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Arnold M, Ru G, Simmons M, Vidal‐Diez A, Ortiz‐Pelaez A, Stella P. Scientific report on the analysis of the 2-year compulsory intensified monitoring of atypical scrapie. EFSA J 2021; 19:e06686. [PMID: 34262626 PMCID: PMC8265166 DOI: 10.2903/j.efsa.2021.6686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The European Commission asked EFSA whether the scientific data on the 2-year intensified monitoring in atypical scrapie (AS) outbreaks (2013-2020) provide any evidence on the contagiousness of AS, and whether they added any new knowledge on the epidemiology of AS. An ad hoc data set from intensified monitoring in 22 countries with index case/s of AS in sheep and/or goats (742 flocks from 20 countries, 76 herds from 11 countries) was analysed. No secondary cases were confirmed in goat herds, while 35 secondary cases were confirmed in 28 sheep flocks from eight countries. The results of the calculated design prevalence and of a model simulation indicated that the intensified monitoring had limited ability to detect AS, with no difference between countries with or without secondary cases. A regression model showed an increased, but not statistically significant, prevalence (adjusted by surveillance stream) of secondary cases in infected flocks compared with that of index cases in the non-infected flocks (general population). A simulation model of within-flock transmission, comparing a contagious (i.e. transmissible between animals under natural conditions) with a non-contagious scenario, produced a better fit of the observed data with the non-contagious scenario, in which each sheep in a flock had the same probability of developing AS in the first year of life. Based on the analyses performed, and considering uncertainties and data limitations, it was concluded that there is no new evidence that AS can be transmitted between animals under natural conditions, and it is considered more likely (subjective probability range 50-66%) that AS is a non-contagious, rather than a contagious disease. The analysis of the data of the EU intensified monitoring in atypical scrapie infected flocks/herds confirmed some of the known epidemiological features of AS but identified that major knowledge gaps still remain.
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Konold T, Spiropoulos J, Thorne J, Phelan L, Fothergill L, Rajanayagam B, Floyd T, Vidana B, Charnley J, Coates N, Simmons M. The Scrapie Prevalence in a Goat Herd Is Underestimated by Using a Rapid Diagnostic Test. Front Bioeng Biotechnol 2020; 8:164. [PMID: 32226784 PMCID: PMC7081731 DOI: 10.3389/fbioe.2020.00164] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 02/18/2020] [Indexed: 11/30/2022] Open
Abstract
Current European surveillance regulations for scrapie, a naturally occurring transmissible spongiform encephalopathy (TSE) or prion disease in sheep and goats, require testing of fallen stock or healthy slaughter animals, and outline measures in the case of confirmation of disease. An outbreak of classical scrapie in a herd with 2500 goats led to the culling of the whole herd, providing the opportunity to examine a subset of goats, take samples, and examine them for the presence of disease-associated prion protein (PrPSc) to provide further information on scrapie test sensitivity, pathology, and association with prion protein genotype. Goats were examined clinically prior to cull, and the brains examined post mortem by Bio-Rad ELISA, a rapid screening test used for active surveillance in sheep and goats, and two confirmatory tests, Western blot and immunohistochemistry. Furthermore, up to 10 lymphoid tissues were examined by immunohistochemistry. Of 151 goats examined, three (2.0%) tested positive for scrapie by ELISA on brain, confirmed by confirmatory tests, and a further five (3.3%) were negative by ELISA but positive by at least one of the confirmatory tests. Only two of these, both positive by ELISA, displayed evident signs of scrapie. In addition, 10 (6.6%) goats, which also included two clinical suspects, were negative on brain examination but had detectable PrPSc in lymphoid tissue. PrPSc was detected most frequently in the medial retropharyngeal lymph node (LN; 94.4% of all 18 cases) and palatine tonsil (88.9%). Abnormal behavior and circling or loss of balance when blindfolded were the best clinical discriminators for scrapie status. None of the goats that carried a single allele in the prion protein gene associated with increased resistance to scrapie (Q211, K222, S146) were scrapie-positive, and the percentage of goats with these alleles was greater than expected from previous surveys. Significantly more goats that were scrapie-positive were isoleucine homozygous at codon 142 (II142). The results indicate that the sensitivity of the applied screening test is poor in goats compared to the confirmatory tests as gold standard, particularly for asymptomatic animals. Sensitivity of surveillance could be improved by testing retropharyngeal LN or palatine tonsil in addition to brain.
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Affiliation(s)
- Timm Konold
- Pathology Department, Animal and Plant Health Agency Weybridge, Addlestone, United Kingdom
| | - John Spiropoulos
- Pathology Department, Animal and Plant Health Agency Weybridge, Addlestone, United Kingdom
| | - Jemma Thorne
- Pathology Department, Animal and Plant Health Agency Weybridge, Addlestone, United Kingdom
| | - Laura Phelan
- Pathology Department, Animal and Plant Health Agency Weybridge, Addlestone, United Kingdom
| | - Louise Fothergill
- Central Sequencing Unit, Animal and Plant Health Agency Weybridge, Addlestone, United Kingdom
| | - Brenda Rajanayagam
- Department of Epidemiological Sciences, Animal and Plant Health Agency Weybridge, Addlestone, United Kingdom
| | - Tobias Floyd
- Pathology Department, Animal and Plant Health Agency Weybridge, Addlestone, United Kingdom
| | - Beatriz Vidana
- Pathology Department, Animal and Plant Health Agency Weybridge, Addlestone, United Kingdom
| | - Judith Charnley
- Animal and Plant Health England Field Delivery, Skipton, United Kingdom
| | - Nadya Coates
- TSE/BVDV Testing Laboratory, Eurofins Forensic Services, Risley, United Kingdom
| | - Marion Simmons
- Pathology Department, Animal and Plant Health Agency Weybridge, Addlestone, United Kingdom
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Pei F, DiSalvo S, Sindi SS, Serio TR. A dominant-negative mutant inhibits multiple prion variants through a common mechanism. PLoS Genet 2017; 13:e1007085. [PMID: 29084237 PMCID: PMC5679637 DOI: 10.1371/journal.pgen.1007085] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 11/09/2017] [Accepted: 10/20/2017] [Indexed: 11/18/2022] Open
Abstract
Prions adopt alternative, self-replicating protein conformations and thereby determine novel phenotypes that are often irreversible. Nevertheless, dominant-negative prion mutants can revert phenotypes associated with some conformations. These observations suggest that, while intervention is possible, distinct inhibitors must be developed to overcome the conformational plasticity of prions. To understand the basis of this specificity, we determined the impact of the G58D mutant of the Sup35 prion on three of its conformational variants, which form amyloids in S. cerevisiae. G58D had been previously proposed to have unique effects on these variants, but our studies suggest a common mechanism. All variants, including those reported to be resistant, are inhibited by G58D but at distinct doses. G58D lowers the kinetic stability of the associated amyloid, enhancing its fragmentation by molecular chaperones, promoting Sup35 resolubilization, and leading to amyloid clearance particularly in daughter cells. Reducing the availability or activity of the chaperone Hsp104, even transiently, reverses curing. Thus, the specificity of inhibition is determined by the sensitivity of variants to the mutant dosage rather than mode of action, challenging the view that a unique inhibitor must be developed to combat each variant.
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Affiliation(s)
- Fen Pei
- The University of Arizona, Department of Molecular and Cellular Biology, Tucson, Arizona, United States of America
| | - Susanne DiSalvo
- Brown University, Department of Molecular and Cell Biology, Providence, Rhode Island, United States of America
| | - Suzanne S. Sindi
- University of California, Merced, Applied Mathematics, School of Natural Sciences, Merced, California, United States of America
- * E-mail: (SS); (TRS)
| | - Tricia R. Serio
- The University of Arizona, Department of Molecular and Cellular Biology, Tucson, Arizona, United States of America
- * E-mail: (SS); (TRS)
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Abstract
Dietary exposure to Bovine Spongiform Encephalopathy (BSE) contaminated bovine tissues is considered as the origin of variant Creutzfeldt-Jakob disease (vCJD) in humans. 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 modelling of the "species barrier," the biological phenomenon that limits TSE agents' propagation from one species to another. In the past decade, mice genetically engineered to express normal forms of the human prion protein have proven to be essential in studying human prions pathogenesis and modelling 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 goats to a greater degree than the BSE agent in cattle, and that these agents can convey molecular properties and be neuropathologically 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.
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Imamura M, Miyazawa K, Iwamaru Y, Matsuura Y, Yokoyama T, Okada H. Identification of the first case of atypical scrapie in Japan. J Vet Med Sci 2016; 78:1915-1919. [PMID: 27616556 PMCID: PMC5240776 DOI: 10.1292/jvms.16-0379] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A Corriedale ewe was confirmed as the first atypical scrapie case during an active surveillance program for transmissible spongiform encephalopathies in small ruminants in Japan. The animal was homozygous for the AF141RQ haplotype of PRNP. The animal showed clinical neurological signs possibly due to listeriosis before culling. Western blot analysis showed an unusual multiple banded pattern with a low-molecular fragment at ~7 kDa. Histopathology revealed suppurative meningoencephalitis caused by listeriosis in the brainstem. Fine granular to globular immunostaining of disease-associated prion proteins was mainly detected in the neuropil of the spinal tract of the trigeminal nerve and in the white matter of the spinocerebellar tract. Based on these results, this case was conclusively diagnosed as atypical scrapie with encephalitic listeriosis.
