AN EPIDEMIOLOGIC CRITIQUE OF CREUTZFELDT-JAKOB DISEASE Vol. 2, 1980 Paul Brown vs Zohreh Davanipour and Scrapie

EPIDEMIOLOGIC REVIEWS


Copyright © 1980

by The Johns Hopkins University School of Hygiene and Public Health All rights reserved Vol. 2, 1980 Printed in U.S.A.



AN EPIDEMIOLOGIC CRITIQUE OF CREUTZFELDT-JAKOB DISEASE



PAUL BROWN



THE FACTS



"Give me your evidence" said the King; "and don't be nervous, or I'll have you executed on the spot." —Alice's Adventures in Wonderland



Creutzfeldt-Jakob disease (CJD) is a subacute degeneration of the central nervous system occurring most often in people of late middle age. Although by no means a stereotyped illness, it typically evolves as a progressive dementia with associated cerebellar or visual abnormalities and, later, pyramidal and extra-pyramidal signs with myoclonus or other abnormal movements (1, 2). The electroencephalogram may show characteristic bursts of high amplitude slow waves at a frequency of one to two cycles per second (3). Death usually occurs within six months of onset, and neuropathologic examination reveals a diffuse but uneven distribution of neuronal loss, gliosis, and spongiosis (4).



Demonstration of its transmissibility in 1968 (5) dislocated traditional concepts of human infectious disease (table 1), and a surge of new studies has shown the causative agent to be a membrane-associated, "unconventional virus" of very small size (6, 7), with unusual resistance to physical and chemical means of inactivation, including ionizing and ultraviolet irradiation (6, and C. J. Gibbs, Jr., et al., unpublished data, 1974), heat (7), formaldehyde (8), and chlorine dioxide (9). Although the Abbreviation: Creutzfeldt-Jakob disease, CJD. 1 Laboratory of Central Nervous System Studies, Building 36, Room 5B25, National Institute of Neurological and Communicative Disorders and Stroke, National Institutes of Health, Bethesda, MD 20205. The author is grateful to Drs. Alan Dickinson, Carleton Gajdusek, and William Hadlow for their critical readings of this review.



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CJD has not occurred in anyone exposed either in the field or laboratory to mink encephalopathy virus, and in any case mink (or their pelts) are not widely enough dispersed to be of zoonotic importance to human CJD. The situation with scrapie is more interesting, since sheep or sheep products enjoy a nearly worldwide distribution. Human contact with living sheep does not appear to be important, since the geographic distributions of CJD and scrapie are different, and since there is no evidence of an increased risk of CJD among high-exposure groups such as veterinarians, shepherds, and sheep farmers, even where scrapie is known to be prevalent. Contact with sheep carcasses has not been associated with an increased risk of CJD among slaughterhouse workers or butchers, including those who remove brains from the severed heads.



Contact with sheep tissues at the consumer level is more difficult to appraise. It is certainly true that millions of people in many parts of the world have come in contact with lamb, both in its handling and eating, and that lamb chops may contain sections of spinal cord, which in clinically ill animals regularly reach to fairly high virus titer levels. It is equally true that millions of people have come in contact with the serosal surface of sheep intestine in the form of surgical sutures, stringed instruments, sports rackets, sausage casings, and even certain brands of condoms. And it is also true that a much smaller but still significant population at least occasionally eats sheep brain or visceral tissues, either as individual organs or in mixtures like black puddings, or is exposed to omental fat in tallow and soap and to wool oils in lanolin creams and lotions. Ample occasion would thus appear to exist for human contamination by scrapie virus.



Consumer exposure to scrapie as a source of CJD must nevertheless be examined in light of the actual potential for virus to be present in these various products. Sheep bred for commercial purposes are almost invariably less than 15 months old when slaughtered, an age when, in all but the most exceptional animals, scrapie virus has not yet invaded the ce tral nervous system. Thus, brain and spinal cord sections in chops would not appear to pose a problem. Lamb meat is an even more dubious candidate, since in scores of attempts, virus has never been detected in sheep muscle, and only once from the muscle of an experimentally infected adult goat (84). Visceral tissues are more likely sources of contamination, as they contain virus from an early age in affected sheep, and continue to be infective in older sheep which furnish the intestinal tissue used in sausage casings. Skin has not been found infective in the only study (85) in which it has been examined, and information about the presence of virus in wool oils is not available.



130 PAUL BROWN



The chances of isolating virus from any of these various products, even assuming they were infective in the living animal, after processing or cooking, as they are actually used in the home, would be further reduced. Although there is nothing incompatible about a rare disease being produced by a rare exposure to its causative agent, the crucial assumption is that CJD represents scrapie in humans, and it is bothersome that CJD does not occur in higher than expected frequency in groups highly exposed to scrapie virus, including laboratory workers, among whom no case of CJD has ever been seen.



Summarizing the evidence relevant to horizontal transmission of CJD, we can say that the oral route of infection appears to operate in all three of the other spongiform encephalopathies—most convincingly in scrapie and mink encephalopathy, and possibly also in kuru—and that percutaneous infection also occurs in mink encephalopathy, through fighting, and possibly in kuru, through contamination of traumatized skin or mucosal surfaces during cannibalistic rites. Since humans neither graze, nor, with few exceptions, bite or eat their fellows, the contribution of these mechanisms to the spread of CJD appears to be limited. Apart from a few proven or highly suspicious cases of iatrogenic surgical transmission of CJD, there does not exist a single documented instance of transmission via any of the possible routes—respiratory, oral, venereal, dermatologic, or percutaneous— by which the more conventional viruses spread among humans.



One interesting characteristic of CJD that has not been sufficiently examined is its age distribution in the human population. Not only does the frequency of CJD show a regular rise through the middle decades of life, but also a sharp decline after peaking in the 65-75-year age group. Two questions require explanation: why is this frequency curve oriented around late middle age? and in particular, why is there a decreased frequency of CJD among the elderly?



Initial exposure to most if not all viruses of wide distribution occurs during the childhood or adolescent years and produces an immediate episode of disease. In some cases, however, the early illness may be followed by a different, lateappearing disease—for example, herpes zoster from the varicella-zoster virus, Kozhevnikov's encephalitis from tickborne encephalitis virus, and some cases of subacute sclerosing panencephalitis from measles virus; in progressive multifocal leukoencephalopathy, early exposure to the responsible JC virus passes as an inapparent infection. Thus there are precedents for considering the possibility of infection by CJD virus occurring during childhood or adolescence, whether from contact with a patient, a "carrier," or an environmental source, with a consequent 40—50-year incubation period before the neurologic disease becomes manifest, a schema which would account for the late appearance of disease, as well as both the rising and falling slopes of the age distribution curve.



It would also be consistent with the fact that the average age at onset of familial CJD is about 10 years earlier (age 50) than that of sporadic CJD (age 60), since it may reasonably be supposed that exposure to the virus would occur at an earlier age in a contaminated family setting than in the world at large. Evidence for age of onset as a function of age at exposure has al eady been presented for naturally occurring scrapie.



Vertical transmission remains the only other means by which the virus of CJD might move from one individual to another, and it would only apply to the minority of cases that are familial. This mechanism does not operate in mink encephalopathy or kuru, but is a possible means of spread in natural scrapie, where a strong maternal influence on the occurrence of disease is demonstrable, as is at



CREUTZFELDT-JAKOB DISEASE 131



least the occasional presence of virus in the female genital system and placenta. In familial CJD, however, the occurrence of cases follows paternal lineage as often as maternal lineage, and virus has not yet been found in genital organs. Moreover, maternal transmission has been shown not to occur in experimental CJD in guinea pigs (86), or in primates (87).



The choice here is therefore between a genetically integrated virus or a genetically transmitted susceptibility to infection by extraneous virus. Experimental scrapie documents the occurrence of virus susceptibility, whereas the observation that infectivity is not found in nuclear cell fractions does not encourage the idea of viral integration (88). However, a small number of viral nucleic acid copies would not have been detectable by the bioassay titrations employed. No evidence is yet available which would distinguish between the two alternatives in familial CJD, but whichever mechanism applies, it appears to operate in humans as an autosomal dominant.



Other more involved explanations of the spread of CJD can also be imagined, such as a rare CJD virus-integrated genome made manifest by a widely distributed "helper" virus, or the converse, the gene being common and the virus being rare, but they are bobbing speculations which float helplessly far from the anchors of evidence.



"It's a poor sort of memory that only works backwards." —Through the Looking-Glass



The reader may be pardoned for the uncomfortable feeling of having been led through a maze from which the exit remains terribly obscure, since the author has been equally bemused by the search. Like the physician who is foolish enough to have accepted the offer of a "loaded" clinical-pathologic conference, he will nevertheless not refuse the obligation to make a choice between impossible alternatives, and, after balancing the pros and cons of the evidence presented, offers the following indefensible opinion: humans are the sole natural hosts of CJD virus, which by virtue of its hardiness is widely and durably distributed in the environment. Infection usually occurs during the early years of life as an uncommon and random event, because of minimal infectious doses that gain entry from the hazards of minimal traumas, or possibly ingestions. For reasons as obscure as those determining the late appearance of measles, herpes, and papovavirus-induced neurologic illnesses, only in the rare individual does this infection conclude decades later in clinically apparent disease. Familial CJD operates on the basis of both genetic susceptibility and increased early exposure to environmental virus. Iatrogenic spread is an exceptional event that accounts for only the rare, accidental case. Scrapie virus in sheep does not cause CJD in humans.



