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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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Mathiason CK. Scrapie, CWD, and Transmissible Mink Encephalopathy. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2017; 150:267-292. [PMID: 28838664 DOI: 10.1016/bs.pmbts.2017.07.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Transmissible spongiform encephalopathies (TSEs), or prions, are neurodegenerative diseases that affect a variety of animal species, including humans. Cruetzfeldt-Jakob disease (CJD) in humans, sheep and goat scrapie, chronic wasting disease (CWD) of cervids, and transmissible mink encephalopathy (TME) of mink are classified as TSEs. According to the "protein-only" hypothesis (Prusiner, 1982),1 prions are devoid of nucleic acids and consist of assemblies of misfolded host-encoded normal protein, the prion protein (PrPC). Prion propagation is thought to occur by a templating mechanism during which PrPC is recruited, converted to a disease-associated isoform (PrPD), and assembled onto the growing amyloid fibril. This fibular assembly is infectious, with ability to initiate disease processes similar to other pathogenic agents. Evidence indicates that scrapie, CWD, and TME disease processes follow this rule.
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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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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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Chong A, Kennedy I, Goldmann W, Green A, González L, Jeffrey M, Hunter N. Archival search for historical atypical scrapie in sheep reveals evidence for mixed infections. J Gen Virol 2015; 96:3165-3178. [PMID: 26281831 DOI: 10.1099/jgv.0.000234] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Natural scrapie in sheep occurs in classical and atypical forms, which may be distinguished on the basis of the associated neuropathology and properties of the disease-associated prion protein on Western blots. First detected in 1998, atypical scrapie is known to have occurred in UK sheep since the 1980s. However, its aetiology remains unclear and it is often considered as a sporadic, non-contagious disease unlike classical scrapie which is naturally transmissible. Although atypical scrapie tends to occur in sheep of prion protein (PRNP) genotypes that are different from those found predominantly in classical scrapie, there is some overlap so that there are genotypes in which both scrapie forms can occur. In this search for early atypical scrapie cases, we made use of an archive of fixed and frozen sheep samples, from both scrapie-affected and healthy animals (∼1850 individuals), dating back to the 1960s. Using a selection process based primarily on PRNP genotyping, but also on contemporaneous records of unusual clinical signs or pathology, candidate sheep samples were screened by Western blot, immunohistochemistry and strain-typing methods using tg338 mice. We identified, from early time points in the archive, three atypical scrapie cases, including one sheep which died in 1972 and two which showed evidence of mixed infection with classical scrapie. Cases with both forms of scrapie in the same animal as recognizable entities suggest that mixed infections have been around for a long time and may potentially contribute to the variety of scrapie strains.
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Affiliation(s)
- Angela Chong
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - Iain Kennedy
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - Wilfred Goldmann
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - Andrew Green
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - Lorenzo González
- Animal and Plant Health Agency (APHA - Lasswade), Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK
| | - Martin Jeffrey
- Animal and Plant Health Agency (APHA - Lasswade), Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK
| | - Nora Hunter
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
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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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Dobly A, Van der Heyden S, Roels S. Trends in genotype frequency resulting from breeding for resistance to classical scrapie in Belgium (2006 ˜ 2011). J Vet Sci 2013; 14:45-51. [PMID: 23388443 PMCID: PMC3615231 DOI: 10.4142/jvs.2013.14.1.45] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 08/08/2012] [Indexed: 11/29/2022] Open
Abstract
In sheep, susceptibility to scrapie is mainly determined by codons 136, 154, and 171 of the PRNP gene. Five haplotypes are usually present (ARR, ARQ, ARH, AHQ, and VRQ). The ARR haplotype confers the greatest resistance to classical scrapie while VRQ renders animals most susceptible. In 2004, the European Union implemented a breeding program that promotes selection of the ARR haplotype while reducing the incidence of VRQ. From 2006 to 2011 in Belgium, frequency for the ARR/ARR genotypes increased from 38.3% to 63.8% (n = 6,437), the ARQ haplotype diminished from 21.1% to 12.9%, and the VRQ haplotype decreased from 2.0% to 1.7%. The status of codon 141, a determinant for atypical scrapie, was also evaluated. Out of 27 different breeds (n = 5,163), nine were abundant. The ARR/ARR frequency increased in eight of these nine major breeds. The selection program has had a major impact on the ARR haplotype frequency in Belgium. However, the occurrence of atypical scrapie represents a critical point for this program that warrants the continuous monitoring of scrapie. Additionally, genotype frequencies among the breeds varied greatly. Texel, a breed that is common in Belgium, can still be selected for due to its average ARR frequency.