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Affiliation(s)
- Morikazu Imamura
- National Institute of Animal Health, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki 305-0856, Japan
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Okada H, Miyazawa K, Imamura M, Iwamaru Y, Masujin K, Matsuura Y, Yokoyama T. Transmission of atypical scrapie to homozygous ARQ sheep. J Vet Med Sci 2016; 78:1619-1624. [PMID: 27320968 PMCID: PMC5095634 DOI: 10.1292/jvms.16-0259] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Two Cheviot ewes homozygous for the A136L141R154Q171 (AL141RQ) prion protein (PrP) genotype were exposed intracerebrally to brain pools prepared using four field cases of atypical scrapie from the United Kingdom. Animals were clinically normal until the end of the experiment, when they were culled 7 years post-inoculation. Limited accumulation of disease-associated PrP (PrPSc) was observed in the cerebellar molecular layer by immunohistochemistry, but not by western blot or enzyme-linked immunosorbent assay. In addition, PrPSc was partially localized in astrocytes and microglia, suggesting that these cells have a role in PrPSc processing, degradation or both. Our results indicate that atypical scrapie is transmissible to AL141RQ sheep, but these animals act as clinically silent carriers with long incubation times.
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Affiliation(s)
- Hiroyuki Okada
- National Institute of Animal Health, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki 305-0856, Japan
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Epidemiological investigations on the potential transmissibility of a rare disease: the case of atypical scrapie in Great Britain. Epidemiol Infect 2016; 144:2107-16. [PMID: 26976340 DOI: 10.1017/s0950268816000303] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Multiple cases of atypical scrapie in the same holding and co-existence with classical scrapie have been reported in Great Britain. A two-stage simulation tool was developed by combining a sampling algorithm and a hierarchical Bayesian model to simulate the number of positive cases of atypical scrapie from: (i) random sampling and (ii) using the actual sampled population in Great Britain, being the output probability of detection of flocks with one and more cases. Cluster analysis was conducted to assess the level of geographical over- and under-sampling over the years. The probability of detecting at least two cases of atypical scrapie in the same holding is much lower in simulated random data than in simulated actual data for all scenarios. Sampling bias in the selection of sheep for testing led to multiple sampling from fewer but larger holdings, Scotland, and areas of Wales were under-sampled and the South-West and East of England oversampled. The pattern of atypical scrapie cases observed is unlikely to be explained by a multi-case event epidemiologically linked. The co-existence of classical and atypical scrapie is a rare event with 19 holdings detected in GB and does not suggest an epidemiological link between the two types of disease.
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Simmons MM, Moore SJ, Lockey R, Chaplin MJ, Konold T, Vickery C, Spiropoulos J. Phenotype shift from atypical scrapie to CH1641 following experimental transmission in sheep. PLoS One 2015; 10:e0117063. [PMID: 25710519 PMCID: PMC4339189 DOI: 10.1371/journal.pone.0117063] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 12/18/2014] [Indexed: 11/19/2022] Open
Abstract
The interactions of host and infecting strain in ovine transmissible spongiform encephalopathies are known to be complex, and have a profound effect on the resulting phenotype of disease. In contrast to classical scrapie, the pathology in naturally-occurring cases of atypical scrapie appears more consistent, regardless of genotype, and is preserved on transmission within sheep homologous for the prion protein (PRNP) gene. However, the stability of transmissible spongiform encephalopathy phenotypes on passage across and within species is not absolute, and there are reports in the literature where experimental transmissions of particular isolates have resulted in a phenotype consistent with a different strain. In this study, intracerebral inoculation of atypical scrapie between two genotypes both associated with susceptibility to atypical forms of disease resulted in one sheep displaying an altered phenotype with clinical, pathological, biochemical and murine bioassay characteristics all consistent with the classical scrapie strain CH1641, and distinct from the atypical scrapie donor, while the second sheep did not succumb to challenge. One of two sheep orally challenged with the same inoculum developed atypical scrapie indistinguishable from the donor. This study adds to the range of transmissible spongiform encephalopathy phenotype changes that have been reported following various different experimental donor-recipient combinations. While these circumstances may not arise through natural exposure to disease in the field, there is the potential for iatrogenic exposure should current disease surveillance and feed controls be relaxed. Future sheep to sheep transmission of atypical scrapie might lead to instances of disease with an alternative phenotype and onward transmission potential which may have adverse implications for both public health and animal disease control policies.
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Affiliation(s)
- Marion M. Simmons
- Animal and Plant Health Agency—Weybridge, Woodham Lane, Addlestone, Surrey, KT15 3NB, United Kingdom
- * E-mail:
| | - S. Jo Moore
- Animal and Plant Health Agency—Weybridge, Woodham Lane, Addlestone, Surrey, KT15 3NB, United Kingdom
| | - Richard Lockey
- Animal and Plant Health Agency—Weybridge, Woodham Lane, Addlestone, Surrey, KT15 3NB, United Kingdom
| | - Melanie J Chaplin
- Animal and Plant Health Agency—Weybridge, Woodham Lane, Addlestone, Surrey, KT15 3NB, United Kingdom
| | - Timm Konold
- Animal and Plant Health Agency—Weybridge, Woodham Lane, Addlestone, Surrey, KT15 3NB, United Kingdom
| | - Christopher Vickery
- Animal and Plant Health Agency—Weybridge, Woodham Lane, Addlestone, Surrey, KT15 3NB, United Kingdom
| | - John Spiropoulos
- Animal and Plant Health Agency—Weybridge, Woodham Lane, Addlestone, Surrey, KT15 3NB, United Kingdom
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Prion protein misfolding, strains, and neurotoxicity: an update from studies on Mammalian prions. Int J Cell Biol 2013; 2013:910314. [PMID: 24454379 PMCID: PMC3884631 DOI: 10.1155/2013/910314] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2013] [Revised: 11/10/2013] [Accepted: 11/11/2013] [Indexed: 11/17/2022] Open
Abstract
Prion diseases, also known as transmissible spongiform encephalopathies (TSEs), are a group of fatal neurodegenerative disorders affecting humans and other mammalian species. The central event in TSE pathogenesis is the conformational conversion of the cellular prion protein, PrPC, into the aggregate, β-sheet rich, amyloidogenic form, PrPSc. Increasing evidence indicates that distinct PrPSc conformers, forming distinct ordered aggregates, can encipher the phenotypic TSE variants related to prion strains. Prion strains are TSE isolates that, after inoculation into syngenic hosts, cause disease with distinct characteristics, such as incubation period, pattern of PrPSc distribution, and regional severity of histopathological changes in the brain. In analogy with other amyloid forming proteins, PrPSc toxicity is thought to derive from the existence of various intermediate structures prior to the amyloid fiber formation and/or their specific interaction with membranes. The latter appears particularly relevant for the pathogenesis of TSEs associated with GPI-anchored PrPSc, which involves major cellular membrane distortions in neurons. In this review, we update the current knowledge on the molecular mechanisms underlying three fundamental aspects of the basic biology of prions such as the putative mechanism of prion protein conversion to the pathogenic form PrPSc and its propagation, the molecular basis of prion strains, and the mechanism of induced neurotoxicity by PrPSc aggregates.
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Meydan H, Özkan MM, Yildiz MA. Genetic risk assessment for atypical scrapie in Turkish native sheep breeds. Small Rumin Res 2013. [DOI: 10.1016/j.smallrumres.2012.08.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Taema MM, Maddison BC, Thorne L, Bishop K, Owen J, Hunter N, Baker CA, Terry LA, Gough KC. Differentiating ovine BSE from CH1641 scrapie by serial protein misfolding cyclic amplification. Mol Biotechnol 2012; 51:233-9. [PMID: 21987099 DOI: 10.1007/s12033-011-9460-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Whilst ovine BSE displays distinct pathological characteristics to ovine CH1641-like scrapie upon passage in rodents, they have very similar molecular phenotypes. As such, the in vitro differentiation of these strains in routine surveillance programmes presents a significant diagnostic challenge. In this study, using serial protein-misfolding cyclic amplification (sPMCA), ovine BSE was readily amplified in vitro in brain substrates from sheep with V₁₃₆R₁₅₄Q₁₇₁/V₁₃₆R₁₅₄Q₁₇₁ or AHQ/AHQ PRNP genotypes. In contrast, the CH1641 strain was refractory to such amplification. This method allowed for complete and unequivocal differentiation of experimental BSE from CH1641 prion strains within an ovine host.