In point of fact, it is simply not possible at this time to know how to select the right clues from among all the bits and pieces of information that bear on the problem of how CJD is acquired. The situation with CJD today can be compared to the mystery which a century ago surrounded the disease general paresis of the insane. Who was to suspect that this fatal dementia had been heralded by a painless chancre, and perhaps an evanescent rash many years before? And what if the chancre and the rash themselves went unnoticed, the treponeme were invisible, and the serologic test for syphilis did not exist?



The epidemiology of CJD cries out for an antibody, or other biologic marker, with which to locate and follow the disease, and the discovery of such a tool would constitute the single most important advance in our understanding of this frustrating disease. The recent demonstrations that brain tissue suspensions



132 PAUL BROWN



from a majority of CJD patients induce cellular fusion (89) and that serum from CJD patients contains autoantibodies to neurofibrils of cultivated neurons (90) are exciting new approaches to this problem, but are not yet sufficiently practical or specific to be of epidemiologic value.



Certain aspects of the disease could be clarified by additional work on its pathogenesis. Using as a model natural scrapie in sheep, a series of biopsies of intestinal lymph nodes in individual sheep over a period of time is technically feasible, and could precisely define the length of incubation period, particularly in older animals that do not show clinical illness until late in their natural lifespan, analogous to the human situation in CJD. In our laboratory, continued study of primates and guinea pigs after peripheral inoculations of minimal infectious doses of CJD virus should be helpful in providing a better idea of the infection rate and length of incubation period that might be expected to occur under similar circumstances in the human disease (experiments in progress include many animals under test less than two years, as well as a number of animals that remain well three or more years after inoculation, that may yet develop disease). In particular, the new model of orally transmitted CJD in the squirrel monkey should now be the subject of a complete pathogenetic study.



In humans and in animals infected experimentally with CJD, attempts to isolate virus from secretions, excretions, and external surfaces should be pursued, both from the clinical, and especially (in animals) the preclinical stages of disease, since knowledge of how the virus could spread would greatly facilitate study of how it does spread. In the same way, a systematic study of the viability of CJD virus outside the body, in experiments which simulate a variety of environmental conditions, would also have practical importance for theories of disease transmission.



Epidemiologic studies of the survey type have now established a descriptive base which should permit much more meaningful attempts at finding possible connections between past and present patients. Particular attention to geographically isolated cases of CJD may, in a setting of limited possibilities for infection, yield an otherwise obscured clue, and intensive genetic and epidemiologic study of CJD families could eventually unravel the ties, if any, between heritable and environmental factors in the acquisition of disease. Systematic transmission attempts from postmortem brain biopsies or autopsies of the patient population in mental and geriatric institutions could clarify the nagging doubt about the existence of unsuspected atypical or even silent forms of CJD virus infection. Continued surveillance of groups at high risk of exposure to scrapie should eventually resolve the scrapie-CJD hypothesis. Further search for environmental or animal reservoirs of CJD virus is badly needed, but will be a very expensive venture to undertake without some clue to limit the field of choice, and that choice not only already includes several susceptible rodents, but could also comprise "resistant" species as asymptomatic virus carriers, about which nothing is known.



The characteristics of rarity, randomness, long incubation period, and the absence of detectable antigenicity, make of CJD a formidable epidemiologic mystery. As with all high quality mysteries, the abundance of clues may actually obscure the solution; however, there is ample opportunity for the study of specific questions, and, in time, the right answers will be remembered.



REFERENCES



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http://epirev.oxfordjournals.org/content/2/1/113.long



RE: "AN EPIDEMIOLOGIC CRITIQUE OF CREUTZFELDT-JAKOB DISEASE"



A critical assessment of a zoonotic origin of Creutzfeldt-Jakob disease (CJD), such as scrapied sheep, was published recently in Epidemiologic Reviews by Paul Brown (1). He concluded that available evidence did not support such an origin. OF CREUTZFELDT-JAKOB DISEASE" As evidence against the zoonotic hypothesis, he offered several observations which we believe allow for alternative interpretations:



Brown stated that groups with increased exposure to sheep, e.g., veterinar 146 LETTERS TO THE EDITOR ians, butchers, slaughterhouse workers and farmers have not been "overrepresented among CJD patients." Therefore, he concluded that contact with sheep appears unimportant in causing CJD. However, his conclusion was based on occupational history available on only 308 out of 1435 cases ascertained by Masters et al. (2). Review of data from Masters et al. showed that there were one veterinarian, seven butchers, meat packers or furriers, 24 farmers or farmers' wives, and 78 food handlers (total: 110/308 = 36 per cent). Since there were no control data and the occupational universe from which cases of Masters et al. (2) were derived is unknown, the conclusion that there was no overrepresentation of individuals in occupations involving animal (e.g., sheep) exposure is unwarranted.



A case-control study directed at determining the occupation of CJD patients and matched controls might settle the issue. One such case-control study in the United States was published by Bobowick et al. (3). It was based on 38 patients and gave no details but concluded that there was "no occupational clustering in any one category." More case-control data are needed before concluding that there is, in fact, no increased incidence of CJD among certain occupational groups.



Brown pointed out that large numbers of people in different parts of the world have come into contact with sheep and lambs. If scrapie in sheep is the source of CJD, he wondered why CJD was such a rare disease. However, he recognized that a low degree of contamination of sheep with scrapie might account for low rates of CJD among individuals exposed to sheep. Moreover, processing of sheep for consumption may reduce infectivity. Since genetic factors influence susceptibility to scrapie (4-6), and possibly to CJD as well (7-9), a low frequency of CJD among people exposed to sheep may reflect lack of susceptibility to the scrapie agent rather than absence of a zoonotic source of infection.



Sotelo et al. (10) demonstrated recently that antibody against an axonal fibrillary protein which was present in 59 per cent of CJD patients and 27 per cent of kuru sera was also present in 13 per cent of patients with other neurological disease and 10 per cent of normal subjects. If this test really reflects infection with CJD agent, it may mean that there is more widespread involvement of the population than is currently suspected.



A third point raised by Brown indicates that the worldwide geographic pattern of distribution of scrapie is different from the distribution of CJD. For example, in Australia, where overt scrapie has not been detected in 20 years, the incidence of CJD may be close to that of countries where scrapie is endemic (2). However, a remote exposure (20 years ago or more) and a long incubation period could explain current cases of CJD. The hypothesis that current cases reflect more remote exposure would be supported if CJD in Australia decreased in frequency over time. Unfortunately, there is no surveillance program to monitor the temporal trend of CJD in that country.



Absence of scrapie and presence of CJD in a particular country or vice versa does not necessarily disprove the zoonotic hypothesis of CJD since these diseases are not widely recognized and may be difficult to diagnose. Case ascertainment of CJD and scrapie reflects the degree of awareness and interest of physicians and veterinarians, and the quality of diagnostic facilities. Moreover, scrapie may remain subclinical beyond the age of usual marketing and slaughter of most sheep (11). Patterns of exportation and importation of sheep and their edible products in the world cannot be ignored in considering possible contact with infected sheep or their products.



According to Brown, there was no correspondence between areas where sheep are produced and areas with the highest regional frequencies of CJD in the United States (2), France (12), or Hungary (13).



LETTERS TO THE EDITOR 147



Comparison of sheep raising areas and CJD frequency would be of limited value if sheep products, possibly contaminated with scrapie agent, were not consumed where sheep were raised. Sheep may be marketed throughout a region, though they are raised in a limited area. In France, for example, the highest rates of CJD occurred within Paris while sheep are raised mainly in the provinces. If the agent is transmitted via the oral route, it is more important to determine where sheep are consumed than where they are raised. If lamb and mutton were shipped from the provinces preferentially to Paris for consumption, the same data Brown used against the zoonotic hypothesis would actually support it.



Cathala et al. (9) reported that at least three ancestors of a family with 14 cases of CJD were shepherds. Most of the family had lived in the same farming region for generations. Mayer et al. (14) noted that sheep raising is traditional in the region where a Slovakian CJD cluster occurred. One patient, a 57-year-old female raised sheep for 12 years prior to onset of CJD and admitting eating raw sheep brain (Orolin D. et al., personal communication, 1978). Lo Russo et al. (15) reported that the places of origin of seven out of eight patients with CJD coincided with the distribution of sheep raised in Central and Southern Italy. Libya has one of the highest rates of consumption of sheep and mutton per capita in the world (16), and Libyan immigrants to Israel were found to have more than 30 times the rate of CJD as immigrants to Israel from other countries (17). Thus, some available data suggest a link between CJD and sheep exposure. However, more direct data relating sheep contact and consumption in CJD patients and controls are needed.



Brown stated that the agent of scrapie has not been detected in sheep muscle. Since mainly muscle is consumed when sheep are eaten, he did not think that sheep meat was a reasonable source of the scrapie agent. However, Pattison and Millson (18) did detect the scrapie virus in the muscle of experimentally infected goats. Very few transmission and virus recovery experiments were done with sheep muscle compared with the number done with other tissues. It should be realized that sheep meat prepared for consumption also contains blood vessels, nervous and lymphatic tissues. Lamb and mutton chops may even contain spinal cord. It has been well established that lymphatic tissues of affected sheep contain scrapie virus from an early age. Even after invading the central nervous system, scrapie agent continues to exist in other tissues (19).



