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Review: A review on classical and atypical scrapie in caprine: Prion protein gene polymorphisms and their role in the disease

Published online by Cambridge University Press:  25 April 2016

L. Curcio ,
C. Sebastiani ,
P. Di Lorenzo ,
E. Lasagna  and
M. Biagetti
L. Curcio*
Affiliation:
Area Ricerca e Sviluppo, Istituto Zooprofilattico Sperimentale dell’Umbria e delle Marche, Via G. Salvemini 1, 06126 Perugia, Italy Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, Borgo XX Giugno 74, 06121, Perugia, Italy
C. Sebastiani
Affiliation:
Area Ricerca e Sviluppo, Istituto Zooprofilattico Sperimentale dell’Umbria e delle Marche, Via G. Salvemini 1, 06126 Perugia, Italy
P. Di Lorenzo
Affiliation:
Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, Borgo XX Giugno 74, 06121, Perugia, Italy
E. Lasagna
Affiliation:
Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, Borgo XX Giugno 74, 06121, Perugia, Italy
M. Biagetti
Affiliation:
Area Ricerca e Sviluppo, Istituto Zooprofilattico Sperimentale dell’Umbria e delle Marche, Via G. Salvemini 1, 06126 Perugia, Italy
*
†E-mail: [email protected]
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Abstract

Scrapie is a naturally occurring transmissible spongiform encephalopathy in sheep and goat. It has been known for ~250 years and is characterised by the accumulation of an abnormal isoform of a host-encoded prion protein that leads to progressive neurodegeneration and death. Scrapie is recognised in two forms, classical and atypical scrapie. The susceptibility to both types of scrapie is influenced by polymorphisms of the prion protein gene (PRNP). Sheep susceptibility or resistance to classical scrapie is strongly regulated by the polymorphisms at codons 136, 154 and 171 of the PRNP. The genetic role in atypical scrapie in sheep has been defined by polymorphisms at codons 141, 154 and 171, which are associated with different degrees of risk in the occurrence of the ovine disease. Progress has been achieved in the prevention of scrapie in sheep due to efficient genetic breeding programmes based on eradication and control of the disease. In Europe, the success of these programmes has been verified by applying eradication and genetic selection plans. In general terms, the ovine selection plans aim to eliminate and reduce the susceptible allele and to enrich the resistant allele ARR. During outbreaks all susceptible animals are slaughtered, only ARR/ARR resistant rams and sheep and semi-resistant females are preserved. In the occurrence of scrapie positive goats a complete cull of the flock (stamping out) is performed with great economic loss and severe risk of extinction for the endangered breeds. The ability to select scrapie-resistant animals allows to define new breeding strategies aimed to boost genetic progress while reducing costs during scrapie outbreaks. Allelic variants of PRNP can be protective for caprine scrapie, and the knowledge of their distribution in goats has become very important. Over the past few years, the integration of genetic information on goat populations could be used to make selection decisions, commonly referred to as genetic selection. The objective of this review was to summarise the main findings of polymorphisms of the caprine prion protein (PrP) gene and to discuss the possible application of goat breeding schemes integrating genetic selection, with their relative advantages and limitations.

Keywords

transmissible spongiform encephalopathygoatgenetic selection
Type
Review Article
Information
animal , Volume 10 , Issue 10 , October 2016 , pp. 1585 - 1593
Copyright
© The Animal Consortium 2016 

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Footnotes

a

These authors contributed equally to this work.