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Affiliation(s)
- Maged M Taema
- School of Veterinary Medicine and Science, The University of Nottingham, Sutton Bonington Campus, College Road, Sutton Bonington, Leicestershire LE12 5RD, UK
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Sarasa R, Martínez A, Monleón E, Bolea R, Vargas A, Badiola JJ, Monzón M. Involvement of astrocytes in transmissible spongiform encephalopathies: a confocal microscopy study. Cell Tissue Res 2012; 350:127-34. [PMID: 22821398 DOI: 10.1007/s00441-012-1461-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 05/31/2012] [Indexed: 02/02/2023]
Abstract
Astroglial proliferation associated with pathological prion protein (PrPsc) deposition is widely described in Transmissible Spongiform Encephalopathies (TSEs). However, little is known of the actual role played by glia in their pathogenesis. The aim of the study has been to determine whether PrPsc is located exclusively in neurons or in both neurons and glial cells present in the central nervous system in a natural Scrapie model. Samples of cerebellum from 25 Scrapie sheep from various flocks were sectioned. Following epitope retrieval with formic acid, proteinase K and heat treatment, primary antibody L42 and primary antibodies against glial fibrillary acidic protein were applied as prion- and astrocytic-specific markers, respectively. For visualization, a suitable mixture of fluorochrome-conjugated secondary antibodies was used. Relevant controls were processed in the same manner. As determined by confocal microscopy, PrPsc deposits co-localized with glial cells in all samples. Our results suggest that these cells can sustain active prion propagation, in agreement with similar findings from other studies of primary cell cultures and inoculated mice. Furthermore, despite ongoing debate regarding whether varied TSE sources show differences in their tropism for different cell lineages in the brains of affected animals, no differences in co-localization results were seen.
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Affiliation(s)
- Rocío Sarasa
- Research Centre for Encephalopathies and Transmissible Emerging Diseases, University of Zaragoza, C/ Miguel Servet 177, 50013 Zaragoza, Spain
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Wemheuer WM, Benestad SL, Wrede A, Wemheuer WE, Brenig B, Bratberg B, Schulz-Schaeffer WJ. PrPSc spreading patterns in the brain of sheep linked to different prion types. Vet Res 2011; 42:32. [PMID: 21324114 PMCID: PMC3050706 DOI: 10.1186/1297-9716-42-32] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 02/15/2011] [Indexed: 11/17/2022] Open
Abstract
Scrapie in sheep and goats has been known for more than 250 years and belongs nowadays to the so-called prion diseases that also include e.g. bovine spongiform encephalopathy in cattle (BSE) and Creutzfeldt-Jakob disease in humans. According to the prion hypothesis, the pathological isoform (PrPSc) of the cellular prion protein (PrPc) comprises the essential, if not exclusive, component of the transmissible agent. Currently, two types of scrapie disease are known - classical and atypical/Nor98 scrapie. In the present study we examine 24 cases of classical and 25 cases of atypical/Nor98 scrapie with the sensitive PET blot method and validate the results with conventional immunohistochemistry. The sequential detection of PrPSc aggregates in the CNS of classical scrapie sheep implies that after neuroinvasion a spread from spinal cord and obex to the cerebellum, diencephalon and frontal cortex via the rostral brainstem takes place. We categorize the spread of PrPSc into four stages: the CNS entry stage, the brainstem stage, the cruciate sulcus stage and finally the basal ganglia stage. Such a sequential development of PrPSc was not detectable upon analysis of the present atypical/Nor98 scrapie cases. PrPSc distribution in one case of atypical/Nor98 scrapie in a presumably early disease phase suggests that the spread of PrPSc aggregates starts in the di- or telencephalon. In addition to the spontaneous generation of PrPSc, an uptake of the infectious agent into the brain, that bypasses the brainstem and starts its accumulation in the thalamus, needs to be taken into consideration for atypical/Nor98 scrapie.
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Affiliation(s)
- Wiebke M Wemheuer
- Prion and Dementia Research Unit, Department of Neuropathology, University Medical Center, Georg-August University, Robert-Koch Str, 40, 37075 Goettingen, Germany.
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Seuberlich T, Heim D, Zurbriggen A. Atypical transmissible spongiform encephalopathies in ruminants: a challenge for disease surveillance and control. J Vet Diagn Invest 2011; 22:823-42. [PMID: 21088166 DOI: 10.1177/104063871002200601] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Since 1987, when bovine spongiform encephalopathy (BSE) emerged as a novel disease in cattle, enormous efforts were undertaken to monitor and control the disease in ruminants worldwide. The driving force was its high economic impact, which resulted from trade restrictions and the loss of consumer confidence in beef products, the latter because BSE turned out to be a fatal zoonosis, causing variant Creutzfeldt-Jakob disease in human beings. The ban on meat and bone meal in livestock feed and the removal of specified risk materials from the food chain were the main measures to successfully prevent infection in cattle and to protect human beings from BSE exposure. However, although BSE is now under control, previously unknown, so-called atypical transmissible spongiform encephalopathies (TSEs) in cattle and small ruminants have been identified by enhanced disease surveillance. This report briefly reviews and summarizes the current level of knowledge on the spectrum of TSEs in cattle and small ruminants and addresses the question of the extent to which such atypical TSEs have an effect on disease surveillance and control strategies.
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Affiliation(s)
- Torsten Seuberlich
- NeuroCentre, National and OIE Reference Laboratories for BSE and Scrapie, DCR-VPH, Bremgartenstrasse 109a, CH-3001 Berne, Switzerland.
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Marie McIntyre K, Del Rio Vilas VJ, Gubbins S. Demographic characteristics of scrapie-affected holdings identified by active and passive surveillance schemes in Great Britain: 2002–2005. Vet J 2011; 187:207-11. [DOI: 10.1016/j.tvjl.2009.12.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Revised: 11/18/2009] [Accepted: 12/05/2009] [Indexed: 10/20/2022]
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Abstract
Although prion diseases, such as Creutzfeldt-Jakob disease (CJD) in humans and scrapie in sheep, have long been recognized, our understanding of their epidemiology and pathogenesis is still in its early stages. Progress is hampered by the lengthy incubation periods and the lack of effective ways of monitoring and characterizing these agents. Protease-resistant conformers of the prion protein (PrP), known as the "scrapie form" (PrP(Sc)), are used as disease markers, and for taxonomic purposes, in correlation with clinical, pathological, and genetic data. In humans, prion diseases can arise sporadically (sCJD) or genetically (gCJD and others), caused by mutations in the PrP-gene (PRNP), or as a foodborne infection, with the agent of bovine spongiform encephalopathy (BSE) causing variant CJD (vCJD). Person-to-person spread of human prion disease has only been known to occur following cannibalism (kuru disease in Papua New Guinea) or through medical or surgical treatment (iatrogenic CJD, iCJD). In contrast, scrapie in small ruminants and chronic wasting disease (CWD) in cervids behave as infectious diseases within these species. Recently, however, so-called atypical forms of prion diseases have been discovered in sheep (atypical/Nor98 scrapie) and in cattle, BSE-H and BSE-L. These maladies resemble sporadic or genetic human prion diseases and might be their animal equivalents. This hypothesis also raises the significant public health question of possible epidemiological links between these diseases and their counterparts in humans.
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Loiacono CM, Beckwith N, Kunkle RA, Orcutt D, Hall SM. Detection of PrP(Sc) in formalin-fixed, paraffin-embedded tissue by Western blot differentiates classical scrapie, Nor98 scrapie, and bovine spongiform encephalopathy. J Vet Diagn Invest 2010; 22:684-9. [PMID: 20807921 DOI: 10.1177/104063871002200502] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Transmissible, spongiform encephalopathies including bovine spongiform encephalopathy (BSE) and scrapie are fatal neurodegenerative disorders associated with the presence of an infectious abnormal isoform of normal mammalian proteins called prions. Identification of the prion protein associated with scrapie (PrP(Sc)) in the central nervous system is typically based upon immunoassays including immunohistochemistry (IHC) using formalin-fixed tissues or Western blot (WB) assays using fresh and/or frozen, non-formalin-fixed tissues. Each assay can discriminate between BSE, classical scrapie, and a previously reported strain of scrapie recently identified in the United States named Nor98 scrapie. Different tissue samples are required from the same animal to run these 2 different immunoassays. This may result in inconsistent test results for the same animal. Sampling problems such as collecting insufficient volumes of fresh tissue or less than optimal anatomic location of brainstem for IHC can affect the ability of the test procedures to offer definitive and discriminatory results. Recently, a WB method using formalin-fixed, paraffin-embedded (FFPE) tissue to identify PrP(Sc) was developed that successfully identified PrP(Sc) in sheep affected by classical scrapie. In the current study, the use of this technique to produce discriminatory results identifying classical BSE in bovine tissue and both classical and Nor98 scrapie in ovine tissue using paraffin-embedded brain samples is described. Protein-banding patterns from WB using FFPE tissue were similar to protein-banding patterns produced by WB assays utilizing fresh tissues from the same animals, and results correlated well with the IHC PrP(Sc)-positive staining present in the cerebellum and obex regions of brain samples from these animals.
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Affiliation(s)
- Christina M Loiacono
- Animal and Plant Health Inspection Services, National Veterinary Services Laboratories, Pathobiology Laboratory, U.S. Department of Agriculture, Ames, IA 50010, USA.
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Rodríguez-Martínez AB, Garrido JM, Maza S, Benedicto L, Geijo M, Gómez N, Minguijón E, Benestad SL, Juste RA. Atypical/Nor98 scrapie in the Basque Country: a case report of eight outbreaks. BMC Vet Res 2010; 6:17. [PMID: 20346155 PMCID: PMC2859363 DOI: 10.1186/1746-6148-6-17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Accepted: 03/26/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Since 2002, an active surveillance program for transmissible spongiform encephalopathy in small ruminants in European Union countries allowed identification of a considerable number of atypical cases with similarities to the previously identified atypical scrapie cases termed Nor98. CASE PRESENTATION Here we report molecular and neuropathological features of eight atypical/Nor98 scrapie cases detected between 2002 and 2009. Significant features of the affected sheep included: their relatively high ages (mean age 7.9 years, range between 4.3 and 12.8), their breed (all Latxa) and their PRNP genotypes (AFRQ/ALRQ, ALRR/ALRQ, AFRQ/AFRQ, AFRQ/AHQ, ALRQ/ALRH, ALRQ/ALRQ). All the sheep were confirmed as atypical scrapie by immunohistochemistry and immunoblotting. Two cases presented more PrP immunolabelling in cerebral cortex than in cerebellum. CONCLUSIONS This work indicates that atypical scrapie constitutes the most common small ruminant transmissible spongiform encephalopathy form in Latxa sheep in the Spanish Basque Country. Moreover, a new genotype (ALRQ/ALRH) was found associated to atypical scrapie.
