSc, accumulate in the central nervous system and often also in lymphoid tissue of animals or humans affected by transmissible spongiform encephalopathies. Recently, PrPSc was found in tissues previously considered not to be invaded by prions (e.g., skeletal muscles). Here, we address the question of whether prions target the skin and show widespread PrPSc deposition in this organ in hamsters perorally or parenterally challenged with scrapie. In hamsters fed with scrapie, PrPScwas detected before the onset of symptoms, but the bulk of skin-associated PrPSc accumulated in the clinical phase. PrPSc was localized in nerve fibres within the skin but not in keratinocytes, and the deposition of PrPSc in skin showed no dependence from the route of infection and lymphotropic dissemination. The data indicated a neurally mediated centrifugal spread of prions to the skin. Furthermore, in a follow-up study, we examined sheep naturally infected with scrapie and detected PrPSc by Western blotting in skin samples from two out of five animals. Our findings point to the skin as a potential reservoir of prions, which should be further investigated in relation to disease transmission. Author Summary

Transmissible spongiform encephalopathies (TSEs), or prion diseases, are fatal neurodegenerative diseases affecting the central nervous system. According to the prion hypothesis, TSEs are caused by proteinaceous infectious particles (“prions”) that consist essentially of PrPSc, an aberrant form of the prion protein with a pathologically altered folding and/or aggregation structure. Scrapie of sheep, chronic wasting disease (CWD) of deer, bovine spongiform encephalopathy (BSE) of cattle, and variant Creutzfeldt-Jakob disease (vCJD) of humans are prominent examples of acquired prion diseases. To further pinpoint the peripheral tissues that could serve as reservoirs of prions in the mammalian body and from which these pathogens could be potentially disseminated into the environment and transmitted to other individuals, we examined the skin of hamsters perorally challenged with scrapie and of naturally infected scrapie sheep for the presence of PrPSc. We show that PrPSc can accumulate in the skin at late stages of incubation, and that the protein is located primarily in small nerve fibres within this organ. The question of whether the skin may also provide a reservoir for prions in CWD, BSE, or vCJD, and the role of the skin in relation to the natural transmission of scrapie in the field needs further investigation. Discussion In this study we have shown that the skin provides a reservoir for PrPSc, the biochemical marker of prion infectivity, in five different hamster TSE models, independently of whether the animals were challenged with scrapie via the p.o., i.c., or f.p. route, cerebral implantation of scrapie-contaminated s.w., or i.c. inoculation of a hamster-adapted BSE agent. Furthermore, PrPSc could be demonstrated for the first time in skin specimens from sheep naturally infected with scrapie, though in a limited number of sites investigated and at low amounts. In a time-course study using hamsters fed with scrapie agent, we were able to detect PrPSc in the skin before the onset of clinical symptoms, but the bulk of skin-associated PrPSc accumulated in the clinical phase of the disease. From our Western blot findings, the final concentration of PrPSc in the skin of hamsters seems to be approximately 5,000–10,000 times lower than that found in the brain. This would correspond to an infectivity titre of ~ 1 × 105 to 2 × 105 50% i.c. infective doses (ID50i.c.) per gram of skin tissue. A similar infectivity titre was previously estimated from Western blot findings for skeletal muscle tissue of clinically ill hamsters perorally challenged with 263K scrapie [23]. 


A Kiss of a Prion: New Implications for Oral Transmissibility 

The transmissibility of scrapie among sheep (intraspecies) is well recognized. It must be emphasized that horizontal transfer (from one individual to another) of scrapie is the main route of infection, because vertical transmission of disease from mother to offspring via milk or placental tissue occurs infrequently. Thus, in view of the report by Maddison et al, the oral transmissibility of prions among sheep may serve as a major route for horizontal scrapie transfer. This occurrence is plausible because sheep often lick each other. Maddison et al [10] indicate that, because of the similarities in prion tissue distribution, their implications for the oral transmission of ovine scrapie might be true for other prion diseases, such as cervid chronic wasting disease and human vCJD. If this is true for humans, a kiss of a prion may sometimes have lethal consequences.



PERSON TO PERSON TRANSMISSION OF THE TSE PRION DISEASE, never say never. as the disease mutates, it becomes more virulent in some cases, and cwd is efficiently transmitted from cervid to cervid. there are now multiple strains of CWD in cervids, as with the TSE prion disease in bovine, sheep and goats, and we now have the atypical TSE in these species, that have mutated, and some strains _have_ become more virulent. we now have younger humans dying from the TSE prion disease, with shorter incubation period, and that are much younger. human to human casual transmission of the TSE prion disease...again, never say never. ...TSS

see more here;


The occurrence of the disease in a patient who had contact with cases of familial C.J.D., but was not genetically related, has been described in Chile (Galvez et al., 1980) and in France (Brown et al., 1979b). In Chile the patient was related by marriage, but with no consanguinity, and had social contact with subsequently affected family members for 13 years before developing the disease. The contact case in France also married into a family in which C.J.D. was prevalent and had close contact with an affected member. In neither instance did the spouse of the non-familial case have the disease. The case described in this report was similarly related to affected family members and social contact had occurred for 20 years prior to developing C.J.D. If contact transmission had occurred, the minimum transmission period would be 11 years. Contact between sporadic cases has not been described and it is remarkable that possible contact transmissions have all been with familial cases. No method of transmission by casual social contact has been suggested.

***The occurrence of contact cases raises the possibility that transmission in families may be effected by an unusually virulent strain of the agent.

snip...see full text here;



TUESDAY, SEPTEMBER 13, 2016

Prion-Seeding Activity Is widely Distributed in Tissues of Sporadic Creutzfeldt-Jakob Disease Patients


TUESDAY, JUNE 20, 2017 

Prion 2017 Conference Transmissible prions in the skin of Creutzfeldt-Jakob disease patients


Sunday, February 25, 2018 

PRION ROUND TABLE CONFERENCE 2018 MAY, 22-25 A REVIEW


***Moreover, sporadic disease has never been observed in breeding colonies or primate research laboratories, most notably among hundreds of animals over several decades of study at the National Institutes of Health25, and in nearly twenty older animals continuously housed in our own facility.*** 


WEDNESDAY, MARCH 28, 2018 

USDA APHIS NOTICE: APHIS Revises Chronic Wasting Disease Program Standards March 28, 2018

Scientific opinion on chronic wasting disease (II) EFSA Panel on Biological Hazards (BIOHAZ) ZOONOSIS


FRIDAY, MARCH 30, 2018 

Docket No. APHIS-2018-0011 Chronic Wasting Disease Herd Certification Program Standards Singeltary Submission March 30, 2018


''In particular the US data do not clearly exclude the possibility of human (sporadic or familial) TSE development due to consumption of venison. The Working Group thus recognizes a potential risk to consumers if a TSE would be present in European cervids.''