Recently, a neurotropic retrovirus has been identified in wild mice which is associated with a noninflammatory spongiform polioencephalopathy, like that seen in scrapied sheep (20-22). Williams and Young (23) reported an insidious, fatal disease with spongiform encephalopathic features in mule deer. The pathology was similar to that seen in the brain of scrapied sheep and CJD patients. Two outbreaks of mink encephalopathy have been traced to a common food source believed to contain sheep carcass products (24). Matthews et al. (25) reported four CJD patients each of whom kept a ferret as a pet. Goats as well as sheep are susceptible to scrapie. Thus, scrapie virus certainly has a wider host range than sheep.



It has been reported that CJD patients more often than their matched control admitted consuming hog brain (3). Goats which are susceptible to scrapie are genetically closer to cattle than they are to sheep. Cattle have not been excluded as asymptomatic hosts of the scrapie agent. Some animal hosts besides sheep and goats may constitute a reservoir for human CJD.



In Brown's review article, various mammals (goats, mice, rats, hamsters, ferrets, mink, guinea pigs, cats) in close contact with humans were listed as susceptible to experimental infection with Downloaded from aje.oxfordjournals.org by Terry Singeltary on February 10, 2011 148 LETTERS TO THE EDITOR CJD tissue. Sheep were listed as being resistant. Recently, Hadlow et al. (26) reported two goats who developed encephalopathy which was indistinguishable from scrapie 43 months after they were inoculated with brain of two definite and transmitted CJD cases. Passage of scrapie virus and development of the disease in monkeys (Compton strain), ferrets or mink altered infectivity of scrapie so that it no longer produced disease in mice (27). Therefore, failure to transmit experimentally from some sources does not necessarily imply that the agent is different or that the host cannot be infected. It simply may represent altered infectivity of the agent by passage through certain hosts.



Finally, Brown stated that there is no proof yet that CJD can be acquired by oral ingestion of the slow virus agent even though the oral route of infection is well established in scrapie (28, 29), kuru (30), and transmissible mink encephalopathy (31). Gibbs et al. (32) recently reported successful oral transmission of CJD to squirrel monkeys that had been allowed to eat brains, kidney and spleen tissues from animals that died with the disease. It seems reasonable to assume that natural CJD is also transmitted via the oral route perhaps through ingestion of infected sheep tissues.



The concept that CJD may have a zoonotic source has important public health implications. Brown's firm rejection of a zoonotic source for CJD may be premature.



REFERENCES

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THE AUTHOR REPLIES



I welcome the opportunity to respond to the letter of Davanipour et al. (1), and would immediately point out that my article was an attempt to evaluate all of the epidemiologic data bearing on Creutzfeldt-Jakob disease (CJD), not merely the zoonotic hypothesis. Taking each of their points in turn:



Davanipour's quotation from the article about groups with increased exposure to sheep not being "overrepresented among CJD patients" should have included the end of the sentence: "in any of the surveys shown in table 3," which explicitly included Masters et al. (2) collection of American patients, not his entire series, for the reason that the majority of non- American patients were either drawn from other national series in the table, or were unavoidably "selected" either by prior publication or by case referral to our laboratory. The conclusion was therefore not based on 308 of 1435 patients with occupational histories, but on statements made by the authors of each of the published national series, and in particular our own systematic study of CJD in France (3, 4), where we do have precise information about the occupational universe from which more than 250 cases (1968- 1980) have now been identified.



There follows an excellent summary of material already presented in the article about the possibility that CJD may be due to rare exposures to small amounts of virus in genetically predisposed human hosts, but Davanipour et al. should not confine thinking about this mechanism to scrapie virus exposure. As for serum anti-neurofilament antibody (and brain suspension in-vitro cell-fusing activity, also demonstrated in our laboratory), neither test is sufficiently specific to warrant any speculation about the frequency of unsuspected CJD virus infection, as was emphasized in the article.



The worldwide distribution of scrapie is indeed different from the distribution of CJD. Scrapie has never been endemic in Australia: the only cases occurred in a flock of imported sheep still under quarantine and immediately destroyed in 1952. Scrapie is still unreported in several other countries where CJD occurs, notably Japan, where a recent casecontrol study has in addition failed to find an association between the prevalence of CJD and exposure to any animals, including sheep, or consumption of animal products (5). None of these data absolutely disprove the zoonotic origin of CJD, but they surely do not argue in its favor.



Moreover, a study of scrapie in France has now been completed in which the regional frequency of scrapie and the interregional distribution of sheep products has been compared with the regional frequency of CJD (6). No scrapie-free sheep producing region was found mainly to supply an area of low CJD incidence, nor any scrapie-endemic region mainly to supply an area of high CJD incidence. For example, the southwestern region of France, an important sheep-producing area where scrapie is endemic, supplies all of its own needs (and has the lowest rate of CJD in the whole of France), and is also a main supplier of the Paris region (with the highest national rate of CJD). These observations constitute further evidence against the scrapie-CJD hypothesis, but again, do not formally exclude it.



As for the very interesting observation of CJD in high incidence among Libyan Jews in Israel, approximately half of these patients have now been identified as familial cases (Kahana E., personal communication, 1981), and since nothing is known about the occurrence of CJD in Libya itself, it is as plausible to consider genetic predisposition as dietary habits to be responsible for this unusual concentration of disease. The other data cited by Davanipour et al., although anecdotal, could be important, and deserve systematic investigation.



Contrary to the statement by Davanipour et al. scrapie virus has been extensively sought in sheep muscle, but never recovered. The single isolation in goat muscle, cited in the article, has never been verified. Spinal cord sections that may be present in chops, or even brain tissue, are equally unlikely sources of infection, since sheep are slaughtered at an age when detectable virus in the central nervous system is exceedingly rare. Although it is theoretically possible that virus might occur in muscle and brain tissue in amounts too small to be detected, visceral tissues are still the most likely source of potential contamination, as they have been documented to contain virus in both younger and older animals. As emphasized, it would make more sense to look at the consumption of kidneys and sausage casings than of brain or lamb.



Reports that are now beginning to appear of naturally occurring spongiform encephalopathies in species other than humans, sheep, and goats, are extremely interesting, but do not warrant the conclusion by Davanipour et al. that "scrapie virus certainly has a wider host range than sheep," any more than the assertion, for example, that mule deer are afflicted with kuru. Considerable study will be required to characterize the putative agents responsible for these new diseases. Incidentally, the paper by Bobowick et al. (7) does not report higher frequency of hog brain ingestion by CJD patients than matched controls, but rather an equally frequent ingestion in both groups. This is not the first misreading of their publication, and has always mystified the authors of that article.



The experimental transmission of CJD to goats cited by Davanipour et al., as well as the recent transmission of both kuru and CJD to goats (but not sheep) (8), are excellent recent examples of the progress being made in laboratory transmissions of the several spongiform encephalopathy viruses to different host species. Eventually, it is possible that all of these viruses may be transmitted to a virtually identical species range, and their biological properties found to depend on host passage history; but even if they were all to derive historically from a single virus, subsequent adaptation to different hosts might actually inhibit rather than facilitate natural crossing of species barriers at the present time.



The final statement challenged by Davanipour et al. reads as follows: "Apart from a few proven or highly suspicious cases of iatrogenic surgical transmissions of CJD, there does not exist a single documented instance of transmission via any of the possible routes—respiratory, oral, venereal, dermatologic, or percutaneous— by which the more conventional viruses spread among humans." In the article, evidence for oral infection by spongiform encephalopathy viruses, including experimental oral infection by CJD virus, was amply cited. Oral transmission of naturally acquired CJD nevertheless remains only a possibility, not an assumption. The distinction is not unimportant.



In summary, Davanipour et al. have culled from the article those facts which could be used to support their thesis that scrapie causes CJD in man, and have chosen to ignore those facts which conflict with this interpretation, or which suggest alternative explanations. Moreover, they have taken too seriously as a "firm rejection" the author's speculations, delivered from the armchair, and not appreciated that he continues to regard with an open mind the zoonotic hypothesis for CJD, but, all things considered, prefers the hypothesis of a genetic predisposition to inter-human viral transmission. This should under no circumstances be mistaken for anything more than an informed guess; indeed, if he may be excused one final quotation from Alice's Adventures in Wonderland, the author will conclude by insisting that throughout the review he has actually tried to follow Alice's own example: "and so she went on, taking first one side and then the other, and making quite a conversation of it altogether."



REFERENCES


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http://aje.oxfordjournals.org/content/115/1/145.full.pdf+html




http://aje.oxfordjournals.org/content/115/1/149.full.pdf




Neuroepidemiology. 1985;4(4):240-9.



Sheep consumption: a possible source of spongiform encephalopathy in humans.



Davanipour Z, Alter M, Sobel E, Callahan M.