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Affiliation(s)
| | - Joseba M Garrido
- Department of Animal Health. Neiker-Tecnalia, 48160 Derio. Bizkaia. Spain
| | - Sonia Maza
- Department of Animal Health. Neiker-Tecnalia, 48160 Derio. Bizkaia. Spain
| | - Leyre Benedicto
- Department of Animal Health. Neiker-Tecnalia, 48160 Derio. Bizkaia. Spain
| | - Mariví Geijo
- Department of Animal Health. Neiker-Tecnalia, 48160 Derio. Bizkaia. Spain
| | - Nieves Gómez
- Department of Animal Health. Neiker-Tecnalia, 48160 Derio. Bizkaia. Spain
| | | | - Sylvie L Benestad
- National Veterinary Institute, Department of Pathology, Postboks 750 Sentrum. 0106 Oslo. Norway
| | - Ramón A Juste
- Department of Animal Health. Neiker-Tecnalia, 48160 Derio. Bizkaia. Spain
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Simmons MM, Konold T, Thurston L, Bellworthy SJ, Chaplin MJ, Moore SJ. The natural atypical scrapie phenotype is preserved on experimental transmission and sub-passage in PRNP homologous sheep. BMC Vet Res 2010; 6:14. [PMID: 20219126 PMCID: PMC2848638 DOI: 10.1186/1746-6148-6-14] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2009] [Accepted: 03/10/2010] [Indexed: 11/26/2022] Open
Abstract
Background Atypical scrapie was first identified in Norwegian sheep in 1998 and has subsequently been identified in many countries. 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. The first 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.
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Affiliation(s)
- Marion M Simmons
- Department of Pathology, Veterinary Laboratories Agency Weybridge, New Haw, Addlestone KT15 3NB, UK.
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21
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Orge L, Oliveira A, Machado C, Lima C, Ochoa C, Silva J, Carvalho R, Tavares P, Almeida P, Ramos M, Pinto MJ, Simas JP. Putative emergence of classical scrapie in a background of enzootic atypical scrapie. J Gen Virol 2010; 91:1646-50. [PMID: 20164262 DOI: 10.1099/vir.0.018879-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Active transmissible spongiform encephalopathy (TSE) surveillance in small ruminants across Europe was implemented in 2002 following the epizootic of bovine spongiform encephalopathy. Here, we report the potential emergence of classical scrapie in Portugal, in a background of enzootic atypical scrapie. Between 2003 and 2008, 375,459 small ruminants were screened in total, with 328 animals confirmed positive for NOR98 atypical scrapie. During this period, the prevalence rate of atypical scrapie for all years combined was 0.0874% across the country. In this scenario, classical scrapie emerged as a single outbreak in 2008, with 12 identified cases. In contrast to other European countries, where classical scrapie has been enzootic for decades, these data indicate that, in Portugal, atypical scrapie is the predominant form of TSE. The findings reported here will have implications for the control of classical scrapie in Portugal, namely in terms of keeping the country free of enzootic classical scrapie.
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Affiliation(s)
- Leonor Orge
- Laboratório Nacional de Investigação Veterinária, Instituto Nacional de Recursos Biológicos, I. P., Portugal
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22
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Fediaevsky A, Maurella C, Nöremark M, Ingravalle F, Thorgeirsdottir S, Orge L, Poizat R, Hautaniemi M, Liam B, Calavas D, Ru G, Hopp P. The prevalence of atypical scrapie in sheep from positive flocks is not higher than in the general sheep population in 11 European countries. BMC Vet Res 2010; 6:9. [PMID: 20137097 PMCID: PMC2832631 DOI: 10.1186/1746-6148-6-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Accepted: 02/07/2010] [Indexed: 11/10/2022] Open
Abstract
Background During the last decade, active surveillance for transmissible spongiform encephalopathies in small ruminants has been intensive in Europe. In many countries this has led to the detection of cases of atypical scrapie which, unlike classical scrapie, might not be contagious. EU legislation requires, that following detection of a scrapie case, control measures including further testing take place in affected flocks, including the culling of genotype susceptible to classical scrapie. This might result in the detection of additional cases. The aim of this study was to investigate the occurrence of additional cases in flocks affected by atypical scrapie using surveillance data collected in Europe in order to ascertain whether atypical scrapie, is contagious. Results Questionnaires were used to collect, at national level, the results of active surveillance and testing associated with flock outbreaks in 12 European countries. The mean prevalence of atypical scrapie was 5.5 (5.0-6.0) cases per ten thousand in abattoir surveillance and 8.1 (7.3-9.0) cases per ten thousand in fallen stock. By using meta-analysis, on 11 out of the 12 countries, we found that the probability of detecting additional cases of atypical scrapie in positive flocks was similar to the probability observed in animals slaughtered for human consumption (odds ratio, OR = 1.07, CI95%: 0.70-1.63) or among fallen stock (OR = 0.78, CI95%: 0.51-1.2). In contrast, when comparing the two scrapie types, the probability of detecting additional cases in classical scrapie positive flocks was significantly higher than the probability of detecting additional cases in atypical scrapie positive flocks (OR = 32.4, CI95%: 20.7-50.7). Conclusions These results suggest that atypical scrapie is not contagious or has a very low transmissibility under natural conditions compared with classical scrapie. Furthermore this study stressed the importance of standardised data collection to make good use of the analyses undertaken by European countries in their efforts to control atypical and classical scrapie.
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Affiliation(s)
- Alexandre Fediaevsky
- Section of epidemiology, National Veterinary Institute, PO Box 750 Sentrum, 0106 Oslo, Norway
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23
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Scientific Opinion on Risk of transmission of TSEs via semen and embryo transfer in small ruminants (sheep and goats). EFSA J 2010. [DOI: 10.2903/j.efsa.2010.1429] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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24
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Co-existence of classical scrapie and Nor98 in a sheep from an Italian outbreak. Res Vet Sci 2009; 88:478-85. [PMID: 20031179 DOI: 10.1016/j.rvsc.2009.11.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 11/23/2009] [Accepted: 11/25/2009] [Indexed: 11/22/2022]
Abstract
Nor98 is an atypical scrapie strain characterized by a molecular pattern and brain distribution of the pathological prion protein (PrP(Sc)) different from classical scrapie. In Italy, 69 atypical cases have been identified so far and all were characterized as Nor98 strain. In this paper we report an unusual case in a sheep which showed immunohistochemical and molecular features of PrP(Sc) different from the other atypical cases. The sheep was from an outbreak where the index and the other four cases were affected by classical scrapie. Histopathological, immunohistochemical and Western blot analyses on the brain of the unusual case revealed the simultaneous presence of pathological features characteristic of Nor98 and classical scrapie. Interestingly, the prevalent disease phenotype in the brainstem was classical scrapie-like, while in the cerebral cortex and cerebellum the Nor98 phenotype was dominant. The sub-mandibular lymph node was positive and showed a PrP(Sc) molecular pattern referable to classical scrapie. The PrP genotype was AL(141)RQ/AF(141)RQ. Taken together, the occurrence of classical scrapie in the outbreak, the PrP genotype, the involvement of different cellular targets in the brain and the pathological and molecular PrP(Sc) features observed suggest that this unusual case may result from the co-existence of Nor98 and classical scrapie.
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25
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Loiacono CM, Thomsen BV, Hall SM, Kiupel M, Sutton D, O'Rourke K, Barr B, Anthenill L, Keane D. Nor98 scrapie identified in the United States. J Vet Diagn Invest 2009; 21:454-63. [PMID: 19564493 DOI: 10.1177/104063870902100406] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
A distinct strain of scrapie identified in sheep of Norway in 1998 has since been identified in numerous countries throughout Europe. The disease is known as Nor98 or Nor98-like scrapie, among other names. Distinctions between classic scrapie and Nor98 scrapie are made based on histopathology and immunodiagnostic results. There are also differences in the epidemiology, typical signalment, and likelihood of clinical signs being observed. In addition, sheep that have genotypes associated with resistance to classic scrapie are not spared from Nor98 disease. The various differences between classic and Nor98 scrapie have been consistently reported in the vast majority of cases described across Europe. The current study describes in detail the pathologic changes and diagnostic results of the first 6 cases of Nor98 scrapie disease diagnosed in sheep of the United States.