Scientific opinion on chronic wasting disease (II)


EFSA Panel on Biological Hazards (BIOHAZ) Antonia Ricci Ana Allende Declan Bolton Marianne Chemaly Robert Davies Pablo Salvador Fernández Escámez ... See all authors 

First published: 17 January 2018 https://doi.org/10.2903/j.efsa.2018.5132 ;

8. Even though human TSE‐exposure risk through consumption of game from European cervids can be assumed to be minor, if at all existing, no final conclusion can be drawn due to the overall lack of scientific data. In particular the US data do not clearly exclude the possibility of human (sporadic or familial) TSE development due to consumption of venison. The Working Group thus recognizes a potential risk to consumers if a TSE would be present in European cervids. It might be prudent considering appropriate measures to reduce such a risk, e.g. excluding tissues such as CNS and lymphoid tissues from the human food chain, which would greatly reduce any potential risk for consumers. However, it is stressed that currently, no data regarding a risk of TSE infections from cervid products are available.

snip...

The tissue distribution of infectivity in CWD‐infected cervids is now known to extend beyond CNS and lymphoid tissues. While the removal of these specific tissues from the food chain would reduce human dietary exposure to infectivity, exclusion from the food chain of the whole carcass of any infected animal would be required to eliminate human dietary exposure.


zoonosis zoonotic cervid tse prion cwd to humans, preparing for the storm

***An alternative to modeling the species barrier is the cell-free conversion assay which points to CWD as the animal prion disease with the greatest zoonotic potential, after (and very much less than) BSE.116***


***> However, to date, no CWD infections have been reported in people. 

key word here is 'reported'. science has shown that CWD in humans will look like sporadic CJD. SO, how can one assume that CWD has not already transmitted to humans? they can't, and it's as simple as that. from all recorded science to date, CWD has already transmitted to humans, and it's being misdiagnosed as sporadic CJD. ...terry 

LOOKING FOR CWD IN HUMANS AS nvCJD or as an ATYPICAL CJD, LOOKING IN ALL THE WRONG PLACES $$$ 

*** These results would seem to suggest that CWD does indeed have zoonotic potential, at least as judged by the compatibility of CWD prions and their human PrPC target. Furthermore, extrapolation from this simple in vitro assay suggests that if zoonotic CWD occurred, it would most likely effect those of the PRNP codon 129-MM genotype and that the PrPres type would be similar to that found in the most common subtype of sCJD (MM1).*** 




To date there is no direct evidence that CWD has been or can be transmitted from animals to humans. 

However, initial findings from a laboratory research project funded by the Alberta Prion Research Institute (APRI) and Alberta Livestock Meat Agency (ALMA), and led by a Canadian Food Inspection Agency (CFIA) scientist indicate that CWD has been transmitted to cynomolgus macaques (the non-human primate species most closely related to humans that may be used in research), through both the intracranial and oral routes of exposure. 

Both infected brain and muscle tissues were found to transmit disease. 

Health Canada’s Health Products and Food Branch (HPFB) was asked to consider the impact of these findings on the Branch’s current position on CWD in health products and foods. 

Summary and Recommendation: 

snip...

Health Portfolio partners were recently made aware of initial findings from a research project led by a CFIA scientist that have demonstrated that cynomolgus macaques can be infected via intracranial exposure and oral gavage with CWD infected muscle. 

These findings suggest that CWD, under specific experimental conditions, has the potential to cross the human species barrier, including by enteral feeding of CWD infected muscle. 


*** WDA 2016 NEW YORK *** 

We found that CWD adapts to a new host more readily than BSE and that human PrP was unexpectedly prone to misfolding by CWD prions. 

In addition, we investigated the role of specific regions of the bovine, deer and human PrP protein in resistance to conversion by prions from another species. 

***We have concluded that the human protein has a region that confers unusual susceptibility to conversion by CWD prions. 

Student Presentations Session 2 

The species barriers and public health threat of CWD and BSE prions 

Ms. Kristen Davenport1, Dr. Davin Henderson1, Dr. Candace Mathiason1, Dr. Edward Hoover1 1Colorado State University 

Chronic wasting disease (CWD) is spreading rapidly through cervid populations in the USA. Bovine spongiform encephalopathy (BSE, mad cow disease) arose in the 1980s because cattle were fed recycled animal protein. 

These and other prion diseases are caused by abnormal folding of the normal prion protein (PrP) into a disease causing form (PrPd), which is pathogenic to nervous system cells and can cause subsequent PrP to misfold. CWD spreads among cervids very efficiently, but it has not yet infected humans. On the other hand, BSE was spread only when cattle consumed infected bovine or ovine tissue, but did infect humans and other species. 

The objective of this research is to understand the role of PrP structure in cross-species infection by CWD and BSE. To study the propensity of each species’ PrP to be induced to misfold by the presence of PrPd from verious species, we have used an in vitro system that permits detection of PrPd in real-time. 

We measured the conversion efficiency of various combinations of PrPd seeds and PrP substrate combinations. 

We observed the cross-species behavior of CWD and BSE, in addition to feline-adapted CWD and BSE. We found that CWD adapts to a new host more readily than BSE and that human PrP was unexpectedly prone to misfolding by CWD prions. In addition, we investigated the role of specific regions of the bovine, deer and human PrP protein in resistance to conversion by prions from another species. 

***We have concluded that the human protein has a region that confers unusual susceptibility to conversion by CWD prions. CWD is unique among prion diseases in its rapid spread in natural populations. BSE prions are essentially unaltered upon passage to a new species, while CWD adapts to the new species. This adaptation has consequences for surveillance of humans exposed to CWD. Wildlife Disease Risk Communication Research Contributes to Wildlife Trust Administration Exploring perceptions about chronic wasting disease risks among wildlife and agriculture professionals and stakeholders


PRION 2016 TOKYO Zoonotic Potential of CWD Prions: 

An Update 

Chronic wasting disease (CWD) is a widespread and highly transmissible prion disease in free-ranging and captive cervid species in North America. The zoonotic potential of CWD prions is a serious public health concern, but the susceptibility of human CNS and peripheral organs to CWD prions remains largely unresolved. We reported earlier that peripheral and CNS infections were detected in transgenic mice expressing human PrP129M or PrP129V. Here we will present an update on this project, including evidence for strain dependence and influence of cervid PrP polymorphisms on CWD zoonosis as well as the characteristics of experimental human CWD prions. 

PRION 2016 TOKYO In Conjunction with Asia Pacific Prion Symposium 2016 PRION 2016 Tokyo Prion 2016 


Cervid to human prion transmission 

Kong, Qingzhong Case Western Reserve University, Cleveland, OH, United States 

Abstract 

Prion disease is transmissible and invariably fatal. Chronic wasting disease (CWD) is the prion disease affecting deer, elk and moose, and it is a widespread and expanding epidemic affecting 22 US States and 2 Canadian provinces so far. 

CWD poses the most serious zoonotic prion transmission risks in North America because of huge venison consumption (>6 million deer/elk hunted and consumed annually in the USA alone), significant prion infectivity in muscles and other tissues/fluids from CWD-affected cervids, and usually high levels of individual exposure to CWD resulting from consumption of the affected animal among often just family and friends. 