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Affiliation(s)
- Alexandre Dobly
- Pathology and Prionology, Veterinary and Agrochemical Research Centre (CODA-CERVA), 1180 Brussels, Belgium
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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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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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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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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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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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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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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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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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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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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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22
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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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23
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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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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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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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27
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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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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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29
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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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30
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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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31
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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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Gretzschel A, Buschmann A, Langeveld J, Groschup MH. Immunological characterization of abnormal prion protein from atypical scrapie cases in sheep using a panel of monoclonal antibodies. J Gen Virol 2006; 87:3715-3722. [PMID: 17098989 DOI: 10.1099/vir.0.81816-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
After the implementation of an active surveillance programme for scrapie in sheep in the EU, the number of diagnosed classical scrapie cases rose sharply and a novel kind of so-called atypical scrapie case was discovered. These atypical scrapie cases display unusual features concerning the distribution of the abnormal prion protein (PrP(Sc)) in the brain, a distinct electrophoretic profile of PrP(Sc) and an inconsistent reaction pattern in the currently used rapid tests. In this report, PrP(Sc) of two German atypical sheep scrapie cases was characterized by epitope mapping using a panel of 18 monoclonal antibodies that were directed against epitopes located throughout the prion protein. This analysis suggests that PrP(Sc) derived from atypical scrapie cases and treated with proteinase K is largely composed of an 11 kDa fragment (previously referred to as the 12 kDa band) and of polymeric fragments thereof. The 11 kDa band corresponds to a prion protein fragment spanning approximately aa 90-153 and may therefore represent a novel PrP(Sc) type.
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Affiliation(s)
- Anja Gretzschel
- Institute for Novel and Emerging Infectious Diseases at the Friedrich-Loeffler-Institut, Boddenblick 5a, 17493 Greifswald-Insel Riems, Germany
| | - Anne Buschmann
- Institute for Novel and Emerging Infectious Diseases at the Friedrich-Loeffler-Institut, Boddenblick 5a, 17493 Greifswald-Insel Riems, Germany
| | - Jan Langeveld
- Central Institute for Animal Disease Control, PO Box 2004, 8203 AA Lelystad, The Netherlands
| | - Martin H Groschup
- Institute for Novel and Emerging Infectious Diseases at the Friedrich-Loeffler-Institut, Boddenblick 5a, 17493 Greifswald-Insel Riems, Germany
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Lühken G, Buschmann A, Brandt H, Eiden M, Groschup MH, Erhardt G. Epidemiological and genetical differences between classical and atypical scrapie cases. Vet Res 2006; 38:65-80. [PMID: 17156738 DOI: 10.1051/vetres:2006046] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Accepted: 09/13/2006] [Indexed: 11/15/2022] Open
Abstract
The aim of this study was to analyze the epidemiology and prion protein (PrP) genetics in scrapie-affected sheep flocks in Germany. For this purpose, 224 German scrapie cases in sheep diagnosed between January 2002 and February 2006 were classified as classical or atypical scrapie and the amino acids at codons 136, 141, 154 and 171 were determined. Likewise, representative numbers of flock mates were genotyped. Significant epidemiological differences were observed between classical and atypical scrapie cases in regard to the numbers of scrapie-affected sheep within a flock, the sizes of flocks with only a single scrapie-positive sheep or more than one scrapie-positive sheep and the age distribution of the scrapie-positive sheep. Sheep with the ARQ/ARQ genotype had by far the highest risk for acquiring classical scrapie, but the risk for atypical scrapie was the highest for sheep carrying phenylalanine (F) at position 141 (AF(141)RQ) and/or the AHQ haplotype. However, atypical scrapie also occurred with a notable frequency in sheep with the PrP haplotypes ARR and/or ARQ in combination with Leucine at position 141 (AL(141)RQ). Furthermore, six atypical scrapie-positive sheep carried the PrP genotype ARR/ARR. The high proportion of sheep flocks affected by atypical scrapie underscores the importance of this scrapie type.