Abstract



A fatal spongiform encephalopathy of sheep and goats (scrapie) shares many characteristics with Creutzfeldt-Jakob disease (CJD), a similar dementing illness of humans. To investigate the possibility that CJD is acquired by ingestion of contaminated sheep products, we collected information on production, slaughtering practices, and marketing of sheep in Pennsylvania. The study revealed that sheep were usually marketed before central nervous system signs of scrapie are expected to appear; breeds known to be susceptible to the disease were the most common breeds raised in the area; sheep were imported from other states including those with a high frequency of scrapie; use of veterinary services on the sheep farms investigated and, hence, opportunities to detect the disease were limited; sheep producers in the area knew little about scrapie despite the fact that the disease has been reported in the area, and animal organs including sheep organs were sometimes included in processed food. Therefore, it was concluded that in Pennsylvania there are some 'weak links' through which scrapie-infected animals could contaminate human food, and that consumption of these foods could perhaps account for spongiform encephalopathy in humans. The weak links observed are probably not unique to Pennsylvania. PMID: 3915057 [PubMed - indexed for MEDLINE]



http://www.ncbi.nlm.nih.gov/pubmed/3915057?dopt=Abstract




Atypical/Nor98 Scrapie Infectivity in Sheep Peripheral Tissues

Olivier Andréoletti1*, Leonor Orge2, Sylvie L. Benestad3, Vincent Beringue4, Claire Litaise1, Stéphanie Simon5, Annick Le Dur4, Hubert Laude4, Hugh Simmons6, Séverine Lugan1, Fabien Corbière1, Pierrette Costes1, Nathalie Morel5, François Schelcher1, Caroline Lacroux1

1 UMR INRA ENVT 1225, Interactions Hôtes Agents Pathogènes, Ecole Nationale Vétérinaire de Toulouse, Toulouse, France, 2 Laboratório Nacional de Investigação Veterinária, Lisboa, Portugal, 3 National Veterinary Institute, Oslo, Norway, 4 INRA UR892, Virologie et Immunologie Moléculaires, INRA, F-78350 Jouy-en-Josas, France, 5 CEA, Service de Pharmacologie et d'Immunoanalyse, IBiTec-S, DSV, CEA/Saclay, Gif sur Yvette cedex, France, 6 VLA Weybridge, ASU, Addlestone, Surrey, United Kingdom

Abstract Top

Atypical/Nor98 scrapie was first identified in 1998 in Norway. It is now considered as a worldwide disease of small ruminants and currently represents a significant part of the detected transmissible spongiform encephalopathies (TSE) cases in Europe. Atypical/Nor98 scrapie cases were reported in ARR/ARR sheep, which are highly resistant to BSE and other small ruminants TSE agents. The biology and pathogenesis of the Atypical/Nor98 scrapie agent in its natural host is still poorly understood. However, based on the absence of detectable abnormal PrP in peripheral tissues of affected individuals, human and animal exposure risk to this specific TSE agent has been considered low. In this study we demonstrate that infectivity can accumulate, even if no abnormal PrP is detectable, in lymphoid tissues, nerves, and muscles from natural and/or experimental Atypical/Nor98 scrapie cases. Evidence is provided that, in comparison to other TSE agents, samples containing Atypical/Nor98 scrapie infectivity could remain PrPSc negative. This feature will impact detection of Atypical/Nor98 scrapie cases in the field, and highlights the need to review current evaluations of the disease prevalence and potential transmissibility. Finally, an estimate is made of the infectivity loads accumulating in peripheral tissues in both Atypical/Nor98 and classical scrapie cases that currently enter the food chain. The results obtained indicate that dietary exposure risk to small ruminants TSE agents may be higher than commonly believed.

Author Summary Top

Following the bovine spongiform encephalopathy (BSE) crisis and the identification of its zoonotic properties, a sanitary policy has been implemented based on both eradication of transmissible spongiform encephalopathies (TSE) in food-producing animals and exclusion of known infectious materials from the food chain. Atypical/Nor98 scrapie is a prion disease of small ruminants identified worldwide. Currently it represents a significant part of the TSE cases detected in Europe. The restricted tissue distribution of Atypical/Nor98 scrapie agent in its natural host and the low detected prevalence of secondary cases in affected flocks meant that it is believed to be a poorly transmissible disease. This has led to the view that Atypical/Nor98 scrapie is a spontaneous disorder for which human and animal exposure risk remains low. In this study we demonstrate that in affected individuals, Atypical/Nor98 scrapie agent can disseminate in lymphoid tissues, nerves, and muscles, challenging the idea that it is a brain-restricted infectious agent. Evidence for the deficiencies in the current methods applied for monitoring Atypical/Nor98 scrapie is provided that would indicate an underestimation in the prevalence in the general population and in the affected flocks. These elements challenge the hypothesis on the biology of this recently identified TSE agent.

Citation: Andréoletti O, Orge L, Benestad SL, Beringue V, Litaise C, et al. (2011) Atypical/Nor98 Scrapie Infectivity in Sheep Peripheral Tissues. PLoS Pathog 7(2): e1001285. doi:10.1371/journal.ppat.1001285

Editor: David Westaway, University of Alberta, Canada

Received: June 21, 2010; Accepted: January 10, 2011; Published: February 10, 2011

Copyright: © 2011 Andréoletti 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: The different parts of this work were funded by (i) The Food Standard Agency (UK) M03058, (ii) the FP7 EU project 'Priority' (243950 FP7-KBBE KBBE-2009-1-2-06), and (iii) Programme opérationnel de Coopération territoriale Espagne - France - Andorre 2007-2013 EFA85/08-COTSA. Lymphoid tissue collection in Portuguese sheep was supported by AGROS 558 (PO AGRO 8.1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

* E-mail: o.andreoletti@envt.fr

snip...

However, this hypothesis is questioned by the evidence reported here that a negative PrPSc testing result could be observed in animals harbouring high infectious titre in their brain and that the infectious agent can be present in peripheral tissues of Atypical/Nor98 scrapie incubating sheep. TSE are considered to be transmitted following oral exposure; initial uptake is followed by a peripheral replication phase which is generally associated with a dissemination of the agent in the lymphoid system and the deposition of large amounts of PrPSc. This peripheral replication phase is later followed by the entry of the infectious agent into the CNS through the autonomic nervous system [25], [27], [35], [36]. However, in several situations, like BSE in cattle [41], [42], [43] or classical scrapie in ARR heterozygote sheep [44], [45], the involvement of secondary lymphoid system is marginal, which does not preclude central neuro-invasion through the autonomic nervous system [46]. It could be proposed that Atypical Scrapie/Nor98 might occur following oral exposure to a TSE agent, which would spread marginally in lymphoid tissues before neuro-invasion. The slow propagation of Atypical Scrapie/Nor98 in its host (long incubation period) and the impaired detection sensitivity level of PrPSc based assays would explain the apparent old age of detected cases.

The results presented here are insufficient to rule out the hypothesis of a spontaneous/non contagious disorder or to consider this alternative scenario as a plausible hypothesis. Indeed, the presence of Atypical scrapie/Nor98 infectivity in peripheral tissues could be alternatively due to the centripetal spreading of the agent from the CNS. However, our findings point out that further clarifications on Atypical/Nor98 scrapie agent biology are needed before accepting that this TSE is a spontaneous and non contagious disorder of small ruminants. Assessing Atypical/Nor98 scrapie transmissibility through oral route in natural host and presence in placenta and in colostrum/milk (which are considered as major sources for TSE transmission between small ruminants) [28], [32] will provide crucial data.

The presence of infectivity in peripheral tissues that enter the food chain clearly indicates that the risk of dietary exposure to Atypical/Nor98 scrapie cannot be disregarded. However, according to our observations, in comparison to the brain, the infectious titres in the peripheral tissues were five log10 lower in Atypical/Nor98 scrapie than in classical scrapie. Therefore, the reduction of the relative exposure risk following SRM removal (CNS, head, spleen and ileum) is probably significantly higher in Atypical/Nor98 scrapie cases than in classical scrapie cases. However, considering the currently estimated prevalence of Atypical/Nor98 scrapie in healthy slaughtered EU population [10], it is probable that atypical scrapie infectivity enters in the food chain despite the prevention measures in force.

Finally, the capacity of Atypical/Nor98 scrapie agent (and more generally of small ruminants TSE agents) to cross species barrier that naturally limits the transmission risk is insufficiently documented. Recently, the transmission of an Atypical/Nor98 scrapie isolate was reported into transgenic mice over-expressing the porcine PrP [47]. Such results cannot directly be extrapolated to natural exposure conditions and natural hosts. However, they underline the urgent need for further investigations on the potential capacity of Atypical/Nor98 scrapie to propagate in other species than small ruminants.

snip...please see full text thanks to the Authors and plospathogens.org/


http://www.plospathogens.org/article/info%3Adoi%2F10.1371%2Fjournal.ppat.1001285;jsessionid=CECDA9978AB8F920FB2ED52F4EB71071.ambra01



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 . - 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



Scrapie

The two Commissions discussed the issue of ‘atypical’ scrapie in terms of notification requirements and the issue of the host genetic resistance. In response to questions of Members, the Code Commission clarified that ‘classical’ scrapie is reportable to the OIE but that ‘atypical’ scrapie is not reportable (in accordance with the recommendations made by the ad hoc Group on Atypical Scrapie and Atypical BSE, which met in November 2007). However, the sharing of scientific information on ‘atypical’ scrapie is encouraged. At this time, the Code Commission considered that more scientific information would be needed to fully address the issues associated with host genotype.