However, we still do not know whether CWD prions can infect humans in the brain or peripheral tissues or whether clinical/asymptomatic CWD zoonosis has already occurred, and we have no essays to reliably detect CWD infection in humans. We hypothesize that: 

(1) The classic CWD prion strain can infect humans at low levels in the brain and peripheral lymphoid tissues; 

(2) The cervid-to-human transmission barrier is dependent on the cervid prion strain and influenced by the host (human) prion protein (PrP) primary sequence; 

(3) Reliable essays can be established to detect CWD infection in humans; and 

***(4) CWD transmission to humans has already occurred. 

We will test these hypotheses in 4 Aims using transgenic (Tg) mouse models and complementary in vitro approaches. 

Aim 1 will prove that the classical CWD strain may infect humans in brain or peripheral lymphoid tissues at low levels by conducting systemic bioassays in a set of "humanized" Tg mouse lines expressing common human PrP variants using a number of CWD isolates at varying doses and routes. Experimental "human CWD" samples will also be generated for Aim 3. 

Aim 2 will test the hypothesis that the cervid-to-human prion transmission barrier is dependent on prion strain and influenced by the host (human) PrP sequence by examining and comparing the transmission efficiency and phenotypes of several atypical/unusual CWD isolates/strains as well as a few prion strains from other species that have adapted to cervid PrP sequence, utilizing the same panel of humanized Tg mouse lines as in Aim 1. 

Aim 3 will establish reliable essays for detection and surveillance of CWD infection in humans by examining in details the clinical, pathological, biochemical and in vitro seeding properties of existing and future experimental "human CWD" samples generated from Aims 1-2 and compare them with those of common sporadic human Creutzfeldt-Jakob disease (sCJD) prions. 

Aim 4 will attempt to detect clinical CWD-affected human cases by examining a significant number of brain samples from prion-affected human subjects in the USA and Canada who have consumed venison from CWD-endemic areas utilizing the criteria and essays established in Aim 3. 

The findings from this proposal will greatly advance our understandings on the potential and characteristics of cervid prion transmission in humans, establish reliable essays for CWD zoonosis and potentially discover the first case(s) of CWD infection in humans. Public Health Relevance There are significant and increasing human exposure to cervid prions because chronic wasting disease (CWD, a widespread and highly infectious prion disease among deer and elk in North America) continues spreading and consumption of venison remains popular, but our understanding on cervid-to-human prion transmission is still very limited, raising public health concerns. 

This proposal aims to define the zoonotic risks of cervid prions and set up and apply essays to detect CWD zoonosis using mouse models and in vitro methods. The findings will greatly expand our knowledge on the potentials and characteristics of cervid prion transmission in humans, establish reliable essays for such infections and may discover the first case(s) of CWD infection in humans. 


Prion Infectivity in Fat of Deer with Chronic Wasting Disease▿ 

Brent Race#, Kimberly Meade-White#, Richard Race and Bruce Chesebro* + Author Affiliations

 In mice, prion infectivity was recently detected in fat. Since ruminant fat is consumed by humans and fed to animals, we determined infectivity titers in fat from two CWD-infected deer. Deer fat devoid of muscle contained low levels of CWD infectivity and might be a risk factor for prion infection of other species.



Prions in Skeletal Muscles of Deer with Chronic Wasting Disease 

Here bioassays in transgenic mice expressing cervid prion protein revealed the presence of infectious prions in skeletal muscles of CWD-infected deer, demonstrating that humans consuming or handling meat from CWD-infected deer are at risk to prion exposure.



Chronic Wasting Disease and Potential Transmission to Humans 

Ermias D. Belay,* Ryan A. Maddox,* Elizabeth S. Williams,† Michael W. Miller,‡ Pierluigi Gambetti,§ and Lawrence B. Schonberger*

Chronic wasting disease (CWD) of deer and elk is endemic in a tri-corner area of Colorado, Wyoming, and Nebraska, and new foci of CWD have been detected in other parts of the United States. Although detection in some areas may be related to increased surveillance, introduction of CWD due to translocation or natural migration of animals may account for some new foci of infection. Increasing spread of CWD has raised concerns about the potential for increasing human exposure to the CWD agent. The foodborne transmission of bovine spongiform encephalopathy to humans indicates that the species barrier may not completely protect humans from animal prion diseases. Conversion of human prion protein by CWDassociated prions has been demonstrated in an in vitro cellfree experiment, but limited investigations have not identified strong evidence for CWD transmission to humans. More epidemiologic and laboratory studies are needed to monitor the possibility of such transmissions.



*** now, let’s see what the authors said about this casual link, personal communications years ago, and then the latest on the zoonotic potential from CWD to humans from the TOKYO PRION 2016 CONFERENCE.

see where it is stated NO STRONG evidence. so, does this mean there IS casual evidence ???? “Our conclusion stating that we found no strong evidence of CWD transmission to humans”



Subject: CWD aka MAD DEER/ELK TO HUMANS ???

Date: September 30, 2002 at 7:06 am PST

From: "Belay, Ermias"

To: Cc: "Race, Richard (NIH)" ; ; "Belay, Ermias"

Sent: Monday, September 30, 2002 9:22 AM

Subject: RE: TO CDC AND NIH - PUB MED- 3 MORE DEATHS - CWD - YOUNG HUNTERS

Dear Sir/Madam,

In the Archives of Neurology you quoted (the abstract of which was attached to your email), we did not say CWD in humans will present like variant CJD. That assumption would be wrong. I encourage you to read the whole article and call me if you have questions or need more clarification (phone: 404-639-3091). Also, we do not claim that "no-one has ever been infected with prion disease from eating venison." Our conclusion stating that we found no strong evidence of CWD transmission to humans in the article you quoted or in any other forum is limited to the patients we investigated.

Ermias Belay, M.D. Centers for Disease Control and Prevention

-----Original Message-----

From: Sent: Sunday, September 29, 2002 10:15 AM


Subject: TO CDC AND NIH - PUB MED- 3 MORE DEATHS - CWD - YOUNG HUNTERS

Sunday, November 10, 2002 6:26 PM ......snip........end..............TSS

Thursday, April 03, 2008

A prion disease of cervids: Chronic wasting disease 2008 1: Vet Res. 2008 Apr 3;39(4):41 A prion disease of cervids: Chronic wasting disease Sigurdson CJ.

snip...

*** twenty-seven CJD patients who regularly consumed venison were reported to the Surveillance Center***,

snip... full text ;



 I urge everyone to watch this video closely...terry 

*** you can see video here and interview with Jeff's Mom, and scientist telling you to test everything and potential risk factors for humans ***



Transmission Studies

Mule deer transmissions of CWD were by intracerebral inoculation and compared with natural cases {the following was written but with a single line marked through it ''first passage (by this route)}...TSS

resulted in a more rapidly progressive clinical disease with repeated episodes of synocopy ending in coma. One control animal became affected, it is believed through contamination of inoculum (?saline). Further CWD transmissions were carried out by Dick Marsh into ferret, mink and squirrel monkey. Transmission occurred in ALL of these species with the shortest incubation period in the ferret.

snip...