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26
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Polak MP, Larska M, Langeveld JPM, Buschmann A, Groschup MH, Zmudzinski JF. Diagnosis of the first cases of scrapie in Poland. Vet J 2009; 186:47-52. [PMID: 19716323 DOI: 10.1016/j.tvjl.2009.07.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Revised: 07/13/2009] [Accepted: 07/28/2009] [Indexed: 12/01/2022]
Abstract
This is the first report of cases of scrapie in Poland. The disease was an atypical phenotype, diagnosed in two aged sheep which were found dead. Brainstem samples from both animals were positive on the applied ELISA rapid test, while the confirmatory immunoblot indicated abnormal banding patterns of protease resistant prion protein (PrP(res)). The genotypes of these sheep were ALRQ/ALHQ and ALRQ/ALRR. The absence of premonitory clinical signs, the advanced age of the affected sheep, the higher concentration of PrP(res) in the cerebellum relative to the obex, the unusual banding profile of the prion protein and its relatively low resistance to proteolytic degradation confirmed the diagnosis of atypical scrapie (Nor98-like) in both cases.
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Affiliation(s)
- Miroslaw P Polak
- National Veterinary Research Institute, Partyzantow 57, 24-100 Pulawy, Poland.
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27
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Wemheuer WM, Benestad SL, Wrede A, Wemheuer WE, Brenig B, Bratberg B, Schulz-Schaeffer WJ. Detection of classical and atypical/Nor98 scrapie by the paraffin-embedded tissue blot method. Vet Rec 2009; 164:677-81. [PMID: 19483208 DOI: 10.1136/vr.164.22.677] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
The paraffin-embedded tissue (PET) blot method was used to investigate sections of the central nervous system and lymphatic tissues from 24 cases of classical scrapie and 25 cases of atypical/Nor98 scrapie in sheep and four healthy control sheep. The PET blot detected deposits of PrP(Sc) in the brain tissue of all 49 sheep with scrapie but no PrP(Sc) labelling could be detected in the control sheep. By contrast, not all the atypical/Nor98 scrapie cases were detectable by immunohistochemistry. The high sensitivity of the PET blot method made it possible to observe that in some atypical/Nor98 cases, deposits of PrP(Sc) may be restricted to supratentorial brain structures and that the diagnosis may be missed when only testing the obex area, where deposits are common in classical scrapie, and the cerebellar structures, where deposits are considered to be common in atypical/Nor98 cases.
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Affiliation(s)
- W M Wemheuer
- Prion and Dementia Research Unit, Department of Neuropathology, University Medical Centre, Göttingen, 37075 Göttingen, Germany
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28
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Laude H, Béringue V. [Newly discovered forms of prion diseases in ruminants]. PATHOLOGIE-BIOLOGIE 2009; 57:117-126. [PMID: 18848406 DOI: 10.1016/j.patbio.2008.07.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Accepted: 07/03/2008] [Indexed: 05/26/2023]
Abstract
Transmissible spongiform encephalopathies (TSEs), are fatal neurodegenerative diseases caused by unconventional agents, the prions. They are characterised by the accumulation in infected tissues of an abnormally folded form of the host-encoded prion protein (PrP). This pathological form is partially resistant to protease digestion, leading to the production of so-called PrP(res) fragments. Different isolates from the same host species may show different eletrophoretic profiles, reflecting the existence of different prion strains. The active surveillance of ruminant TSEs implemented in European countries, based on a large-scale biochemical testing of brain tissue samples from carcasses, has revealed PrP(res) profiles unnoticed so far. Experimental transmission of these atypical cases to various transgenic mouse lines has led to the recognition of a novel scrapie strain in sheep and goats, called Nor98, and of two variant strains of spongiform encephalopathy in cattle. This review is aimed at summarising the current knowledge on these newly recognised forms of ruminants TSEs, and at discussing their possible origin and potential implications in terms of animal and human health.
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Affiliation(s)
- H Laude
- INRA, U892, virologie immunologie moléculaires, domaine de Vilvert, 78350 Jouy-en-Josas, France.
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29
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Human and animal exposure risk related to Transmissible Spongiform Encephalopathies (TSEs) from milk and milk products derived from small ruminants Scientific opinion of the Panel on Biological Hazards. EFSA J 2008. [DOI: 10.2903/j.efsa.2008.849] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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30
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Neuroanatomical distribution of abnormal prion protein in naturally occurring atypical scrapie cases in Great Britain. Acta Neuropathol 2008; 116:547-59. [PMID: 18797889 DOI: 10.1007/s00401-008-0433-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Revised: 09/01/2008] [Accepted: 09/01/2008] [Indexed: 10/21/2022]
Abstract
Scrapie belongs to a group of diseases known as the transmissible spongiform encephalopathies or prion diseases. Two different categories of naturally occurring scrapie have been identified: classical scrapie, which was first recorded around 1750, and atypical scrapie or 'Nor-98', which was first identified in Norway in 1998. The molecular characteristics of atypical scrapie have been well defined, but detailed descriptions of the neuropathological phenotype are rare since the majority of cases have been detected through active surveillance programmes where only brainstem and cerebellum are collected for statutory diagnosis. In order to characterise the neuropathology of naturally occurring atypical scrapie in sheep, we examined multiple brain levels from 15 whole brains from field cases of atypical scrapie, both clinical suspects and fallen stock, collected in Great Britain between 2004 and 2006. We found that the distribution of disease-associated prion protein (PrP(Sc)) and vacuolation in atypical scrapie cases are very different to both classical scrapie and experimental bovine spongiform encephalopathy in sheep. Immunolabelling for PrP(Sc) is mild and restricted at the obex and more intense and widespread rostrally, particularly in the cerebellum, substantia nigra, thalamus and basal nuclei. Intracellular immunolabelling types are not seen, but distinctive white matter immunolabelling is widespread. Vacuolation associated with PrP(Sc) deposits was not observed in the brainstem neuroanatomical areas commonly affected in classical scrapie and bovine spongiform encephalopathy, but was instead most prominent in the cerebellar cortex and neocortex. This is the largest comprehensive descriptive study of atypical scrapie pathology to date, and provides baseline data against which other natural or experimental cases can be compared. It also reinforces the current recommendation to collect cerebellum in addition to brainstem to enable confident confirmation of this distinct disease phenotype within surveillance programmes.
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31
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Genotyping of the prion protein (PrP) gene in Red Maasai and Black Head Persian sheep in Tanzania. Small Rumin Res 2008. [DOI: 10.1016/j.smallrumres.2008.07.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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32
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Fediaevsky A, Tongue SC, Nöremark M, Calavas D, Ru G, Hopp P. A descriptive study of the prevalence of atypical and classical scrapie in sheep in 20 European countries. BMC Vet Res 2008; 4:19. [PMID: 18544152 PMCID: PMC2442063 DOI: 10.1186/1746-6148-4-19] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2008] [Accepted: 06/10/2008] [Indexed: 12/03/2022] Open
Abstract
Background The development of active surveillance programmes for transmissible spongiform encephalopathies of small ruminants across Europe has led to the recent identification of a previously undetected form of ovine prion disease, 'atypical' scrapie. Knowledge of the epidemiology of this disease is still limited, as is whether it represents a risk for animal and/or public health. The detection of atypical scrapie has been related to the use of only some of the EU agreed rapid tests. Information about the rapid tests used is not, as yet, available from public reports on the surveillance of transmissible spongiform encephalopathies in small ruminants. We collected detailed results of active surveillance from European countries to estimate and to compare the prevalence of atypical scrapie and classical scrapie in sheep for each country stratified by each surveillance stream; healthy slaughtered and found dead adult sheep. Results From the 20 participating countries, it appeared that atypical scrapie was detected in Europe wherever the conditions necessary for its diagnosis were present. In most countries, atypical scrapie and classical scrapie occurred at low prevalence level. The classical scrapie prevalence estimates were more variable than those for atypical scrapie, which appeared remarkably homogeneous across countries, surveillance streams and calendar years of surveillance. Differences were observed in the age and genotype of atypical scrapie and classical scrapie cases that are consistent with previous published findings. Conclusion This work suggests that atypical scrapie is not rare compared to classical scrapie. The homogeneity of its prevalence, whatever the country, stream of surveillance or year of detection, contrasts with the epidemiological pattern of classical scrapie. This suggests that the aetiology of atypical scrapie differs from that of classical scrapie.
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Affiliation(s)
- Alexandre Fediaevsky
- AFSSA-Lyon, Unité Epidémiologie, 31 Avenue Tony Garnier, 69364 Lyon Cedex 07, France.
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33
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Fésüs L, Zsolnai A, Anton I, Sáfár L. Breeding for scrapie resistance in the Hungarian sheep population. Acta Vet Hung 2008; 56:173-80. [PMID: 18669244 DOI: 10.1556/avet.56.2008.2.4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The first results of the Hungarian sheep prion protein (PrP) genotyping programme are discussed in this paper. To obtain initial genotype frequency data 10 commercial (Hungarian Merino, German Mutton Merino, Merino Landschaf, German Blackheaded, Suffolk, Texel, Ile de France, Charollais, Lacaune, British Milksheep) and 4 indigenous (Gyimes Racka, Hortobágy Racka, Tsigaja, Cikta) breeds were sampled in 2003 and 2004, and the PrP genotypes were determined by microsequencing analysis with capillary electrophoresis. In all commercial breeds, a higher number of sheep were genotyped in 2005 (3648) and in 2006 (3834) within the breeding programme to increase scrapie resistance, and the estimated frequency data were compared to the initial figures to evaluate the efficiency of selection. The new developments arising from the identification of the so-called 'atypical' scrapie cases are also discussed.