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Affiliation(s)
- Gesine Lühken
- Department of Animal Breeding and Genetics, Justus-Liebig University of Giessen, 35390 Giessen, Germany.
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Abstract
Prions cause fatal and transmissible neurodegenerative disease. These etiological infectious agents are formed in greater part from a misfolded cell-surface protein called PrP(C). Several mammalian species are affected by the diseases, and in the case of "mad cow disease" (BSE) the agent has a tropism for humans, with negative consequences for agribusiness and public health. Unfortunately, the known universe of prion diseases is expanding. At least four novel prion diseases--including human diseases variant Creutzfeldt-Jakob disease (vCJD) and sporadic fatal insomnia (sFI), bovine amyloidotic spongiform encephalopathy (BASE), and Nor98 of sheep--have been identified in the last ten years, and chronic wasting disease (CWD) of North American deer (Odocoileus Specis) and Rocky Mountain elk (Cervus elaphus nelsoni) is undergoing a dramatic spread across North America. While amplification (BSE) and dissemination (CWD, commercial sourcing of cervids from the wild and movement of farmed elk) can be attributed to human activity, the origins of emergent prion diseases cannot always be laid at the door of humankind. Instead, the continued appearance of new outbreaks in the form of "sporadic" disease may be an inevitable outcome in a situation where the replicating pathogen is host-encoded.
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Affiliation(s)
- Joel C Watts
- Centre for Research in Neurodegenerative Diseases and Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.
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35
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Saunders GC, Cawthraw S, Mountjoy SJ, Hope J, Windl O. PrP genotypes of atypical scrapie cases in Great Britain. J Gen Virol 2006; 87:3141-3149. [PMID: 17030846 DOI: 10.1099/vir.0.81779-0] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Great Britain and elsewhere have detected atypical scrapie infection in sheep with PrP genotypes thought to be genetically resistant to the classical form of scrapie. DNA sequencing of the PrP gene of British atypical scrapie cases (n=69), classical scrapie cases (n=59) and scrapie-free controls (n=138) was undertaken to identify whether PrP variants, other than the three well-characterized polymorphic codons, influenced susceptibility to atypical scrapie infection. Four non-synonymous changes, M112T, M137T, L141F and P241S, were detected that are most probably associated with the A(136)R(154)Q(171) haplotype. Only the PrP variant containing a phenylalanine residue at amino acid position 141 was found to be associated more commonly with the atypical scrapie cases. In addition to the single nucleotide polymorphisms associated with the ARQ allele, two out of nine atypical scrapie cases with the ARR/ARR genotype were found to contain a 24 bp insertion, leading to an additional octapeptide repeat. In terms of PrP genetics, one classification of the GB scrapie cases examined in this study would place animals carrying any homozygous or heterozygous combination of ARR, AHQ or AF(141)RQ alleles, or any one of these alleles when paired with ARQ, as being susceptible to atypical scrapie infection, and animals heterozygous or homozygous for VRQ or homozygous for ARQ as being susceptible to classical scrapie disease. The AHQ PrP allele was associated with the highest incidence of atypical scrapie (263 per 100 000 alleles), whilst VRQ was associated with the lowest incidence (10 per 100 000 alleles).