Transmissible Spongiform Encephalopathies

Spongiform Encephalopathy in Captive Wild ZOO BSE INQUIRY


*** The potential impact of prion diseases on human health was greatly magnified by the recognition that interspecies transfer of BSE to humans by beef ingestion resulted in vCJD. While changes in animal feed constituents and slaughter practices appear to have curtailed vCJD, there is concern that CWD of free-ranging deer and elk in the U.S. might also cross the species barrier. Thus, consuming venison could be a source of human prion disease. Whether BSE and CWD represent interspecies scrapie transfer or are newly arisen prion diseases is unknown. Therefore, the possibility of transmission of prion disease through other food animals cannot be ruled out. There is evidence that vCJD can be transmitted through blood transfusion. There is likely a pool of unknown size of asymptomatic individuals infected with vCJD, and there may be asymptomatic individuals infected with the CWD equivalent. These circumstances represent a potential threat to blood, blood products, and plasma supplies. 



BSE INQUIRY

CJD9/10022

October 1994

Mr R.N. Elmhirst Chairman British Deer Farmers Association Holly Lodge Spencers Lane 

BerksWell Coventry CV7 7BZ

Dear Mr Elmhirst,

CREUTZFELDT-JAKOB DISEASE (CJD) SURVEILLANCE UNIT REPORT

Thank you for your recent letter concerning the publication of the third annual report from the CJD Surveillance Unit. I am sorry that you are dissatisfied with the way in which this report was published.

The Surveillance Unit is a completely independant outside body and the Department of Health is committed to publishing their reports as soon as they become available. In the circumstances it is not the practice to circulate the report for comment since the findings of the report would not be amended. In future we can ensure that the British Deer Farmers Association receives a copy of the report in advance of publication.

The Chief Medical Officer has undertaken to keep the public fully informed of the results of any research in respect of CJD. This report was entirely the work of the unit and was produced completely independantly of the the Department.

The statistical results reqarding the consumption of venison was put into perspective in the body of the report and was not mentioned at all in the press release. Media attention regarding this report was low key but gave a realistic presentation of the statistical findings of the Unit. This approach to publication was successful in that consumption of venison was highlighted only once by the media ie. in the News at one television proqramme.

I believe that a further statement about the report, or indeed statistical links between CJD and consumption of venison, would increase, and quite possibly give damaging credence, to the whole issue. From the low key media reports of which I am aware it seems unlikely that venison consumption will suffer adversely, if at all.



*** The association between venison eating and risk of CJD shows similar pattern, with regular venison eating associated with a 9 FOLD INCREASE IN RISK OF CJD (p = 0.04). ***

*** The association between venison eating and risk of CJD shows similar pattern, with regular venison eating associated with a 9 FOLD INCREASE IN RISK OF CJD (p = 0.04). ***

*** The association between venison eating and risk of CJD shows similar pattern, with regular venison eating associated with a 9 FOLD INCREASE IN RISK OF CJD (p = 0.04). ***

There is some evidence that risk of CJD INCREASES WITH INCREASING FREQUENCY OF LAMB EATING (p = 0.02).

The evidence for such an association between beef eating and CJD is weaker (p = 0.14). When only controls for whom a relative was interviewed are included, this evidence becomes a little STRONGER (p = 0.08).

snip...

It was found that when veal was included in the model with another exposure, the association between veal and CJD remained statistically significant (p = < 0.05 for all exposures), while the other exposures ceased to be statistically significant (p = > 0.05).

snip...

In conclusion, an analysis of dietary histories revealed statistical associations between various meats/animal products and INCREASED RISK OF CJD. When some account was taken of possible confounding, the association between VEAL EATING AND RISK OF CJD EMERGED AS THE STRONGEST OF THESE ASSOCIATIONS STATISTICALLY. ...

snip...

In the study in the USA, a range of foodstuffs were associated with an increased risk of CJD, including liver consumption which was associated with an apparent SIX-FOLD INCREASE IN THE RISK OF CJD. By comparing the data from 3 studies in relation to this particular dietary factor, the risk of liver consumption became non-significant with an odds ratio of 1.2 (PERSONAL COMMUNICATION, PROFESSOR A. HOFMAN. ERASMUS UNIVERSITY, ROTTERDAM). (???...TSS)

snip...see full report ;



TUESDAY, SEPTEMBER 12, 2017 

CDC Now Recommends Strongly consider having the deer or elk tested for CWD before you eat the meat 


SATURDAY, JANUARY 27, 2018 

CDC CHRONIC WASTING DISEASE CWD TSE PRION UPDATE REPORT USA JANUARY 2018


Subject: CDC CHRONIC WASTING DISEASE CWD TSE PRION UPDATE REPORT USA JANUARY 2018

CHRONIC WASTING DISEASE CWD TSE PRION IS THE USA AND NORTH AMERICA'S MAD COW DISEASE. 

THE USDA INC ET AL WORKED VERY HARD CONCEALING BSE TSE PRION IN CATTLE. they almost succeeded $$$

BUT CWD TSE PRION IN CERVIDS IS A DIFFERENT BEAST, THE COVER UP THERE, USDA INC COULD NOT CONTAIN.

SPORADIC CJD IS 85%+ OF ALL HUMAN TSE PRION DISEASE.

SPORADIC CJD HAS NOW BEEN LINKED TO TYPICAL AND ATYPICAL BSE, SCRAPIE, AND CWD.

SPORADIC/SPONTANEOUS TSE HAS NEVER BEEN PROVEN.

***Moreover, sporadic disease has never been observed in breeding colonies or primate research laboratories, most notably among hundreds of animals over several decades of study at the National Institutes of Health25, and in nearly twenty older animals continuously housed in our own facility.***


CDC CWD TSE PRION UPDATE USA JANUARY 2018

As of January 2018, CWD in free-ranging deer, elk and/or moose has been reported in at least 22 states in the continental United States, as well as two provinces in Canada. In addition, CWD has been reported in reindeer and moose in Norway, and a small number of imported cases have been reported in South Korea. The disease has also been found in farmed deer and elk. CWD was first identified in captive deer in the late 1960s in Colorado and in wild deer in 1981. By the 1990s, it had been reported in surrounding areas in northern Colorado and southern Wyoming. Since 2000, the area known to be affected by CWD in free-ranging animals has increased to at least 22 states, including states in the Midwest, Southwest, and limited areas on the East Coast.. It is possible that CWD may also occur in other states without strong animal surveillance systems, but that cases haven’t been detected yet. Once CWD is established in an area, the risk can remain for a long time in the environment. The affected areas are likely to continue to expand. Nationwide, the overall occurrence of CWD in free-ranging deer and elk is relatively low. However, in several locations where the disease is established, infection rates may exceed 10 percent (1 in 10), and localized infection rates of more than 25 percent (1 in 4) have been reported. The infection rates among some captive deer can be much higher, with a rate of 79% (nearly 4 in 5) reported from at least one captive herd. As of January 2018, there were 186 counties in 22 states with reported CWD in free-ranging cervids. 

Chronic Wasting Disease Among Free-Ranging Cervids by County, United States, January 2018 

snip.... 