EU comment

4

OIE Terrestrial Animal Health Standards Commission / September 2010

The EU takes note of the fact that atypical scrapie is not an OIE listed disease. Nevertheless, it will remain notifiable in the EU. Moreover it must be stressed that any emergence of this disease should be notified to the OIE by Members and that scientific data should continue to be gathered.

snip...

Zoonotic Potential

Has transmission to humans been proven? (with the exception of artificial

circumstances) AND

Is human infection associated with severe consequences? (death or prolonged illness)

http://ec.europa.eu/food/international/organisations/docs/EU_comments_OIE_terrestrial_animal_health_code_en.pdf



Monday, November 30, 2009

USDA AND OIE COLLABORATE TO EXCLUDE ATYPICAL SCRAPIE NOR-98 ANIMAL HEALTH CODE

http://nor-98.blogspot.com/2009/11/usda-and-oie-collaborate-to-exclude.html


Sunday, December 12, 2010

EFSA reviews BSE/TSE infectivity in small ruminant tissues News Story 2 December 2010

http://transmissiblespongiformencephalopathy.blogspot.com/2010/12/efsa-reviews-bsetse-infectivity-in.html



Thursday, November 18, 2010

Increased susceptibility of human-PrP transgenic mice to bovine spongiform encephalopathy following passage in sheep

http://bse-atypical.blogspot.com/2010/11/increased-susceptibility-of-human-prp.html


Thursday, December 23, 2010

Molecular Typing of Protease-Resistant Prion Protein in Transmissible Spongiform Encephalopathies of Small Ruminants, France, 2002–2009 Volume 17, Number 1–January 2011

http://transmissiblespongiformencephalopathy.blogspot.com/2010/12/molecular-typing-of-protease-resistant.html


Sunday, October 3, 2010

Scrapie, Nor-98 atypical Scrapie, and BSE in sheep and goats North America, who's looking ?

http://nor-98.blogspot.com/2010/10/scrapie-nor-98-atypical-scrapie-and-bse.html


http://nor-98.blogspot.com/



Monday, November 22, 2010

Atypical transmissible spongiform encephalopathies in ruminants: a challenge for disease surveillance and control

REVIEW ARTICLES

http://transmissiblespongiformencephalopathy.blogspot.com/2010/11/atypical-transmissible-spongiform.html



Sunday, April 18, 2010

SCRAPIE AND ATYPICAL SCRAPIE TRANSMISSION STUDIES A REVIEW 2010

http://scrapie-usa.blogspot.com/2010/04/scrapie-and-atypical-scrapie.html


Wednesday, January 19, 2011

EFSA and ECDC review scientific evidence on possible links between TSEs in animals and humans Webnachricht 19 Januar 2011

http://transmissiblespongiformencephalopathy.blogspot.com/2011/01/efsa-and-ecdc-review-scientific.html



Tuesday, January 18, 2011

Agent strain variation in human prion disease: insights from a molecular and pathological review of the National Institutes of Health series of experimentally transmitted disease

http://transmissiblespongiformencephalopathy.blogspot.com/2011/01/agent-strain-variation-in-human-prion.html


EVIDENCE OF SCRAPIE IN SHEEP AS A RESULT OF FOOD BORNE EXPOSURE

This is provided by the statistically significant increase in the incidence of sheep scrape from 1985, as determined from analyses of the submissions made to VI Centres, and from individual case and flock incident studies. ........

http://web.archive.org/web/20010305222246/www.bseinquiry.gov.uk/files/yb/1994/02/07002001.pdf



RISK OF BSE TO SHEEP VIA FEED

http://collections.europarchive.org/tna/20090114022605/http://www.bseinquiry.gov.uk/files/sc/seac31/tab01.pdf



Marion Simmons communicated surprising evidence for oral transmissibility of Nor98/atypical scrapie in neonatal sheep and although bioassay is ongoing, infectivity of the distal ileum of 12 and 24 month infected sheep is positive in Tg338 mice.

http://www.goatbse.eu/site/index.php?option=com_content&view=article&id=94:minutes-workshop-2010&catid=9:popular&Itemid=22


SUMMARY REPORTS OF MAFF BSE TRANSMISSION STUDIES AT THE CVL ;

http://collections.europarchive.org/tna/20090114023010/http://www.bseinquiry.gov.uk/files/sc/seac18/tab02b.pdf



THE RISK TO HUMANS FROM SHEEP;

http://collections.europarchive.org/tna/20090114022915/http://www.bseinquiry.gov.uk/files/sc/seac24/tab03.pdf



EXPERIMENTAL TRANSMISSION OF BSE TO SHEEP

http://collections.europarchive.org/tna/20090114023211/http://www.bseinquiry.gov.uk/files/sc/seac25/tab05.pdf



SHEEP AND BSE

PERSONAL AND CONFIDENTIAL

SHEEP AND BSE

A. The experimental transmission of BSE to sheep.

Studies have shown that the ''negative'' line NPU flock of Cheviots can be experimentally infected with BSE by intracerebral (ic) or oral challenge (the latter being equivalent to 0.5 gram of a pool of four cow brains from animals confirmed to have BSE).

http://collections.europarchive.org/tna/20090506010048/http://www.bseinquiry.gov.uk/files/sc/seac33/tab02.pdf



RB264

BSE - TRANSMISSION STUDIES

http://collections.europarchive.org/tna/20090113230127/http://www.bseinquiry.gov.uk/files/sc/Seac06/tab06.pdf



1: J Infect Dis 1980 Aug;142(2):205-8

Oral transmission of kuru, Creutzfeldt-Jakob disease, and scrapie to nonhuman primates.

Gibbs CJ Jr, Amyx HL, Bacote A, Masters CL, Gajdusek DC.

Kuru and Creutzfeldt-Jakob disease of humans and scrapie disease of sheep and goats were transmitted to squirrel monkeys (Saimiri sciureus) that were exposed to the infectious agents only by their nonforced consumption of known infectious tissues. The asymptomatic incubation period in the one monkey exposed to the virus of kuru was 36 months; that in the two monkeys exposed to the virus of Creutzfeldt-Jakob disease was 23 and 27 months, respectively; and that in the two monkeys exposed to the virus of scrapie was 25 and 32 months, respectively. Careful physical examination of the buccal cavities of all of the monkeys failed to reveal signs or oral lesions. One additional monkey similarly exposed to kuru has remained asymptomatic during the 39 months that it has been under observation.

snip...

The successful transmission of kuru, Creutzfeldt-Jakob disease, and scrapie by natural feeding to squirrel monkeys that we have reported provides further grounds for concern that scrapie-infected meat may occasionally give rise in humans to Creutzfeldt-Jakob disease.

PMID: 6997404

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6997404&dopt=Abstract



12/10/76 AGRICULTURAL RESEARCH COUNCIL REPORT OF THE ADVISORY COMMITTE ON SCRAPIE Office Note CHAIRMAN: PROFESSOR PETER WILDY

snip...

A The Present Position with respect to Scrapie A] The Problem Scrapie is a natural disease of sheep and goats. It is a slow and inexorably progressive degenerative disorder of the nervous system and it ia fatal. It is enzootic in the United Kingdom but not in all countries. The field problem has been reviewed by a MAFF working group (ARC 35/77). It is difficult to assess the incidence in Britain for a variety of reasons but the disease causes serious financial loss; it is estimated that it cost Swaledale breeders alone $l.7 M during the five years 1971-1975. A further inestimable loss arises from the closure of certain export markets, in particular those of the United States, to British sheep. It is clear that scrapie in sheep is important commercially and for that reason alone effective measures to control it should be devised as quickly as possible. Recently the question has again been brought up as to whether scrapie is transmissible to man. This has followed reports that the disease has been transmitted to primates.

One particularly lurid speculation (Gajdusek 1977) conjectures that the agents of scrapie, kuru, Creutzfeldt-Jakob disease and transmissible encephalopathy of mink are varieties of a single "virus". The U.S. Department of Agriculture concluded that it could "no longer justify or permit scrapie-blood line and scrapie-exposed sheep and goats to be processed for human or animal food at slaughter or rendering plants" (ARC 84/77)" The problem is emphasised by the finding that some strains of scrapie produce lesions identical to the once which characterise the human dementias" Whether true or not. the hypothesis that these agents might be transmissible to man raises two considerations. First, the safety of laboratory personnel requires prompt attention. Second, action such as the "scorched meat" policy of USDA makes the solution of the acrapie problem urgent if the sheep industry is not to suffer grievously.

snip...

76/10.12/4.6

http://web.archive.org/web/20010305223125/www.bseinquiry.gov.uk/files/yb/1976/10/12004001.pdf



Nature. 1972 Mar 10;236(5341):73-4.

Transmission of scrapie to the cynomolgus monkey (Macaca fascicularis).

Gibbs CJ Jr, Gajdusek DC. Nature 236, 73 - 74 (10 March 1972); doi:10.1038/236073a0

Transmission of Scrapie to the Cynomolgus Monkey (Macaca fascicularis)

C. J. GIBBS jun. & D. C. GAJDUSEK National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, Maryland

SCRAPIE has been transmitted to the cynomolgus, or crab-eating, monkey (Macaca fascicularis) with an incubation period of more than 5 yr from the time of intracerebral inoculation of scrapie-infected mouse brain. The animal developed a chronic central nervous system degeneration, with ataxia, tremor and myoclonus with associated severe scrapie-like pathology of intensive astroglial hypertrophy and proliferation, neuronal vacuolation and status spongiosus of grey matter. The strain of scrapie virus used was the eighth passage in Swiss mice (NIH) of a Compton strain of scrapie obtained as ninth intracerebral passage of the agent in goat brain, from Dr R. L. Chandler (ARC, Compton, Berkshire).

http://www.nature.com/nature/journal/v236/n5341/abs/236073a0.html


Epidemiology of Scrapie in the United States 1977

http://web.archive.org/web/20030513212324/http://www.bseinquiry.gov.uk/files/mb/m08b/tab64.pdf


Suspect symptoms

What if you can catch old-fashioned CJD by eating meat from a sheep infected with scrapie?