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Affiliation(s)
- G C Saunders
- Department of TSE Molecular Biology, Veterinary Laboratories Agency, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - S Cawthraw
- Department of TSE Molecular Biology, Veterinary Laboratories Agency, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - S J Mountjoy
- Department of TSE Molecular Biology, Veterinary Laboratories Agency, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - J Hope
- Department of TSE Molecular Biology, Veterinary Laboratories Agency, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - O Windl
- Department of TSE Molecular Biology, Veterinary Laboratories Agency, New Haw, Addlestone, Surrey KT15 3NB, UK
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Baron T, Biacabe AG, Arsac JN, Benestad S, Groschup MH. Atypical transmissible spongiform encephalopathies (TSEs) in ruminants. Vaccine 2006; 25:5625-30. [PMID: 17126958 DOI: 10.1016/j.vaccine.2006.10.058] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2006] [Accepted: 10/30/2006] [Indexed: 11/22/2022]
Abstract
Transmissible spongiform encephalopathies (TSEs) are associated with the accumulation in infected tissues of a disease-associated form of a host-encoded protein, the prion protein (PrP). Contrary to the normal form of the protein, this form of PrP is partially resistant to protease digestion (PrP(res)). Detailed characterisation of PrP(res) has been intensively investigated in recent years to try and decipher the diversity of TSEs in human and animals. This considerably and unexpectedly enlarged our knowledge about such diseases in ruminants. Previously, such a diversity was essentially shown by the demonstration that scrapie from sheep and goats could have different biological behaviours following transmission of the disease in mice, unlike bovine spongiform encephalopathy from cattle (BSE) which showed a distinct and unique behaviour. The properties of the BSE agent were also demonstrated to be very stable, following transmission to a variety of different species. Molecular studies of PrP(res), followed by transmission studies to mice, gave the first evidence for the accidental transmission of the BSE agent to humans where it induced a variant form of the fatal Creutzfeldt-Jakob disease (CJD) and also to different animal species including a goat in France. This last case was found among a few unusual cases of TSEs in small ruminants that showed some molecular similarities with BSE and which are currently under investigation by transmission studies in mice. The application of the molecular methods to characterise PrP(res) has most recently led to the unexpected discovery of deviant BSE forms in a few affected cattle in Europe and in the United States, which raises the question of a possible different origin at least of some cases of BSE in cattle. Finally, considerable numbers of a new TSE form in small ruminants, referred to as "atypical scrapie" or "Nor98", have meanwhile been identified in most European countries by TSE rapid testing using an assay which recognizes also comparatively less PK resistant PrP(res).
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Affiliation(s)
- T Baron
- AFSSA-Lyon, Unité ATNC, Lyon, France.
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Opinion of the Scientific Panel on biological hazards (BIOHAZ) on the Breeding programme for TSE resistance in sheep. EFSA J 2006. [DOI: 10.2903/j.efsa.2006.382] [Citation(s) in RCA: 2] [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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Klingeborn M, Wik L, Simonsson M, Renström LHM, Ottinger T, Linné T. Characterization of proteinase K-resistant N- and C-terminally truncated PrP in Nor98 atypical scrapie. J Gen Virol 2006; 87:1751-1760. [PMID: 16690942 DOI: 10.1099/vir.0.81618-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
An increasing number of scrapie cases with atypical characteristics, designated Nor98, have recently been recognized. Here, the proteinase K (PK)-resistant prion protein (PrP) fragments from two Swedish cases of Nor98 atypical scrapie have been characterized. The prominent, fast-migrating band in the distinct Nor98 Western immunoblot electrophoretic profile was determined to be of 7 kDa in size and was accordingly designated Nor98-PrP7. The antigenic composition of Nor98-PrP7, as assayed by a panel of anti-PrP antibodies, revealed that this fragment comprised a mid-region of PrP from around aa 85 to 148. N- and C-terminally truncated fragments spanning the mid-region of PrP have only been observed in the genetic prion disorder Gerstmann–Sträussler–Scheinker disease. It is shown here that the long-term PK resistance of Nor98-PrP7 is reduced compared with that of PrPresin classical scrapie. Enzymic deglycosylation did not change the distinct electrophoretic profile of Nor98-PrP7. A previously unidentified, PK-resistant, C-terminal PrP fragment of around 24 kDa was detected and its PK resistance was investigated. After deglycosylation, this fragment migrated as a 14 kDa polypeptide and was designated PrP-CTF14. Antigenic determination and the size of 14 kDa suggested a fragment spanning approximately aa 120–233. The existence of two PK-resistant PrP fragments, Nor98-PrP7 and PrP-CTF14, that share an overlapping region suggests that at least two distinct PrP conformers with different PK-resistant cores are present in brain extracts from Nor98-affected sheep. The structural gene of PrP in three Nor98-affected sheep was analysed, but no mutations were found that could be correlated to the aberrant PK-resistant profile observed.