Prion 2017 Conference Abstracts CWD

 2017 PRION CONFERENCE 

First evidence of intracranial and peroral transmission of Chronic Wasting Disease (CWD) into Cynomolgus macaques: a work in progress 

Stefanie Czub1, Walter Schulz-Schaeffer2, Christiane Stahl-Hennig3, Michael Beekes4, Hermann Schaetzl5 and Dirk Motzkus6 1 

University of Calgary Faculty of Veterinary Medicine/Canadian Food Inspection Agency; 2Universitatsklinikum des Saarlandes und Medizinische Fakultat der Universitat des Saarlandes; 3 Deutsches Primaten Zentrum/Goettingen; 4 Robert-Koch-Institut Berlin; 5 University of Calgary Faculty of Veterinary Medicine; 6 presently: Boehringer Ingelheim Veterinary Research Center; previously: Deutsches Primaten Zentrum/Goettingen 

This is a progress report of a project which started in 2009. 21 cynomolgus macaques were challenged with characterized CWD material from white-tailed deer (WTD) or elk by intracerebral (ic), oral, and skin exposure routes. Additional blood transfusion experiments are supposed to assess the CWD contamination risk of human blood product. Challenge materials originated from symptomatic cervids for ic, skin scarification and partially per oral routes (WTD brain). Challenge material for feeding of muscle derived from preclinical WTD and from preclinical macaques for blood transfusion experiments. We have confirmed that the CWD challenge material contained at least two different CWD agents (brain material) as well as CWD prions in muscle-associated nerves. 

Here we present first data on a group of animals either challenged ic with steel wires or per orally and sacrificed with incubation times ranging from 4.5 to 6.9 years at postmortem. Three animals displayed signs of mild clinical disease, including anxiety, apathy, ataxia and/or tremor. In four animals wasting was observed, two of those had confirmed diabetes. All animals have variable signs of prion neuropathology in spinal cords and brains and by supersensitive IHC, reaction was detected in spinal cord segments of all animals. Protein misfolding cyclic amplification (PMCA), real-time quaking-induced conversion (RT-QuiC) and PET-blot assays to further substantiate these findings are on the way, as well as bioassays in bank voles and transgenic mice. 

At present, a total of 10 animals are sacrificed and read-outs are ongoing. Preclinical incubation of the remaining macaques covers a range from 6.4 to 7.10 years. Based on the species barrier and an incubation time of > 5 years for BSE in macaques and about 10 years for scrapie in macaques, we expected an onset of clinical disease beyond 6 years post inoculation. 

PRION 2017 DECIPHERING NEURODEGENERATIVE DISORDERS 

Subject: PRION 2017 CONFERENCE DECIPHERING NEURODEGENERATIVE DISORDERS VIDEO 

PRION 2017 CONFERENCE DECIPHERING NEURODEGENERATIVE DISORDERS 

*** PRION 2017 CONFERENCE VIDEO 



TUESDAY, JUNE 13, 2017

PRION 2017 CONFERENCE ABSTRACT 

First evidence of intracranial and peroral transmission of Chronic Wasting Disease (CWD) into Cynomolgus macaques: a work in progress


PRION CONFERENCE 2015, 2016, 2017, ON potential for CWD TSE PRION ZOONOSIS, if it has not happened already...

O.05: Transmission of prions to primates after extended silent incubation periods: Implications for BSE and scrapie risk assessment in human populations Emmanuel Comoy, Jacqueline Mikol, Valerie Durand, Sophie Luccantoni, Evelyne Correia, Nathalie Lescoutra, Capucine Dehen, and Jean-Philippe Deslys Atomic Energy Commission; Fontenay-aux-Roses, France Prion diseases (PD) are the unique neurodegenerative proteinopathies reputed to be transmissible under field conditions since decades. The transmission of Bovine Spongiform Encephalopathy (BSE) to humans evidenced that an animal PD might be zoonotic under appropriate conditions. Contrarily, in the absence of obvious (epidemiological or experimental) elements supporting a transmission or genetic predispositions, PD, like the other proteinopathies, are reputed to occur spontaneously (atpical animal prion strains, sporadic CJD summing 80% of human prion cases). Non-human primate models provided the first evidences supporting the transmissibiity of human prion strains and the zoonotic potential of BSE. Among them, cynomolgus macaques brought major information for BSE risk assessment for human health (Chen, 2014), according to their phylogenetic proximity to humans and extended lifetime. We used this model to assess the zoonotic potential of other animal PD from bovine, ovine and cervid origins even after very long silent incubation periods. 

*** We recently observed the direct transmission of a natural classical scrapie isolate to macaque after a 10-year silent incubation period, 

***with features similar to some reported for human cases of sporadic CJD, albeit requiring fourfold long incubation than BSE. Scrapie, as recently evoked in humanized mice (Cassard, 2014), 

***is the third potentially zoonotic PD (with BSE and L-type BSE), 

***thus questioning the origin of human sporadic cases. 

We will present an updated panorama of our different transmission studies and discuss the implications of such extended incubation periods on risk assessment of animal PD for human health. 

=============== 

***thus questioning the origin of human sporadic cases*** 

=============== 

***our findings suggest that possible transmission risk of H-type BSE to sheep and human. Bioassay will be required to determine whether the PMCA products are infectious to these animals. 

============== 


***Transmission data also revealed that several scrapie prions propagate in HuPrP-Tg mice with efficiency comparable to that of cattle BSE. While the efficiency of transmission at primary passage was low, subsequent passages resulted in a highly virulent prion disease in both Met129 and Val129 mice. 

***Transmission of the different scrapie isolates in these mice leads to the emergence of prion strain phenotypes that showed similar characteristics to those displayed by MM1 or VV2 sCJD prion. 

***These results demonstrate that scrapie prions have a zoonotic potential and raise new questions about the possible link between animal and human prions. 


PRION 2016 TOKYO

Saturday, April 23, 2016

SCRAPIE WS-01: Prion diseases in animals and zoonotic potential 2016

Prion. 10:S15-S21. 2016 ISSN: 1933-6896 printl 1933-690X online

Taylor & Francis

Prion 2016 Animal Prion Disease Workshop Abstracts

WS-01: Prion diseases in animals and zoonotic potential

Juan Maria Torres a, Olivier Andreoletti b, J uan-Carlos Espinosa a. Vincent Beringue c. Patricia Aguilar a,

Natalia Fernandez-Borges a. and Alba Marin-Moreno a

"Centro de Investigacion en Sanidad Animal ( CISA-INIA ). Valdeolmos, Madrid. Spain; b UMR INRA -ENVT 1225 Interactions Holes Agents Pathogenes. ENVT. Toulouse. France: "UR892. Virologie lmmunologie MolécuIaires, Jouy-en-Josas. France

Dietary exposure to bovine spongiform encephalopathy (BSE) contaminated bovine tissues is considered as the origin of variant Creutzfeldt Jakob (vCJD) disease in human. To date, BSE agent is the only recognized zoonotic prion. Despite the variety of Transmissible Spongiform Encephalopathy (TSE) agents that have been circulating for centuries in farmed ruminants there is no apparent epidemiological link between exposure to ruminant products and the occurrence of other form of TSE in human like sporadic Creutzfeldt Jakob Disease (sCJD). However, the zoonotic potential of the diversity of circulating TSE agents has never been systematically assessed. The major issue in experimental assessment of TSEs zoonotic potential lies in the modeling of the ‘species barrier‘, the biological phenomenon that limits TSE agents’ propagation from a species to another. In the last decade, mice genetically engineered to express normal forms of the human prion protein has proved essential in studying human prions pathogenesis and modeling the capacity of TSEs to cross the human species barrier.