28 Mar 01

Like lambs to the slaughter 31 March 2001 by Debora MacKenzie Magazine issue 2284. Subscribe and get 4 free issues. FOUR years ago, Terry Singeltary watched his mother die horribly from a degenerative brain disease. Doctors told him it was Alzheimer's, but Singeltary was suspicious. The diagnosis didn't fit her violent symptoms, and he demanded an autopsy. It showed she had died of sporadic Creutzfeldt-Jakob disease.

Most doctors believe that sCJD is caused by a prion protein deforming by chance into a killer. But Singeltary thinks otherwise. He is one of a number of campaigners who say that some sCJD, like the variant CJD related to BSE, is caused by eating meat from infected animals. Their suspicions have focused on sheep carrying scrapie, a BSE-like disease that is widespread in flocks across Europe and North America.

Now scientists in France have stumbled across new evidence that adds weight to the campaigners' fears. To their complete surprise, the researchers found that one strain of scrapie causes the same brain damage in mice as sCJD.

"This means we cannot rule out that at least some sCJD may be caused by some strains of scrapie," says team member Jean-Philippe Deslys of the French Atomic Energy Commission's medical research laboratory in Fontenay-aux-Roses, south-west of Paris. Hans Kretschmar of the University of Göttingen, who coordinates CJD surveillance in Germany, is so concerned by the findings that he now wants to trawl back through past sCJD cases to see if any might have been caused by eating infected mutton or lamb.

Scrapie has been around for centuries and until now there has been no evidence that it poses a risk to human health. But if the French finding means that scrapie can cause sCJD in people, countries around the world may have overlooked a CJD crisis to rival that caused by BSE.

Deslys and colleagues were originally studying vCJD, not sCJD. They injected the brains of macaque monkeys with brain from BSE cattle, and from French and British vCJD patients. The brain damage and clinical symptoms in the monkeys were the same for all three. Mice injected with the original sets of brain tissue or with infected monkey brain also developed the same symptoms.

As a control experiment, the team also injected mice with brain tissue from people and animals with other prion diseases: a French case of sCJD; a French patient who caught sCJD from human-derived growth hormone; sheep with a French strain of scrapie; and mice carrying a prion derived from an American scrapie strain. As expected, they all affected the brain in a different way from BSE and vCJD. But while the American strain of scrapie caused different damage from sCJD, the French strain produced exactly the same pathology.

"The main evidence that scrapie does not affect humans has been epidemiology," says Moira Bruce of the neuropathogenesis unit of the Institute for Animal Health in Edinburgh, who was a member of the same team as Deslys. "You see about the same incidence of the disease everywhere, whether or not there are many sheep, and in countries such as New Zealand with no scrapie." In the only previous comparisons of sCJD and scrapie in mice, Bruce found they were dissimilar.

But there are more than 20 strains of scrapie, and six of sCJD. "You would not necessarily see a relationship between the two with epidemiology if only some strains affect only some people," says Deslys. Bruce is cautious about the mouse results, but agrees they require further investigation. Other trials of scrapie and sCJD in mice, she says, are in progress.

People can have three different genetic variations of the human prion protein, and each type of protein can fold up two different ways. Kretschmar has found that these six combinations correspond to six clinical types of sCJD: each type of normal prion produces a particular pathology when it spontaneously deforms to produce sCJD.

But if these proteins deform because of infection with a disease-causing prion, the relationship between pathology and prion type should be different, as it is in vCJD. "If we look at brain samples from sporadic CJD cases and find some that do not fit the pattern," says Kretschmar, "that could mean they were caused by infection."

There are 250 deaths per year from sCJD in the US, and a similar incidence elsewhere. Singeltary and other US activists think that some of these people died after eating contaminated meat or "nutritional" pills containing dried animal brain. Governments will have a hard time facing activists like Singeltary if it turns out that some sCJD isn't as spontaneous as doctors have insisted.

Deslys's work on macaques also provides further proof that the human disease vCJD is caused by BSE. And the experiments showed that vCJD is much more virulent to primates than BSE, even when injected into the bloodstream rather than the brain. This, says Deslys, means that there is an even bigger risk than we thought that vCJD can be passed from one patient to another through contaminated blood transfusions and surgical instruments.

http://www.newscientist.com/article/mg16922840.300-like-lambs-to-the-slaughter.html


Monday, December 14, 2009

Similarities between Forms of Sheep Scrapie and Creutzfeldt-Jakob Disease Are Encoded by Distinct Prion Types

(hmmm, this is getting interesting now...TSS)

Sporadic CJD type 1 and atypical/ Nor98 scrapie are characterized by fine (reticular) deposits,

see also ;

All of the Heidenhain variants were of the methionine/ methionine type 1 molecular subtype.

http://cjdusa.blogspot.com/2009/09/co-existence-of-scrapie-prion-protein.html


see full text ;

Monday, December 14, 2009

Similarities between Forms of Sheep Scrapie and Creutzfeldt-Jakob Disease Are Encoded by Distinct Prion Types

http://nor-98.blogspot.com/2009/12/similarities-between-forms-of-sheep.html


Tuesday, April 28, 2009

Nor98-like Scrapie in the United States of America

http://nor-98.blogspot.com/2009/04/nor98-like-scrapie-in-united-states-of.html


Wednesday, March 3, 2010

NOR-98 ATYPICAL SCRAPIE USA 4 CASES DETECTED JANUARY 2010

http://nor-98.blogspot.com/2010/03/nor-98-atypical-scrapie-usa-4-cases.html


P03.141

Aspects of the Cerebellar Neuropathology in Nor98

Gavier-Widén, D1; Benestad, SL2; Ottander, L1; Westergren, E1 1National Veterinary Insitute, Sweden; 2National Veterinary Institute,

Norway Nor98 is a prion disease of old sheep and goats. This atypical form of scrapie was first described in Norway in 1998. Several features of Nor98 were shown to be different from classical scrapie including the distribution of disease associated prion protein (PrPd) accumulation in the brain. The cerebellum is generally the most affected brain area in Nor98. The study here presented aimed at adding information on the neuropathology in the cerebellum of Nor98 naturally affected sheep of various genotypes in Sweden and Norway. A panel of histochemical and immunohistochemical (IHC) stainings such as IHC for PrPd, synaptophysin, glial fibrillary acidic protein, amyloid, and cell markers for phagocytic cells were conducted. The type of histological lesions and tissue reactions were evaluated. The types of PrPd deposition were characterized. The cerebellar cortex was regularly affected, even though there was a variation in the severity of the lesions from case to case. Neuropil vacuolation was more marked in the molecular layer, but affected also the granular cell layer. There was a loss of granule cells. Punctate deposition of PrPd was characteristic. It was morphologically and in distribution identical with that of synaptophysin, suggesting that PrPd accumulates in the synaptic structures. PrPd was also observed in the granule cell layer and in the white matter. The pathology features of Nor98 in the cerebellum of the affected sheep showed similarities with those of sporadic Creutzfeldt-Jakob disease in humans.

***The pathology features of Nor98 in the cerebellum of the affected sheep showed similarities with those of sporadic Creutzfeldt-Jakob disease in humans.

http://www.prion2007.com/pdf/Prion%20Book%20of%20Abstracts.pdf


PR-26

NOR98 SHOWS MOLECULAR FEATURES REMINISCENT OF GSS

R. Nonno1, E. Esposito1, G. Vaccari1, E. Bandino2, M. Conte1, B. Chiappini1, S. Marcon1, M. Di Bari1, S.L. Benestad3, U. Agrimi1 1 Istituto Superiore di Sanità, Department of Food Safety and Veterinary Public Health, Rome, Italy (romolo.nonno@iss.it); 2 Istituto Zooprofilattico della Sardegna, Sassari, Italy; 3 National Veterinary Institute, Department of Pathology, Oslo, Norway

Molecular variants of PrPSc are being increasingly investigated in sheep scrapie and are generally referred to as "atypical" scrapie, as opposed to "classical scrapie". Among the atypical group, Nor98 seems to be the best identified. We studied the molecular properties of Italian and Norwegian Nor98 samples by WB analysis of brain homogenates, either untreated, digested with different concentrations of proteinase K, or subjected to enzymatic deglycosylation. The identity of PrP fragments was inferred by means of antibodies spanning the full PrP sequence. We found that undigested brain homogenates contain a Nor98-specific PrP fragment migrating at 11 kDa (PrP11), truncated at both the C-terminus and the N-terminus, and not N-glycosylated. After mild PK digestion, Nor98 displayed full-length PrP (FL-PrP) and N-glycosylated C-terminal fragments (CTF), along with increased levels of PrP11. Proteinase K digestion curves (0,006-6,4 mg/ml) showed that FL-PrP and CTF are mainly digested above 0,01 mg/ml, while PrP11 is not entirely digested even at the highest concentrations, similarly to PrP27-30 associated with classical scrapie. Above 0,2 mg/ml PK, most Nor98 samples showed only PrP11 and a fragment of 17 kDa with the same properties of PrP11, that was tentatively identified as a dimer of PrP11. Detergent solubility studies showed that PrP11 is insoluble in 2% sodium laurylsorcosine and is mainly produced from detergentsoluble, full-length PrPSc. Furthermore, among Italian scrapie isolates, we found that a sample with molecular and pathological properties consistent with Nor98 showed plaque-like deposits of PrPSc in the thalamus when the brain was analysed by PrPSc immunohistochemistry. Taken together, our results show that the distinctive pathological feature of Nor98 is a PrP fragment spanning amino acids ~ 90-155. This fragment is produced by successive N-terminal and C-terminal cleavages from a full-length and largely detergent-soluble PrPSc, is produced in vivo and is extremely resistant to PK digestion.