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Affiliation(s)
- László Fésüs
- 1 Research Institute for Animal Breeding and Nutrition H-2053 Herceghalom, Gesztenyés út 1 Hungary
| | - Attila Zsolnai
- 1 Research Institute for Animal Breeding and Nutrition H-2053 Herceghalom, Gesztenyés út 1 Hungary
| | - István Anton
- 1 Research Institute for Animal Breeding and Nutrition H-2053 Herceghalom, Gesztenyés út 1 Hungary
| | - László Sáfár
- 2 Hungarian Sheepbreeders’ Association Budapest Hungary
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34
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Foster J, Toovey L, McKenzie C, Chong A, Parnham D, Drummond D, Hunter N. Atypical scrapie in a sheep in a closed uk
flock with endemic classical natural scrapie. Vet Rec 2008; 162:723-4. [PMID: 18515761 DOI: 10.1136/vr.162.22.723] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- J. Foster
- Roslin Institute; Neuropathogenesis Unit; Ogston Building, West Mains Road Edinburgh EH9 3JF
| | - L. Toovey
- Roslin Institute; Neuropathogenesis Unit; Ogston Building, West Mains Road Edinburgh EH9 3JF
| | - C. McKenzie
- Roslin Institute; Neuropathogenesis Unit; Ogston Building, West Mains Road Edinburgh EH9 3JF
| | - A. Chong
- Roslin Institute; Neuropathogenesis Unit; Ogston Building, West Mains Road Edinburgh EH9 3JF
| | - D. Parnham
- Roslin Institute; Neuropathogenesis Unit; Ogston Building, West Mains Road Edinburgh EH9 3JF
| | - D. Drummond
- Roslin Institute; Neuropathogenesis Unit; Ogston Building, West Mains Road Edinburgh EH9 3JF
| | - N. Hunter
- Roslin Institute; Neuropathogenesis Unit; Ogston Building, West Mains Road Edinburgh EH9 3JF
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35
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Dagleish MP, Rodger SM, Simmons MM, Finlayson J, Buxton D, Chianini F. Atypical scrapie in a sheep in Scotland. Vet Rec 2008; 162:518-9. [DOI: 10.1136/vr.162.16.518] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- M. P. Dagleish
- Moredun Research Institute; Pentlands Science Park, Bush Loan Penicuik Midlothian EH26 0PZ
| | - S. M. Rodger
- Moredun Research Institute; Pentlands Science Park, Bush Loan Penicuik Midlothian EH26 0PZ
| | - M. M. Simmons
- Veterinary Laboratories Agency - Weybridge; Woodham Lane, New Haw Addlestone Surrey KT15 3NB
| | - J. Finlayson
- Moredun Research Institute; Pentlands Science Park, Bush Loan Penicuik Midlothian EH26 0PZ
| | - D. Buxton
- Moredun Research Institute; Pentlands Science Park, Bush Loan Penicuik Midlothian EH26 0PZ
| | - F. Chianini
- Moredun Research Institute; Pentlands Science Park, Bush Loan Penicuik Midlothian EH26 0PZ
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36
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McIntyre KM, del Rio Vilas VJ, Gubbins S. No temporal trends in the prevalence of atypical scrapie in British sheep, 2002-2006. BMC Vet Res 2008; 4:13. [PMID: 18384678 PMCID: PMC2397389 DOI: 10.1186/1746-6148-4-13] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Accepted: 04/02/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND So-called atypical scrapie was first identified in Great Britain (GB) in 2002 following the introduction of wide-scale scrapie surveillance. In particular, abattoir and fallen stock surveys have been carried out in GB since 2002, with a total of 147 atypical positives identified by the end of 2006. The results of these surveys provide data with which to assess temporal trends in the prevalence of atypical scrapie in sheep in Great Britain between 2002 and 2006. RESULTS Using the results of abattoir and fallen stock surveys, the prevalence of atypical scrapie (percentage of samples positive) was estimated. The prevalence in the abattoir and fallen stock surveys, for all years combined, was 0.09% (95% confidence interval (CI): 0.08%-0.11%) and 0.07% (95% CI: 0.05%-0.11%), respectively. There were no significant temporal trends in either survey. Comparing the surveys' results, there were no significant differences in annual prevalence or the prevalence within PrP genotypes. For the abattoir survey, the PrP genotype with the highest prevalence was AHQ/AHQ, which was significantly higher than all other genotypes, except ARR/AHQ, AHQ/ARH and ARH/ARQ. CONCLUSION The estimated prevalence of atypical scrapie was similar in both the abattoir and fallen stock surveys. Our results indicate there was no significant temporal trend in prevalence, adding to evidence that this atypical form of scrapie may be a sporadic condition or, if it is infectious, that the force of infection is very low.
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Affiliation(s)
- K Marie McIntyre
- Institute for Animal Health, Pirbright Laboratory, Ash Road, Pirbright, Surrey GU24 0NF, UK.
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38
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Atypical PrPsc distribution in goats naturally affected with scrapie. J Comp Pathol 2008; 138:90-101. [PMID: 18295782 DOI: 10.1016/j.jcpa.2007.11.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2007] [Accepted: 11/06/2007] [Indexed: 11/24/2022]
Abstract
The brain and spinal cord of 48 goats from two Greek herds in which scrapie had been reported were examined. All animals were symptomless at the time of euthanasia. Notably, no lesions were observed either at the level of the obex or at other regions of the brain and spinal cord. Immunohistochemical examination revealed PrPsc labelling of the linear and fine punctuate types, mainly in the cerebral cortices, of 36 goats. Twenty-seven of them were negative by ELISA (designed to detect proteinase-resistant PrP) at the level of the obex but positive in a pooled brain sample, and the majority carried PrP genotypes associated with scrapie susceptibility. Surprisingly, in 16 of the 27 animals, PrPsc deposits were detected only in the rostral parts of the brain. In addition, nine animals which were ELISA-positive at the level of the obex exhibited positive immunoreactivity, but not in the dorsal vagal nucleus. The findings indicate that this unusual scrapie type may have been underdiagnosed previously and may be of importance in scrapie surveillance programmes.
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39
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Benestad SL, Arsac JN, Goldmann W, Nöremark M. Atypical/Nor98 scrapie: properties of the agent, genetics, and epidemiology. Vet Res 2008; 39:19. [PMID: 18187032 DOI: 10.1051/vetres:2007056] [Citation(s) in RCA: 172] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Accepted: 10/23/2007] [Indexed: 11/14/2022] Open
Abstract
Atypical/Nor98 scrapie cases in sheep were diagnosed for the first time in Norway in 1998. They are now identified in small ruminants in most European countries and represent an increasingly large proportion of the scrapie cases diagnosed in Europe. Atypical/Nor98 scrapie isolates have shown to be experimentally transmissible into transgenic mice and sheep but the properties of the TSE agent involved, like its biological and biochemical features, are so clearly distinct from the agent involved in classical scrapie that they have provided a challenging diagnostic for many years. No strain diversity has yet been identified among the atypical/Nor98 scrapie sample cases. The genetic predisposition of the sheep affected by atypical/Nor98 scrapie is almost inverted compared to classical scrapie, and the exact origin of this sporadic TSE strain is still speculative, but a spontaneous, non-contagious origin, like sporadic Creutzfeldt-Jakob disease in humans, can not be excluded. Further transmission and epidemiological studies are needed to better address this hypothesis.
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40
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Seuberlich T, Botteron C, Benestad SL, Brünisholz H, Wyss R, Kihm U, Schwermer H, Friess M, Nicolier A, Heim D, Zurbriggen A. Atypical scrapie in a Swiss goat and implications for transmissible spongiform encephalopathy surveillance. J Vet Diagn Invest 2007; 19:2-8. [PMID: 17459826 DOI: 10.1177/104063870701900102] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Different types of transmissible spongiform encephalopathies (TSEs) affect sheep and goats. In addition to the classical form of scrapie, both species are susceptible to experimental infections with the bovine spongiform encephalopathy (BSE) agent, and in recent years atypical scrapie cases have been reported in sheep from different European countries. Atypical scrapie in sheep is characterized by distinct histopathologic lesions and molecular characteristics of the abnormal scrapie prion protein (PrP(sc)). Characteristics of atypical scrapie have not yet been described in detail in goats. A goat presenting features of atypical scrapie was identified in Switzerland. Although there was no difference between the molecular characteristics of PrP(sc) in this animal and those of atypical scrapie in sheep, differences in the distribution of histopathologic lesions and PrP(sc) deposition were observed. In particular the cerebellar cortex, a major site of PrP(sc) deposition in atypical scrapie in sheep, was found to be virtually unaffected in this goat. In contrast, severe lesions and PrP(sc) deposition were detected in more rostral brain structures, such as thalamus and midbrain. Two TSE screening tests and PrP(sc) immunohistochemistry were either negative or barely positive when applied to cerebellum and obex tissues, the target samples for TSE surveillance in sheep and goats. These findings suggest that such cases may have been missed in the past and could be overlooked in the future if sampling and testing procedures are not adapted. The epidemiological and veterinary public health implications of these atypical cases, however, are not yet known.
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Affiliation(s)
- Torsten Seuberlich
- NeuroCenter, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, Bremgartenstrasse 109a, CH-3001 Berne, Switzerland.