To assess the zoonotic potential of prions circulating in farmed ruminants, we study their transmission ability in transgenic mice expressing human PrPC (HuPrP-Tg). Two lines of mice expressing different forms of the human PrPC (129Met or 129Val) are used to determine the role of the Met129Val dimorphism in susceptibility/resistance to the different agents.

These transmission experiments confirm the ability of BSE prions to propagate in 129M- HuPrP-Tg mice and demonstrate that Met129 homozygotes may be susceptible to BSE in sheep or goat to a greater degree than the BSE agent in cattle and that these agents can convey molecular properties and neuropathological indistinguishable from vCJD. However homozygous 129V mice are resistant to all tested BSE derived prions independently of the originating species suggesting a higher transmission barrier for 129V-PrP variant.

Transmission data also revealed that several scrapie prions propagate in HuPrP-Tg mice with efficiency comparable to that of cattle BSE. While the efficiency of transmission at primary passage was low, subsequent passages resulted in a highly virulent prion disease in both Met129 and Val129 mice. 

Transmission of the different scrapie isolates in these mice leads to the emergence of prion strain phenotypes that showed similar characteristics to those displayed by MM1 or VV2 sCJD prion. 

These results demonstrate that scrapie prions have a zoonotic potential and raise new questions about the possible link between animal and human prions. 


why do we not want to do TSE transmission studies on chimpanzees $

5. A positive result from a chimpanzee challenged severly would likely create alarm in some circles even if the result could not be interpreted for man. I have a view that all these agents could be transmitted provided a large enough dose by appropriate routes was given and the animals kept long enough. Until the mechanisms of the species barrier are more clearly understood it might be best to retain that hypothesis.

snip...

R. BRADLEY


Title: Transmission of scrapie prions to primate after an extended silent incubation period) 

*** In complement to the recent demonstration that humanized mice are susceptible to scrapie, we report here the first observation of direct transmission of a natural classical scrapie isolate to a macaque after a 10-year incubation period. Neuropathologic examination revealed all of the features of a prion disease: spongiform change, neuronal loss, and accumulation of PrPres throughout the CNS. 

*** This observation strengthens the questioning of the harmlessness of scrapie to humans, at a time when protective measures for human and animal health are being dismantled and reduced as c-BSE is considered controlled and being eradicated. 

*** Our results underscore the importance of precautionary and protective measures and the necessity for long-term experimental transmission studies to assess the zoonotic potential of other animal prion strains. 


TUESDAY, DECEMBER 12, 2017 

Creutzfeldt Jakob Disease CJD National Prion Disease Pathology Surveillance Center Cases Examined to December 14, 2017

http://creutzfeldt-jakob-disease.blogspot.com/2017/12/creutzfeldt-jakob-disease-cjd-national.html

Tuesday, December 12, 2017 

Neuropathology of iatrogenic Creutzfeldt–Jakob disease and immunoassay of French cadaver-sourced growth hormone batches suggest possible transmission of tauopathy and long incubation periods for the transmission of Abeta pathology

http://tauopathies..blogspot.com/2017/12/neuropathology-of-iatrogenic.html

MONDAY, OCTOBER 02, 2017 

Creutzfeldt Jakob Disease United States of America USA and United Kingdom UK Increasing and Zoonotic Pontential From Different Species

http://creutzfeldt-jakob-disease.blogspot.com/2017/10/creutzfeldt-jakob-disease-united-states.html

THURSDAY, AUGUST 17, 2017 

*** Monitoring the occurrence of emerging forms of Creutzfeldt-Jakob disease in the United States revisited 2017

Singeltary et al

http://creutzfeldt-jakob-disease.blogspot.com/2017/08/monitoring-occurrence-of-emerging-forms.html

Tuesday, March 20, 2018 

Variably protease-sensitive prionopathy (VPSPr), sporadic creutzfeldt jakob disease sCJD, the same disease, what if?



Re-Evidence for human transmission of amyloid-β pathology and cerebral amyloid angiopathy 

>>> The only tenable public line will be that "more research is required’’ <<< 

>>> possibility on a transmissible prion remains open<<< 

O.K., so it’s about 23 years later, so somebody please tell me, when is "more research is required’’ enough time for evaluation ? 

Re-Evidence for human transmission of amyloid-β pathology and cerebral amyloid angiopathy 

Nature 525, 247?250 (10 September 2015) doi:10.1038/nature15369 Received 26 April 2015 Accepted 14 August 2015 Published online 09 September 2015 Updated online 11 September 2015 Erratum (October, 2015) 

snip...see full Singeltary Nature comment here; 

Alzheimer's disease

let's not forget the elephant in the room. curing Alzheimer's would be a great and wonderful thing, but for starters, why not start with the obvious, lets prove the cause or causes, and then start to stop that. think iatrogenic, friendly fire, or the pass it forward mode of transmission. think medical, surgical, dental, tissue, blood, related transmission. think transmissible spongiform encephalopathy aka tse prion disease aka mad cow type disease... 

Commentary: Evidence for human transmission of amyloid-β pathology and cerebral amyloid angiopathy





Self-Propagative Replication of Ab Oligomers Suggests Potential Transmissibility in Alzheimer Disease 

*** Singeltary comment PLoS *** 

Alzheimer’s disease and Transmissible Spongiform Encephalopathy prion disease, Iatrogenic, what if ? 

Posted by flounder on 05 Nov 2014 at 21:27 GMT 


IN CONFIDENCE

5 NOVEMBER 1992

TRANSMISSION OF ALZHEIMER TYPE PLAQUES TO PRIMATES

[9. Whilst this matter is not at the moment directly concerned with the iatrogenic CJD cases from hgH, there remains a possibility of litigation here, and this presents an added complication. 

There are also results to be made available shortly 

(1) concerning a farmer with CJD who had BSE animals, 

(2) on the possible transmissibility of Alzheimer’s and 

(3) a CMO letter on prevention of iatrogenic CJD transmission in neurosurgery, all of which will serve to increase media interest.]




snip...see full Singeltary Nature comment here; 

re-Evidence for human transmission of amyloid-? pathology and cerebral amyloid angiopathy Nature 525, 247?250 (10 September 2015) doi:10.1038/nature15369 Received 26 April 2015 Accepted 14 August 2015 Published online 09 September 2015 Updated online 11 September 2015 Erratum (October, 2015)


I would kindly like to comment on the Nature Paper, the Lancet reply, and the newspaper articles.

First, I applaud Nature, the Scientist and Authors of the Nature paper, for bringing this important finding to the attention of the public domain, and the media for printing said findings.

Secondly, it seems once again, politics is getting in the way possibly of more important Transmissible Spongiform Encephalopathy TSE Prion scientific findings. findings that could have great implications for human health, and great implications for the medical surgical arena. but apparently, the government peer review process, of the peer review science, tries to intervene again to water down said disturbing findings.

where have we all heard this before? it's been well documented via the BSE Inquiry. have they not learned a lesson from the last time?

we have seen this time and time again in England (and other Country's) with the BSE mad cow TSE Prion debacle.

That 'anonymous' Lancet editorial was disgraceful. The editor, Dick Horton is not a scientist.