*** Intriguingly, these conclusions suggest that some pathological features of Nor98 are reminiscent of Gerstmann-Sträussler-Scheinker disease.

119

http://www.neuroprion.com/pdf_docs/conferences/prion2006/abstract_book.pdf


A newly identified type of scrapie agent can naturally infect sheep with resistant PrP genotypes

Annick Le Dur*,?, Vincent Béringue*,?, Olivier Andréoletti?, Fabienne Reine*, Thanh Lan Laï*, Thierry Baron§, Bjørn Bratberg¶, Jean-Luc Vilotte?, Pierre Sarradin**, Sylvie L. Benestad¶, and Hubert Laude*,? +Author Affiliations

*Virologie Immunologie Moléculaires and ?Génétique Biochimique et Cytogénétique, Institut National de la Recherche Agronomique, 78350 Jouy-en-Josas, France; ?Unité Mixte de Recherche, Institut National de la Recherche Agronomique-Ecole Nationale Vétérinaire de Toulouse, Interactions Hôte Agent Pathogène, 31066 Toulouse, France; §Agence Française de Sécurité Sanitaire des Aliments, Unité Agents Transmissibles Non Conventionnels, 69364 Lyon, France; **Pathologie Infectieuse et Immunologie, Institut National de la Recherche Agronomique, 37380 Nouzilly, France; and ¶Department of Pathology, National Veterinary Institute, 0033 Oslo, Norway

***Edited by Stanley B. Prusiner, University of California, San Francisco, CA (received for review March 21, 2005)

Abstract Scrapie in small ruminants belongs to transmissible spongiform encephalopathies (TSEs), or prion diseases, a family of fatal neurodegenerative disorders that affect humans and animals and can transmit within and between species by ingestion or inoculation. Conversion of the host-encoded prion protein (PrP), normal cellular PrP (PrPc), into a misfolded form, abnormal PrP (PrPSc), plays a key role in TSE transmission and pathogenesis. The intensified surveillance of scrapie in the European Union, together with the improvement of PrPSc detection techniques, has led to the discovery of a growing number of so-called atypical scrapie cases. These include clinical Nor98 cases first identified in Norwegian sheep on the basis of unusual pathological and PrPSc molecular features and "cases" that produced discordant responses in the rapid tests currently applied to the large-scale random screening of slaughtered or fallen animals. Worryingly, a substantial proportion of such cases involved sheep with PrP genotypes known until now to confer natural resistance to conventional scrapie. Here we report that both Nor98 and discordant cases, including three sheep homozygous for the resistant PrPARR allele (A136R154R171), efficiently transmitted the disease to transgenic mice expressing ovine PrP, and that they shared unique biological and biochemical features upon propagation in mice. *** These observations support the view that a truly infectious TSE agent, unrecognized until recently, infects sheep and goat flocks and may have important implications in terms of scrapie control and public health.

http://www.pnas.org/content/102/44/16031.abstract


Monday, December 1, 2008

When Atypical Scrapie cross species barriers

Authors

Andreoletti O., Herva M. H., Cassard H., Espinosa J. C., Lacroux C., Simon S., Padilla D., Benestad S. L., Lantier F., Schelcher F., Grassi J., Torres, J. M., UMR INRA ENVT 1225, Ecole Nationale Veterinaire de Toulouse.France; ICISA-INlA, Madrid, Spain; CEA, IBiTec-5, DSV, CEA/Saclay, Gif sur Yvette cedex, France; National Veterinary Institute, Postboks 750 Sentrum, 0106 Oslo, Norway, INRA IASP, Centre INRA de Tours, 3738O Nouzilly, France.

Content

Atypical scrapie is a TSE occurring in small ruminants and harbouring peculiar clinical, epidemiological and biochemical properties. Currently this form of disease is identified in a large number of countries. In this study we report the transmission of an atypical scrapie isolate through different species barriers as modeled by transgenic mice (Tg) expressing different species PRP sequence.

The donor isolate was collected in 1995 in a French commercial sheep flock. inoculation into AHQ/AHQ sheep induced a disease which had all neuro-pathological and biochemical characteristics of atypical scrapie. Transmitted into Transgenic mice expressing either ovine or PrPc, the isolate retained all the described characteristics of atypical scrapie.

Surprisingly the TSE agent characteristics were dramatically different v/hen passaged into Tg bovine mice. The recovered TSE agent had biological and biochemical characteristics similar to those of atypical BSE L in the same mouse model. Moreover, whereas no other TSE agent than BSE were shown to transmit into Tg porcine mice, atypical scrapie was able to develop into this model, albeit with low attack rate on first passage.

Furthermore, after adaptation in the porcine mouse model this prion showed similar biological and biochemical characteristics than BSE adapted to this porcine mouse model. Altogether these data indicate.

(i) the unsuspected potential abilities of atypical scrapie to cross species barriers

(ii) the possible capacity of this agent to acquire new characteristics when crossing species barrier

These findings raise some interrogation on the concept of TSE strain and on the origin of the diversity of the TSE agents and could have consequences on field TSE control measures.

http://www.neuroprion.org/resources/pdf_docs/conferences/prion2008/abstract-book-prion2008.pdf



Tuesday, April 28, 2009

Nor98-like Scrapie in the United States of America

http://nor-98.blogspot.com/2009/04/nor98-like-scrapie-in-united-states-of.html


Sunday, April 18, 2010

SCRAPIE AND ATYPICAL SCRAPIE TRANSMISSION STUDIES A REVIEW 2010

http://scrapie-usa.blogspot.com/2010/04/scrapie-and-atypical-scrapie.html


Scrapie USA

http://scrapie-usa.blogspot.com/


Sunday, March 28, 2010

Nor-98 atypical Scrapie, atypical BSE, spontaneous TSE, trade policy, sound science ?

http://nor-98.blogspot.com/2010/03/nor-98-atypical-scrapie-atypical-bse.html


Sunday, October 3, 2010

Scrapie, Nor-98 atypical Scrapie, and BSE in sheep and goats North America, who's looking ?

http://nor-98.blogspot.com/2010/10/scrapie-nor-98-atypical-scrapie-and-bse.html


Heidenhain Variant Creutzfeldt Jakob Disease autopsy case report 'MOM'

DIVISION OF NEUROPATHOLOGY University of Texas Medical Branch 114 McCullough Bldg. Galveston, Texas 77555-0785

FAX COVER SHEET

DATE: 4-23-98

TO: Mr. Terry Singeltary @ -------

FROM: Gerald Campbell

FAX: (409) 772-5315 PHONE: (409) 772-2881

Number of Pages (including cover sheet) Message *CONFIDENTIALITY NOTICE*

This document accompanying this transmission contains confidential information belonging to the sender that is legally privileged. This information is intended only for the use of the individual or entry names above. If you are not the intended recipient, you are hereby notified that any disclosure, copying distribution, or the taking of any action in reliances on the contents of this telefaxed information is strictly prohibited. If you received this telefax in error, please notify us by telephone immediately to arrange for return of the original documents. -------------------------- Patient Account: 90000014-518 Med. Rec. No.: (0160)118511Q Patient Name: POULTER, BARBARA Age: 63 YRS DOB: 10/17/34 Sex: F Admitting Race: C

Attending Dr.: Date / Time Admitted : 12/14/97 1228 Copies to UTMB University of Texas Medical Branch Galveston, Texas 77555-0543 (409) 772-1238 Fax (409) 772-5683 Pathology Report

FINAL AUTOPSY DIAGNOSIS Autopsy' Office (409)772-2858

Autopsy NO.: AU-97-00435

AUTOPSY INFORMATION: Occupation: Unknown Birthplace: Unknown Residence: Crystal Beach Date/Time of Death: 12/14/97 13:30 Date/Time of Autopsy: 12/15/97 15:00 Pathologist/Resident: Pencil/Fernandez Service: Private Restriction: Brain only

FINAL AUTOPSY DIAGNOSIS

I. Brain: Creutzfeldt-Jakob disease, Heidenhain variant.

http://creutzfeldt-jakob-disease.blogspot.com/2008/07/heidenhain-variant-creutzfeldt-jakob.html



Wednesday, December 29, 2010

TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHY PRION END OF YEAR REPORT DECEMBER 29, 2010

http://transmissiblespongiformencephalopathy.blogspot.com/2010/12/transmissible-spongiform-encephalopathy.html


Saturday, December 18, 2010

OIE Global Conference on Wildlife Animal Health and Biodiversity - Preparing for the Future (TSE AND PRIONS) Paris (France), 23-25 February 2011

snip...