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41
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Nentwig A, Oevermann A, Heim D, Botteron C, Zellweger K, Drögemüller C, Zurbriggen A, Seuberlich T. Diversity in neuroanatomical distribution of abnormal prion protein in atypical scrapie. PLoS Pathog 2007; 3:e82. [PMID: 17559305 PMCID: PMC1891327 DOI: 10.1371/journal.ppat.0030082] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2007] [Accepted: 04/20/2007] [Indexed: 11/19/2022] Open
Abstract
Scrapie is a transmissible spongiform encephalopathy (TSE) in sheep and goats. In recent years, atypical scrapie cases were identified that differed from classical scrapie in the molecular characteristics of the disease-associated pathological prion protein (PrPsc). In this study, we analyze the molecular and neuropathological phenotype of nine Swiss TSE cases in sheep and goats. One sheep was identified as classical scrapie, whereas six sheep, as well as two goats, were classified as atypical scrapie. The latter revealed a uniform electrophoretic mobility pattern of the proteinase K–resistant core fragment of PrPsc distinct from classical scrapie regardless of the genotype, the species, and the neuroanatomical structure. Remarkably different types of neuroanatomical PrPsc distribution were observed in atypical scrapie cases by both western immunoblotting and immunohistochemistry. Our findings indicate that the biodiversity in atypical scrapie is larger than expected and thus impacts on current sampling and testing strategies in small ruminant TSE surveillance. In the view of concerns that bovine spongiform encephalopathy has entered the small ruminant population, comprehensive active surveillance programs for transmissible spongiform encephalopathies (TSEs) in sheep and goats were implemented worldwide. In these, previously unrecognized atypical scrapie cases were identified that to date represent the majority of detected small ruminant TSE cases in some countries. The pathogenesis and epidemiology of atypical scrapie, as well as its relevance to both animal health and food safety, is still poorly understood. In the present study, we performed a systematic neuropathological analysis of recently diagnosed atypical scrapie cases in Switzerland. Our results show that the neuropathological presentation in atypical scrapie–affected small ruminants varies remarkably, and the results indicate a biodiversity of TSEs in sheep and goats larger than expected, with some similarities to known human TSEs. These findings will form the basis for future research on TSE phenotypes and help to design experimental studies necessary to generate data for risk assessments and the implementation of appropriate disease-control strategies.
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Affiliation(s)
- Alice Nentwig
- NeuroCenter, Reference Laboratory for TSE in Animals, Vetsuisse Faculty, University of Berne, Berne, Switzerland
| | - Anna Oevermann
- NeuroCenter, Reference Laboratory for TSE in Animals, Vetsuisse Faculty, University of Berne, Berne, Switzerland
| | - Dagmar Heim
- Federal Veterinary Office, Liebefeld, Switzerland
| | - Catherine Botteron
- NeuroCenter, Reference Laboratory for TSE in Animals, Vetsuisse Faculty, University of Berne, Berne, Switzerland
| | - Karola Zellweger
- NeuroCenter, Reference Laboratory for TSE in Animals, Vetsuisse Faculty, University of Berne, Berne, Switzerland
| | - Cord Drögemüller
- Institute of Genetics, Vetsuisse Faculty, University of Berne, Berne, Switzerland
| | - Andreas Zurbriggen
- NeuroCenter, Reference Laboratory for TSE in Animals, Vetsuisse Faculty, University of Berne, Berne, Switzerland
| | - Torsten Seuberlich
- NeuroCenter, Reference Laboratory for TSE in Animals, Vetsuisse Faculty, University of Berne, Berne, Switzerland
- * To whom correspondence should be addressed. E-mail:
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Benkel BF, Valle E, Bissonnette N, Hossain Farid A. Simultaneous detection of eight single nucleotide polymorphisms in the ovine prion protein gene. Mol Cell Probes 2007; 21:363-7. [PMID: 17590312 DOI: 10.1016/j.mcp.2007.05.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2007] [Revised: 04/23/2007] [Accepted: 05/01/2007] [Indexed: 10/23/2022]
Abstract
Amino acid polymorphisms in the prion protein gene (PrP) affect the susceptibility of sheep to scrapie, a transmissible spongiform encephalopathy (TSE). In particular, amino acid substitutions at codons 136, 154 and 171 of the ovine PrP gene are associated with different degrees of susceptibility to the classical form of scrapie, caused by 'typical' scrapie strains. Existing genotyping tests for scrapie susceptibility normally interrogate only the single nucleotide polymorphisms (SNPs) most relevant to 'typical' strains. Recently, however, a number of novel variants of the scrapie agent have been discovered. The ability of these new, 'atypical' scrapie variants to infect sheep that are resistant to 'typical' variants has raised concerns about the reduction in genetic variability that may result from intense selection for resistance to classical scrapie. Furthermore, a growing interest in a potential role for specific PrP genotypes in modulating performance traits is also driving a move toward more extensive characterization of haplotypes at the PrP locus. Here, we describe a single-tube method for the interrogation of eight SNPs within seven codons (112, 136, 141, 154, 171, 231 and 241) of the ovine PrP gene. This method is as accurate as sequencing, yet more affordable, and can easily be automated for high-throughput sample screening. Moreover, it can be modified to accommodate genetic variations that are found in local and heritage breeds.
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Affiliation(s)
- Bernhard F Benkel
- Department of Plant and Animal Sciences, Nova Scotia Agricultural College, Truro, NS, Canada B2N 5E3.
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43
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Spiropoulos J, Casalone C, Caramelli M, Simmons MM. Immunohistochemistry for PrPSc in natural scrapie reveals patterns which are associated with the PrP genotype. Neuropathol Appl Neurobiol 2007; 33:398-409. [PMID: 17617872 DOI: 10.1111/j.1365-2990.2007.00800.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Immunohistochemistry for PrPSc is used widely in scrapie diagnosis. In natural scrapie cases the use of immunohistochemistry (IHC) has revealed the existence of up to 12 different morphological types of immunostained deposits. The significance of this pattern variability in relation to genotype has not been studied extensively in natural disease. In this study we recorded in detail PrPSc patterns at the obex level of the medulla oblongata from 163 animals derived from 55 flocks which presented through passive surveillance in the UK and Italy. A strong association was seen between PrPSc patterns and PrP genotype, particularly in relation to codon 136. In a blind assessment of this association we were able to predict, with over 80% accuracy, the genotype of 151 scrapie cases which were presented through passive surveillance from 13 farms. The genotype of these cases was ARQ/ARQ or VRQ/VRQ. The association of PrPsc patterns with genotype was generally stronger in those farms where all the affected animals belonged to a single genotype compared with farms where both genotypes were identified, with the exception of one farm in which the genotype of all affected sheep was ARQ/ARQ and the PrPSc patterns were of the VRQ/VRQ type. Our observations support the hypothesis that the observed association between specific IHC patterns and genotypes may in fact be strain driven but in natural disease individual scrapie strains may demonstrate a genotypic tropism.
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Affiliation(s)
- J Spiropoulos
- Neuropathology Unit, Veterinary Laboratories Agency, Weybridge, Surrey, UK.
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44
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Simmons MM, Konold T, Simmons HA, Spencer YI, Lockey R, Spiropoulos J, Everitt S, Clifford D. Experimental transmission of atypical scrapie to sheep. BMC Vet Res 2007; 3:20. [PMID: 17725818 PMCID: PMC2025597 DOI: 10.1186/1746-6148-3-20] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2007] [Accepted: 08/28/2007] [Indexed: 12/04/2022] Open
Abstract
Background Active surveillance for transmissible spongiform encephalopathies in small ruminants has been an EU regulatory requirement since 2002. A number of European countries have subsequently reported cases of atypical scrapie, similar to previously published cases from Norway, which have pathological and molecular features distinct from classical scrapie. Most cases have occurred singly in flocks, associated with genotypes considered to be more resistant to classical disease. Experimental transmissibility of such isolates has been reported in certain ovinised transgenic mice, but has not previously been reported in the natural host. Information on the transmissibility of this agent is vital to ensuring that disease control measures are effective and proportionate. Results This report presents the successful experimental transmission, in 378 days, of atypical scrapie to a recipient sheep of homologous genotype with preservation of the pathological and molecular characteristics of the donor. This isolate also transmitted to ovinised transgenic mice (Tg338) with a murine phenotype indistinguishable from that of Nor 98. Conclusion This result strengthens the opinion that these cases result from a distinct strain of scrapie agent, which is potentially transmissible in the natural host under field conditions.
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Affiliation(s)
- Marion M Simmons
- Department of Pathology, Veterinary Laboratories Agency – Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - Timm Konold
- Department of Pathology, Veterinary Laboratories Agency – Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - Hugh A Simmons
- Animal Services Unit, Veterinary Laboratories Agency – Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - Yvonne I Spencer
- Department of Pathology, Veterinary Laboratories Agency – Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - Richard Lockey
- Department of Pathology, Veterinary Laboratories Agency – Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - John Spiropoulos
- Department of Pathology, Veterinary Laboratories Agency – Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - Sharon Everitt
- Department of Molecular Pathogenesis and Genetics, Veterinary Laboratories Agency – Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - Derek Clifford
- Animal Services Unit, Veterinary Laboratories Agency – Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK
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45
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Tongue SC, Wilesmith JW, Nash J, Kossaibati M, Ryan J. The importance of the PrP genotype in active surveillance for ovine scrapie. Epidemiol Infect 2007; 136:703-12. [PMID: 17588284 PMCID: PMC2870848 DOI: 10.1017/s0950268807008928] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Surveillance activities for ovine scrapie have expanded in the 21st century, following concerns about the potential for a hidden epidemic of bovine spongiform encephalopathy in European sheep populations. Large-scale surveys have been used to estimate the prevalence of scrapie infection. In this study we analyse data from the surveys in Great Britain between 2002 and 2004. When we estimate genotype-specific prevalences for each of the two screening tests used a difference is observed. One test underestimates the number of positive cases in genotypes classically considered to be at a low relative risk of developing clinical disease (ARR- and AHQ-containing genotypes). By comparison, the other test underestimates the number of positive cases in genotypes classically considered to be at an increased relative risk of developing clinical disease (VRQ-containing genotypes). These findings have implications for surveillance, disease control, and diagnostic test evaluation.