The pituitary cadavers were very likely elderly and among them some were on their way to CJD or Alzheimer's. Not a bit unusual. Then the recipients, who got pooled extracts injected from thousands of cadavers, were 100% certain to have been injected with both seeds. No surprise that they got both diseases going after thirty year incubations.

That the UK has a "system in place to assist science journalists" to squash embargoed science reports they find 'alarming' is pathetic.

Sounds like the journalists had it right in the first place: 'Alzheimer's may be a transmissible infection? in The Independent to 'You can catch Alzheimer's' in The Daily Mirror or 'Alzheimer's bombshell' in The Daily Express

if not for the journalist, the layperson would not know about these important findings.

where would we be today with sound science, from where we were 30 years ago, if not for the cloak of secrecy and save the industry at all cost mentality?

when you have a peer review system for science, from which a government constantly circumvents, then you have a problem with science, and humans die.

to date, as far as documented body bag count, with all TSE prion named to date, that count is still relatively low (one was too many in my case, Mom hvCJD), however that changes drastically once the TSE Prion link is made with Alzheimer's, the price of poker goes up drastically.

so, who makes that final decision, and how many more decades do we have to wait?

the iatrogenic mode of transmission of TSE prion, the many routes there from, load factor, threshold from said load factor to sub-clinical disease, to clinical disease, to death, much time is there to spread a TSE Prion to anywhere, but whom, by whom, and when, do we make that final decision to do something about it globally? how many documented body bags does it take? how many more decades do we wait? how many names can we make up for one disease, TSE prion?

Professor Collinge et al, and others, have had troubles in the past with the Government meddling in scientific findings, that might in some way involve industry, never mind human and or animal health.

FOR any government to continue to circumvent science for monetary gain, fear factor, or any reason, shame, shame on you.

in my opinion, it's one of the reasons we are at where we are at to date, with regards to the TSE Prion disease science i.e. money, industry, politics, then comes science, in that order.

greed, corporate, lobbyist there from, and government, must be removed from the peer review process of sound science, it's bad enough having them in the pharmaceutical aspect of healthcare policy making, in my opinion.

my mother died from confirmed hvCJD, and her brother (my uncle) Alzheimer's of some type (no autopsy?). just made a promise, never forget, and never let them forget, before I do.

I kindly wish to remind the public of the past, and a possible future we all hopes never happens again. ...



2012

Alzheimer’s disease and Transmissible Spongiform Encephalopathy prion disease, Iatrogenic, what if ?

Background

Alzheimer’s disease and Transmissible Spongiform Encephalopathy disease have both been around a long time, and was discovered in or around the same time frame, early 1900’s. Both diseases are incurable and debilitating brain disease, that are in the end, 100% fatal, with the incubation/clinical period of the Alzheimer’s disease being longer (most of the time) than the TSE prion disease. Symptoms are very similar, and pathology is very similar.

Methods

Through years of research, as a layperson, of peer review journals, transmission studies, and observations of loved ones and friends that have died from both Alzheimer’s and the TSE prion disease i.e. Heidenhain Variant Creutzfelt Jakob Disease CJD.

Results

I propose that Alzheimer’s is a TSE disease of low dose, slow, and long incubation disease, and that Alzheimer’s is Transmissible, and is a threat to the public via the many Iatrogenic routes and sources. It was said long ago that the only thing that disputes this, is Alzheimer’s disease transmissibility, or the lack of. The likelihood of many victims of Alzheimer’s disease from the many different Iatrogenic routes and modes of transmission as with the TSE prion disease.

Conclusions

There should be a Global Congressional Science round table event set up immediately to address these concerns from the many potential routes and sources of the TSE prion disease, including Alzheimer’s disease, and a emergency global doctrine put into effect to help combat the spread of Alzheimer’s disease via the medical, surgical, dental, tissue, and blood arena’s. All human and animal TSE prion disease, including Alzheimer’s should be made reportable in every state, and Internationally, WITH NO age restrictions. Until a proven method of decontamination and autoclaving is proven, and put forth in use universally, in all hospitals and medical, surgical arena’s, or the TSE prion agent will continue to spread. IF we wait until science and corporate politicians wait until politics lets science _prove_ this once and for all, and set forth regulations there from, we will all be exposed to the TSE Prion agents, if that has not happened already.

end...tss

Alzheimer’s disease and Transmissible Spongiform Encephalopathy prion disease, Iatrogenic, what if ?

source references ...end...tss 

Hello Nicole,

by all means, please do use my poster. but I thought this was already taken care of, and I could not attend for my poster presentation, therefore, it was not going to be presented. I have some health issues and could not make the trip.

please see old correspondence below...

From: Nicole Sanders Sent: Tuesday, April 10, 2012 5:37 PM To: Terry S. Singeltary Sr. Subject: RE: re-submission

Dear Terry,

The decline of proposal number 30756 is registered in the system. Thank you for your consideration.

Best Regards,

Nicole

Nicole Sanders

Senior Specialist, Membership & Conference Programming

______________________________________


From: xxxx 

To: Terry Singeltary 

Sent: Saturday, December 05, 2009 9:09 AM 

Subject: 14th ICID - abstract accepted for 'International Scientific Exchange'

Your preliminary abstract number: 670

Dear Mr. Singeltary,

On behalf of the Scientific Committee, I am pleased to inform you that your abstract

'Transmissible Spongiform encephalopathy (TSE) animal and human TSE in North America update October 2009'

WAS accepted for inclusion in the INTERNATIONAL SCIENTIFIC EXCHANGE (ISE) section of the 14th International Congress on Infectious Diseases. Accordingly, your abstract will be included in the "Intl. Scientific Exchange abstract CD-rom" of the Congress which will be distributed to all participants.

Abstracts accepted for INTERNATIONAL SCIENTIFIC EXCHANGE are NOT PRESENTED in the oral OR poster sessions.

Your abstract below was accepted for: INTERNATIONAL SCIENTIFIC EXCHANGE

#0670: Transmissible Spongiform encephalopathy (TSE) animal and human TSE in North America update October 2009

Author: T. Singeltary; Bacliff, TX/US

Topic: Emerging Infectious Diseases Preferred type of presentation: International Scientific Exchange

This abstract has been ACCEPTED.

#0670: Transmissible Spongiform encephalopathy (TSE) animal and human TSE in North America update October 2009

Authors: T. Singeltary; Bacliff, TX/US

Title: Transmissible Spongiform encephalopathy (TSE) animal and human TSE in North America update October 2009

Body: 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.

Keywords: Transmissible Spongiform Encephalopathy Creutzfeldt Jakob Disease Prion

page 114 ;

http://ww2.isid.org/Downloads/14th_ICID_ISE_Abstracts.pdf

http://www.isid.org/14th_icid/

http://www.isid.org/publications/ICID_Archive.shtml

http://ww2.isid.org/Downloads/IMED2009_AbstrAuth.pdf
Diagnosis and Reporting of Creutzfeldt-Jakob Disease 

Singeltary, Sr et al. JAMA.2001; 285: 733-734. Vol. 285 No. 6, February 14, 2001 JAMA Diagnosis and Reporting of Creutzfeldt-Jakob Disease 

To the Editor: 

In their Research Letter, Dr Gibbons and colleagues1 reported that the annual US death rate due to Creutzfeldt-Jakob disease (CJD) has been stable since 1985. These estimates, however, are based only on reported cases, and do not include misdiagnosed or preclinical cases. It seems to me that misdiagnosis alone would drastically change these figures. An unknown number of persons with a diagnosis of Alzheimer disease in fact may have CJD, although only a small number of these patients receive the postmortem examination necessary to make this diagnosis. Furthermore, only a few states have made CJD reportable. Human and animal transmissible spongiform encephalopathies should be reportable nationwide and internationally. 