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Affiliation(s)
- Mikael Klingeborn
- Department of Molecular Biosciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Biomedical Centre, Box 588, S-751 23 Uppsala, Sweden
| | - Lotta Wik
- Department of Molecular Biosciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Biomedical Centre, Box 588, S-751 23 Uppsala, Sweden
| | - Magnus Simonsson
- Department of Molecular Biosciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Biomedical Centre, Box 588, S-751 23 Uppsala, Sweden
| | - Lena H M Renström
- Department of Virology, National Veterinary Institute, S-751 89 Uppsala, Sweden
| | - Therese Ottinger
- Department of Molecular Biosciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Biomedical Centre, Box 588, S-751 23 Uppsala, Sweden
| | - Tommy Linné
- Department of Molecular Biosciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Biomedical Centre, Box 588, S-751 23 Uppsala, Sweden
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Everest SJ, Thorne L, Barnicle DA, Edwards JC, Elliott H, Jackman R, Hope J. Atypical prion protein in sheep brain collected during the British scrapie-surveillance programme. J Gen Virol 2006; 87:471-477. [PMID: 16432036 DOI: 10.1099/vir.0.81539-0] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Scrapie of sheep and goats is the most common prion disease (or transmissible spongiform encephalopathy, TSE) of mammals and aggregates of abnormal, proteinase-resistant prion protein (PrPSc) are found in all naturally occurring prion diseases. During active surveillance of British sheep for TSEs, 29 201 sheep brain stem samples were collected from abattoirs and analysed for the presence of PrPSc. Of these samples, 54 were found to be positive by using an ELISA screening test, but 28 of these could not be confirmed initially by immunohistochemistry. These unconfirmed or atypical cases were generally found in PrP genotypes normally associated with relative resistance to clinical scrapie and further biochemical analysis revealed that they contained forms of PrPSc with a relatively protease-sensitive amyloid core, some resembling those of Nor98 scrapie. The presence of these atypical forms of protease-resistant PrP raises concerns that some TSE disorders of PrP metabolism previously may have escaped identification in the British sheep population.
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Affiliation(s)
- S J Everest
- Department of TSE Molecular Biology, Veterinary Laboratories Agency, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - L Thorne
- Department of TSE Molecular Biology, Veterinary Laboratories Agency, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - D A Barnicle
- Department of TSE Molecular Biology, Veterinary Laboratories Agency, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - J C Edwards
- Department of TSE Molecular Biology, Veterinary Laboratories Agency, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - H Elliott
- Institute for Animal Health, Pirbright Laboratory, Woking, Surrey, UK
| | - R Jackman
- Department of TSE Molecular Biology, Veterinary Laboratories Agency, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - J Hope
- Veterinary Laboratories Agency Lasswade, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK
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Opinion of the Scientific Panel on biological hazards (BIOHAZ) on classification of atypical Transmissible Spongiform Encephalopathy (TSE) cases in Small Ruminants. EFSA J 2005. [DOI: 10.2903/j.efsa.2005.276] [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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Scientific Report of the European Food Safety Authority on the Evaluation of Rapid post mortem TSE Tests intended for Small Ruminants. EFSA J 2005. [DOI: 10.2903/j.efsa.2005.49r] [Citation(s) in RCA: 2] [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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EFSA Scientific Report on the evaluation of rapid post mortem TSE tests intended for small ruminants. EFSA J 2005. [DOI: 10.2903/j.efsa.2005.31r] [Citation(s) in RCA: 8] [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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