Greetings,

Thank for your support to the OIE objectives for a safe world.

NOT !

I see again that the OIE has done little to help eradicate all animal TSE from the globe, and in fact in my opinion, have help enhance the spread of BSE and other animal TSE globally by their industry friendly regulations. I tried to warn the OIE in 2002 about CWD and the potential, but very real threat of CWD to humans. I was told that they were seriously considering this. what happened ? NOW, the OIE and the USDA collaborate to make legal the trading of all strains of atypical BSE legal, and in fact have done so with the atypical scrapie, when science has made perfectly clear the risk factors to humans and other species. I have said it once (see below), and i will say again ;

"THE OIE has now shown they are nothing more than a National Trading Brokerage for all strains of animal TSE. AS i said before, OIE should hang up there jock strap now, since it appears they will buckle every time a country makes some political hay about trade protocol, commodities and futures. IF they are not going to be science based, they should do everyone a favor and dissolve there organization."

NOW, some history on the failed OIE BSE/TSE policy, and why the OIE allowed BSE and other TSE to spread around the globe $$$

snip...

http://transmissiblespongiformencephalopathy.blogspot.com/2010/12/oie-global-conference-on-wildlife.html



JOURNAL OF NEUROLOGY

MARCH 26, 2003

RE-Monitoring the occurrence of emerging forms of Creutzfeldt-Jakob disease in the United States

http://www.neurology.org/cgi/eletters/60/2/176#535


Newsdesk

The Lancet Infectious Diseases, Volume 3, Issue 8, Page 463, August 2003

doi:10.1016/S1473-3099(03)00715-1Cite or Link Using DOI

Tracking spongiform encephalopathies in North America

Xavier Bosch

"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.

http://linkinghub.elsevier.com/retrieve/pii/S1473309903007151


http://www.thelancet.com/journals/laninf/article/PIIS1473-3099(03)00715-1/fulltext


http://www.mdconsult.com/das/article/body/180784492-2/jorg=journal&source=&sp=13979213&sid=0/N/368742/1.html?issn=14733099



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

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. FREE FULL TEXT

http://jama.ama-assn.org/cgi/content/extract/285/6/733?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=singeltary&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT



http://jama.ama-assn.org/cgi/content/full/285/6/733?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=singeltary&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT



2 January 2000

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

http://www.bmj.com/cgi/eletters/320/7226/8/b#6117



15 November 1999

British Medical Journal vCJD in the USA * BSE in U.S.

http://www.bmj.com/cgi/eletters/319/7220/1312/b#5406


USA PRION UNIT BLOG

http://prionunitusaupdate2008.blogspot.com/



Sunday, April 20, 2008

Progress Report from the National Prion Disease Pathology Surveillance Center April 3, 2008

Atypical forms of BSE have emerged which, although rare, appear to be more virulent than the classical BSE that causes vCJD.

see full text ;

http://prionunitusaupdate2008.blogspot.com/2008/04/progress-report-from-national-prion.html



Tuesday, August 03, 2010

Variably protease-sensitive prionopathy: A new sporadic disease of the prion protein

http://creutzfeldt-jakob-disease.blogspot.com/2010/08/variably-protease-sensitive-prionopathy.html



Monday, August 9, 2010

Variably protease-sensitive prionopathy: A new sporadic disease of the prion protein or just more PRIONBALONEY ?

http://prionunitusaupdate2008.blogspot.com/2010/08/variably-protease-sensitive-prionopathy.html



***+++***

Thursday, July 10, 2008

A Novel Human Disease with Abnormal Prion Protein Sensitive to Protease update July 10, 2008 Friday, June 20, 2008

http://cjdmadcowbaseoct2007.blogspot.com/2008/07/novel-human-disease-with-abnormal-prion.html



Monday, August 9, 2010

National Prion Disease Pathology Surveillance Center Cases Examined (July 31, 2010)

(please watch and listen to the video and the scientist speaking about atypical BSE and sporadic CJD and listen to Professor Aguzzi)

http://prionunitusaupdate2008.blogspot.com/2010/08/national-prion-disease-pathology.html



CJD TEXAS (cjd clusters)

http://cjdtexas.blogspot.com/



THE PATHOLOGICAL PROTEIN

Hardcover, 304 pages plus photos and illustrations. ISBN 0-387-95508-9

June 2003

BY Philip Yam

CHAPTER 14 LAYING ODDS

Answering critics like Terry Singeltary, who feels that the U.S. under- counts CJD, Schonberger conceded that the current surveillance system has errors but stated that most of the errors will be confined to the older population.

http://www.thepathologicalprotein.com/


The statistical incidence of CJD cases in the United States has been revised to reflect that there is one case per 9000 in adults age 55 and older. Eighty-five percent of the cases are sporadic, meaning there is no known cause at present.

http://www.cjdfoundation.org/fact.html


USA WRITTEN CJD QUESTIONNAIRE ???

http://cjdquestionnaire.blogspot.com/



P.S.

Technical Abstract:

Prion strains may vary in their ability to transmit to humans and animals. Few experimental studies have been done to provide evidence of differences between U.S. strains of scrapie, which can be distinguished by incubation times in inbred mice, microscopic lesions, immunoreactivity to various antibodies, or molecular profile (electrophoretic mobility and glycoform ratio). Recent work on two U.S. isolates of sheep scrapie supports that at least two distinct strains exist based on differences in incubation time and genotype of sheep affected. One isolate (No. 13-7) inoculated intracerebrally caused scrapie in sheep AA at codon 136 (AA136) and QQ at codon 171 (QQ171) of the prion protein in an average of 19 months post-inoculation (PI) whereas a second isolate (No. x124) caused disease in less than 12 months after oral inoculation in AV136/QQ171 sheep. Striking differences were evident when further strain analysis was done in R111, VM, C57Bl6, and C57Bl6xVM (F1) mice. No. 13-7 did not induce disease in any mouse strain at any time post-inoculation (PI) nor were brain tissues positive by western blot (WB). Positive WB results were obtained from mice inoculated with isolate No. x124 starting at day 380 PI. Incubation times averaged 508, 559, 601, and 633 days PI for RIII, C57Bl6, VM, and F1 mice, respectively. Further passage will be required to characterize these scrapie strains in mice. This work provides evidence that multiple scrapie strains exist in U.S. sheep.

http://www.ars.usda.gov/research/publications/publications.htm?seq_no_115=227516


One of these isolates (TR316211) behaved like the CH1641 isolate, with PrPres features in mice similar to those in the sheep brain. From two other isolates (O100 and O104), two distinct PrPres phenotypes were identified in mouse brains, with either high (h-type) or low (l-type) apparent molecular masses of unglycosylated PrPres, the latter being similar to that observed with CH1641, TR316211, or BSE. Both phenotypes could be found in variable proportions in the brains of the individual mice. In contrast with BSE, l-type PrPres from "CH1641-like" isolates showed lower levels of diglycosylated PrPres. From one of these cases (O104), a second passage in mice was performed for two mice with distinct PrPres profiles. This showed a partial selection of the l-type phenotype in mice infected with a mouse brain with predominant l-type PrPres, and it was accompanied by a significant increase in the proportions of the diglycosylated band. These results are discussed in relation to the diversity of scrapie and BSE strains.


http://jvi.asm.org/cgi/content/full/81/13/7230?view=long&pmid=17442721


In the US, scrapie is reported primarily in sheep homozygous for 136A/171Q (AAQQ) and the disease phenotype is similar to that seen with experimental strain CH1641.

http://www.ars.usda.gov/research/publications/publications.htm?seq_no_115=182469


BSE: TIME TO TAKE H.B. PARRY SERIOUSLY

If the scrapie agent is generated from ovine DNA and thence causes disease in other species, then perhaps, bearing in mind the possible role of scrapie in CJD of humans (Davinpour et al, 1985), scrapie and not BSE should be the notifiable disease. ...

http://collections.europarchive.org/tna/20090505194948/http://bseinquiry.gov.uk/files/yb/1988/06/08004001.pdf



Friday, February 04, 2011

NMLB and USDA allow scrapie prion infected mutton to enter food chain on the Navajo Reservation in New Mexico

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

From: Terry S. Singeltary Sr.

To: President.BenShelly

Cc: sroanhorse ; opvp.nelson ; alaughing; georgehardeen; pressoffice

Sent: Thursday, February 03, 2011 12:15 PM

Subject: NMLB and USDA allow scrapie prion infected mutton to enter food chain on the Navajo Reservation in New Mexico

Greetings Honorable People of the Great Navajo Nation, and the Honorable President Ben Shelly,

I send this to you with great concern. ...

http://scrapie-usa.blogspot.com/2011/02/nmlb-and-usda-allow-scrapie-prion.html



http://transmissiblespongiformencephalopathy.blogspot.com//





Friday, February 11, 2011

Atypical/Nor98 Scrapie Infectivity in Sheep Peripheral Tissues


http://nor-98.blogspot.com/2011/02/atypicalnor98-scrapie-infectivity-in.html








Terry S. Singeltary Sr.
P.O. Box 42
Bacliff, Texas USA 77518