Terry S. Singeltary, Sr Bacliff, Tex 

1. Gibbons RV, Holman RC, Belay ED, Schonberger LB. Creutzfeldt-Jakob disease in the United States: 1979-1998. JAMA. 2000;284:2322-2323. 


Tracking spongiform encephalopathies in North America

Xavier Bosch

Published: August 2003


Summary;

“My name is Terry S Singeltary Sr, and I live in Bacliff, Texas. I lost my mom to hvCJD (Heidenhain variant CJD) and have been searching for answers ever since. What I have found is that we have not been told the truth. CWD in deer and elk is a small portion of a much bigger problem.”

49-year-old Singeltary is one of a number of people who have remained largely unsatisfied after being told that a close relative died from a rapidly progressive dementia compatible with spontaneous Creutzfeldt-Jakob disease (CJD). So he decided to gather hundreds of documents on transmissible spongiform encephalopathies (TSE) and realised that if Britons could get variant CJD from bovine spongiform encephalopathy (BSE), Americans might get a similar disorder from chronic wasting disease (CWD) the relative of mad cow disease seen among deer and elk in the USA. Although his feverish search did not lead him to the smoking gun linking CWD to a similar disease in North American people, it did uncover a largely disappointing situation.

Singeltary was greatly demoralised at the few attempts to monitor the occurrence of CJD and CWD in the USA. Only a few states have made CJD reportable. Human and animal TSEs should be reportable nationwide and internationally, he complained in a letter to the Journal of the American Medical Association (JAMA 2003; 285: 733). "I hope that the CDC does not continue to expect us to still believe that the 85% plus of all CJD cases which are sporadic are all spontaneous, without route or source."

Until recently, CWD was thought to be confined to the wild in a small region in Colorado. But since early 2002, it has been reported in other areas, including Wisconsin, South Dakota, and the Canadian province of Saskatchewan. Indeed, the occurrence of CWD in states that were not endemic previously increased concern about a widespread outbreak and possible transmission to people and cattle.

To date, experimental studies have proven that the CWD agent can be transmitted to cattle by intracerebral inoculation and that it can cross the mucous membranes of the digestive tract to initiate infection in lymphoid tissue before invasion of the central nervous system. Yet the plausibility of CWD spreading to people has remained elusive.

Part of the problem seems to stem from the US surveillance system. CJD is only reported in those areas known to be endemic foci of CWD. Moreover, US authorities have been criticised for not having performed enough prionic tests in farm deer and elk.

Although in November last year the US Food and Drug Administration issued a directive to state public-health and agriculture officials prohibiting material from CWD-positive animals from being used as an ingredient in feed for any animal species, epidemiological control and research in the USA has been quite different from the situation in the UK and Europe regarding BSE.

"Getting data on TSEs in the USA from the government is like pulling teeth", Singeltary argues. "You get it when they want you to have it, and only what they want you to have."

Norman Foster, director of the Cognitive Disorders Clinic at the University of Michigan (Ann Arbor, MI, USA), says that "current surveillance of prion disease in people in the USA is inadequate to detect whether CWD is occurring in human beings"; adding that, "the cases that we know about are reassuring, because they do not suggest the appearance of a new variant of CJD in the USA or atypical features in patients that might be exposed to CWD. However, until we establish a system that identifies and analyses a high proportion of suspected prion disease cases we will not know for sure". The USA should develop a system modelled on that established in the UK, he points out.

Ali Samii, a neurologist at Seattle VA Medical Center who recently reported the cases of three hunters "two of whom were friends" who died from pathologically confirmed CJD, says that "at present there are insufficient data to claim transmission of CWD into humans"; adding that "[only] by asking [the questions of venison consumption and deer/elk hunting] in every case can we collect suspect cases and look into the plausibility of transmission further". Samii argues that by making both doctors and hunters more aware of the possibility of prions spreading through eating venison, doctors treating hunters with dementia can consider a possible prion disease, and doctors treating CJD patients will know to ask whether they ate venison.

CDC spokesman Ermias Belay says that the CDC "will not be investigating the [Samii] cases because there is no evidence that the men ate CWD-infected meat". He notes that although "the likelihood of CWD jumping the species barrier to infect humans cannot be ruled out 100%" and that "[we] cannot be 100% sure that CWD does not exist in humans& the data seeking evidence of CWD transmission to humans have been very limited". 



26 March 2003 

Terry S. Singeltary, retired (medically) CJD WATCH 

I lost my mother to hvCJD (Heidenhain Variant CJD). I would like to comment on the CDC's attempts to monitor the occurrence of emerging forms of CJD. Asante, Collinge et al [1] have reported that BSE transmission to the 129-methionine genotype can lead to an alternate phenotype that is indistinguishable from type 2 PrPSc, the commonest sporadic CJD. However, CJD and all human TSEs are not reportable nationally. CJD and all human TSEs must be made reportable in every state and internationally. I hope that the CDC does not continue to expect us to still believe that the 85%+ of all CJD cases which are sporadic are all spontaneous, without route/source. We have many TSEs in the USA in both animal and man. CWD in deer/elk is spreading rapidly and CWD does transmit to mink, ferret, cattle, and squirrel monkey by intracerebral inoculation. With the known incubation periods in other TSEs, oral transmission studies of CWD may take much longer. Every victim/family of CJD/TSEs should be asked about route and source of this agent. To prolong this will only spread the agent and needlessly expose others. In light of the findings of Asante and Collinge et al, there should be drastic measures to safeguard the medical and surgical arena from sporadic CJDs and all human TSEs. I only ponder how many sporadic CJDs in the USA are type 2 PrPSc? 


2001 FDA CJD TSE Prion Singeltary Submission 


*** U.S.A. 50 STATE BSE MAD COW CONFERENCE CALL Jan. 9, 2001 


2 January 2000 British Medical Journal U.S. 

Scientist should be concerned with a CJD epidemic in the U.S., as well 


15 November 1999 British Medical Journal hvCJD in the USA * BSE in U.S. 


DECEMBER 14, 2017, 20 YEARS POST DOD MOM HEIDENHAIN VARIANT CREUTZFELDT JAKOB DISEASE HVCJD DECEMBER 14, 1997, JUST MADE A PROMISE TO MOM, AND YOU DON'T BREAK PROMISES WITH YOUR MOM, NEVER FORGET, AND NEVER LET THEM FORGET...

wasted days and wasted nights...Freddy Fender

TERRY S. SINGELTARY SR.

Terry S. Singeltary Sr. Bacliff, Texas USA 77518 <flounder9@verizon.net>

posted by Terry S. Singeltary Sr. at 1:52 PM