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Affiliation(s)
- S C Tongue
- Centre for Epidemiology and Risk Analysis, Veterinary Laboratories Agency, Weybridge, Surrey, UK.
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46
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Vidal E, Tortosa R, Costa C, Benavides J, Francino O, Sánchez-Robert E, Pérez V, Pumarola M. Lack of PrP(sc) immunostaining in intracranial ectopic lymphoid follicles in a sheep with concomitant non-suppurative encephalitis and Nor98-like atypical scrapie: a case report. Vet J 2007; 177:283-8. [PMID: 17574883 DOI: 10.1016/j.tvjl.2007.04.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2007] [Revised: 03/09/2007] [Accepted: 04/04/2007] [Indexed: 11/19/2022]
Abstract
During active surveillance for transmissible spongiform encephalopathies (TSEs) in sheep, an initial reactor was detected using a rapid test on a brain sample. Immunohistochemistry confirmed an atypical TSE presentation that closely resembled the previously described Nor98 cases. Sequencing of the prnp gene confirmed the ARQ/AHQ genotype with the L141F mutation at codon 141 associated with this phenotype. The head, including the brain and cranial lymphoid tissues, was sampled and examined thoroughly. Non-purulent encephalitis, with ectopic lymphoid follicle formation within the brain, was diagnosed concomitant to the TSE. When scrapie-associated prion protein (PrP(sc)) deposition was studied by immunohistochemistry there was a noticeable lack of lymphotropism. The distribution of PrP(sc) in the brain differed considerably from that of classical scrapie cases. Astrogliosis and microgliosis were demonstrated by histochemical procedures.
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Affiliation(s)
- E Vidal
- Priocat Laboratory, CReSA, Autonomous University of Barcelona, Bellaterra (Cerdanyola del Vallès), Spain
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47
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Arsac JN, Andreoletti O, Bilheude JM, Lacroux C, Benestad SL, Baron T. Similar biochemical signatures and prion protein genotypes in atypical scrapie and Nor98 cases, France and Norway. Emerg Infect Dis 2007; 13:58-65. [PMID: 17370516 PMCID: PMC2725815 DOI: 10.3201/eid1301.060393] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Similarities raise questions regarding the origin of these recently described cases. Isolates of atypical scrapie recently identified in sheep and goats in France were compared with Nor98 isolates reported in Norway. Western blot methods for characterization of the protease-resistant prion protein showed that all these isolates shared a unique biochemical signature: 5 groups of bands, including a characteristic band of apparent low molecular weight (11 kDa). This pattern could originate from the presence of 3 different protease cleavage products, including the 11 kDa most likely cleaved at both N- and C-sides of the protein. Genetic data, which strongly suggested the higher susceptibility of AHQ and AF141RQ animals in French cases, resembled earlier data from Nor98 scrapie.
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Affiliation(s)
- Jean-Noël Arsac
- Agence Française de Sécurité Sanitaire des Aliments, Lyon, France
| | | | | | | | | | - Thierry Baron
- Agence Française de Sécurité Sanitaire des Aliments, Lyon, France
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Abstract
Scrapie is the longest known and most widely spread of the transmissible spongiform encephalopathies and remains the model for much of the research regarding these diseases. Because scrapie is a reportable disease and the subject of an active eradication program in the United States, veterinary practitioners should have a basic understanding of the disease.
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Affiliation(s)
- Marie S Bulgin
- Department of Animal and Veterinary Science, Caine Veterinary Teaching Center, University of Idaho, Caldwell, ID 83607, USA
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49
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Konold T, Davis A, Bone G, Bracegirdle J, Everitt S, Chaplin M, Saunders GC, Cawthraw S, Simmons MM. Clinical findings in two cases of atypical scrapie in sheep: a case report. BMC Vet Res 2007; 3:2. [PMID: 17298670 PMCID: PMC1810526 DOI: 10.1186/1746-6148-3-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2006] [Accepted: 02/13/2007] [Indexed: 12/03/2022] Open
Abstract
Background Atypical scrapie is a recently recognised form of transmissible spongiform encephalopathy of sheep that differs from classical scrapie in its neuropathological and biochemical features. Most cases are detected in apparently healthy sheep and information on the clinical presentation is limited. Case presentation This report describes the clinical findings in two sheep notified as scrapie suspects and confirmed as atypical scrapie cases by immunohistochemistry and Western immunoblotting. Although both sheep displayed signs suggestive of a cerebellar dysfunction there was considerable variation in the individual clinical signs, which were similar to classical scrapie. Conclusion Any sheep presenting with neurological gait deficits should be assessed more closely for other behavioural, neurological and physical signs associated with scrapie and their presence should lead to the suspicion of scrapie.
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Affiliation(s)
- Timm Konold
- Neuropathology, Veterinary Laboratories Agency Weybridge, New Haw, Addlestone, UK
- Royal Veterinary College, Population Biology and Disease Control Research Group, North Mymms, Hatfield, UK
| | - Andrew Davis
- Neuropathology, Veterinary Laboratories Agency Weybridge, New Haw, Addlestone, UK
| | - Gemma Bone
- Neuropathology, Veterinary Laboratories Agency Weybridge, New Haw, Addlestone, UK
| | | | - Sharon Everitt
- TSE Molecular Biology 4, Veterinary Laboratories Agency Weybridge, New Haw, Addlestone, UK
| | - Melanie Chaplin
- TSE Molecular Biology 4, Veterinary Laboratories Agency Weybridge, New Haw, Addlestone, UK
| | - Ginny C Saunders
- TSE Molecular Biology 4, Veterinary Laboratories Agency Weybridge, New Haw, Addlestone, UK
| | - Saira Cawthraw
- TSE Molecular Biology 4, Veterinary Laboratories Agency Weybridge, New Haw, Addlestone, UK
| | - Marion M Simmons
- Neuropathology, Veterinary Laboratories Agency Weybridge, New Haw, Addlestone, UK
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Corbière F, Barillet F, Andréoletti O, Fidelle F, Laphitz-Bordet N, Schelcher F, Joly P. Advanced survival models for risk-factor analysis in scrapie. J Gen Virol 2007; 88:696-705. [PMID: 17251589 DOI: 10.1099/vir.0.81981-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Because of the confounding effects of long incubation duration and flock management, accurate epidemiological studies of scrapie outbreaks are difficult to carry out. In this study, 641 Manech red-faced sheep from six scrapie-affected field flocks in Pyrénées Atlantiques, France, were monitored for clinical scrapie over a 6–9 year period. Over this period, 170 scrapie clinical cases were recorded and half of the culled animals were submitted for post-mortem transmissible spongiform encephalopathy diagnosis to assess their infectious status. Collected data were analysed using a ‘mixture cure model’ approach, which allowed for the discriminating effect of PrP genotype and flock origin on incidence and incubation period. Simulations were performed to evaluate the applicability of such a statistical model to the collected data. As expected, ARR heterozygote sheep were less at risk of becoming infected than ARQ/ARQ individuals and had a greater age at clinical onset. Conversely, when compared with ARQ/ARQ, the VRQ haplotype was associated with an increased infection risk, but not a shorter incubation period. Considering the flock effect, we observed that a high incidence rate was not associated with shorter incubation periods and that the incubation period could be significantly different in flocks harbouring similar infection risks. These results strongly support the conclusion that other parameters, such as the nature of the agent or flock management, could interfere with epidemiological dynamics of the infection in scrapie-affected flocks.
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Affiliation(s)
- Fabien Corbière
- EMI 0338 (Biostatistique), Institut de Santé Publique et Développement, Université Victor Segalen Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France
- UMR Interactions Hôtes Agents Pathogènes, Ecole Nationale Vétérinaire de Toulouse, 23 chemin des Capelles, 31076 Toulouse Cedex, France
| | - Francis Barillet
- Station d'Amélioration des Animaux, Institut National de la Recherche Agronomique, BP 27, 31326 Castanet-Tolosan cedex, France
| | - Olivier Andréoletti
- UMR Interactions Hôtes Agents Pathogènes, Ecole Nationale Vétérinaire de Toulouse, 23 chemin des Capelles, 31076 Toulouse Cedex, France
| | - Francis Fidelle
- Centre Départemental d'Elevage Ovin, Quartier Ahetzia, 64130 Ordiarp, France
| | | | - François Schelcher
- UMR Interactions Hôtes Agents Pathogènes, Ecole Nationale Vétérinaire de Toulouse, 23 chemin des Capelles, 31076 Toulouse Cedex, France
| | - Pierre Joly
- EMI 0338 (Biostatistique), Institut de Santé Publique et Développement, Université Victor Segalen Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France
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