References

Acín, C, Martín-Burriel, I, Monleón, E, Lyahyai, J, Pitarch, JL, Serrano, C, Monzòn, M, Zaragoza, P and Badiola, JJ 2013. Prion protein gene variability in Spanish goats. Inference through susceptibility to classical scrapie strains and pathogenic distribution of peripheral PrPsc. PLoS One 8, 4.CrossRefGoogle ScholarPubMed
Acutis, PL, Martucci, F, D’Angelo, A, Peletto, S, Colussi, S, Maurella, C, Porcario, C, Iulini, B, Mazza, M, Dell’Atti, L, Zuccon, F, Corona, C, Martinelli, N, Casalone, C, Caramelli, M and Lombardi, G 2012. Resistance to classical scrapie in experimentally challenged goats carrying mutation K222 of the prion protein gene. Veterinary Research 43, 8.CrossRefGoogle ScholarPubMed
Acutis, PL, Santagata, G, Colussi, S, Maniaci, MG, Sacchi, P, Laurenza, C, Riina, MV, Peletto, S, Zuccon, F, Caramelli, M and Rasero, R 2007. Polymorphism of goat PrP gene in Northern and Southern Italian breeds. Italian Journal of Animal Science 6, 39.Google Scholar
Agrimi, U, Conte, M, Morelli, L, Di Bari, MA, Di Guardo, G, Ligios, C, Antonucci, G, Aufiero, G, Pozzato, N, Mutinelli, F, Nonno, R and Vaccari, G 2003. Animal transmissible spongiform encephalopathies and genetics. Veterinary Research Communications 27, 31–38.CrossRefGoogle ScholarPubMed
Aguilar-Calvo, P, Espinosa, JC, Pintado, B, Gutiérrez-Adán, A, Alamillo, E, Miranda, A, Prieto, I, Bossers, A, Andreoletti, O and Torres, JM 2014. Role of the goat K222-PrPC polymorphic variant in prion infection resistance. Journal of Virology 88, 2670–2676.CrossRefGoogle ScholarPubMed
Aguilar-Calvo, P, Fast, C, Tauscher, K, Espinosa, JC, Groschup, MH, Nadeem, M, Goldmann, W, Langeveld, J, Bossers, A, Andreoletti, O and Torres, JM 2015. Effect of Q211 and K222 PRNP polymorphic variants in the susceptibility of goats to oral infection with Goat-BSE. Journal of Infectious Diseases 212, 664–672.CrossRefGoogle Scholar
Aguzzi, A, Heikenwalder, M and Polymenidou, M 2007. Insights into prion strains and neurotoxicity. Nature Reviews Molecular Cell Biology 8, 552–561.CrossRefGoogle ScholarPubMed
Andréoletti, O, Orge, L, Benestad, SL, Beringue, V, Litaise, C, Simon, S, Le Dur, A, Laude, H, Simmons, H, Lugan, S, Corbière, F, Costes, P, Morel, N, Schelcher, F and Lacroux, C 2011. Atypical/Nor98 scrapie infectivity in sheep peripheral tissues. PLoS Pathogens 7, e1001285–e1001285.CrossRefGoogle ScholarPubMed
Babar, ME, Farid, A, Benkel, BF, Ahmad, J, Nadeem, A and Imran, M 2009. Frequencies of PrP genotypes and their implication for breeding against scrapie susceptibility in nine Pakistani sheep breeds. Molecular Biology Reports 36, 561–565.CrossRefGoogle ScholarPubMed
Baylis, M and Goldmann, W 2004. The genetics of scrapie in sheep and goats. Current Molecular Medicine 4, 385–396.CrossRefGoogle ScholarPubMed
Benestad, SL, Arsac, JN, Goldmann, W and Nöremark, M 2008. Atypical/Nor98 scrapie: properties of the agent, genetics, and epidemiology. Veterinary Research 39, 1–14.CrossRefGoogle ScholarPubMed
Benestad, SL, Sarradin, P, Thu, B, Schönheit, J, Tranulis, MA and Bratberg, B 2003. Cases of scrapie with unusual features in Norway and designation of a new type, Nor98. The Veterinary Record 153, 202–208.CrossRefGoogle ScholarPubMed
Capucchio, MT, Guarda, F, Isaia, MC, Caracappa, S and Di Marco, V 1998. Natural occurrence of scrapie in goats in Italy. Veterinary Record 143, 452–453.CrossRefGoogle ScholarPubMed
Cassard, H, Torres, JM, Lacroux, C, Douet, JY, Benestad, SL, Lantier, F, Lugan, F, Lantier, I, Costes, P, Aron, N, Reine, F, Herzog, L, Espinosa, JC, Beringue, V and Andréoletti, O 2014. Evidence for zoonotic potential of ovine scrapie prions. Nature Communications 5, 5821–5829.CrossRefGoogle ScholarPubMed
Collinge, J, Whitfield, J, McKintosh, E, Beck, J, Mead, S, Thomas, DJ and Alpers, MP 2006. Kuru in the 21st century an acquired human prion disease with very long incubation periods. The Lancet 367, 2068–2074.CrossRefGoogle ScholarPubMed
Colussi, S, Vaccari, G, Maurella, C, Bona, C, Lorenzetti, R, Troiano, P, Casalinuovo, F, Di Sarno, A, Maniaci, MG, Zuccon, F, Nonno, R, Casalone, C, Mazza, M, Ru, G, Caramelli, M, Agrimi, U and Acutis, PL 2008. Histidine at codon 154 of the prion protein gene is a risk factor for Nor98 scrapie in goats. Journal of General Virology 89, 3173–3176.CrossRefGoogle ScholarPubMed
Colussi, S, Vaccari, G, Maurella, C, Bona, C, Lorenzetti, R, Troiano, P, Casalinuovo, F, Di Sarno, A, Maniaci, MG, Zuccon, F, Nonno, R, Casalone, C, Mazza, M, Ru, G, Caramelli, M, Agrimi, U and Acutis, PL 2009. L’allele AHQ quale fattore di rischio per la scrapie atipica Nor98 nella capra. Large Animal Review 15, 61–64.Google Scholar
Colussi, S, Vaccari, G, Rasero, R, Ponti, AM, Ru, G, Sacchi, P, Caramelli, M, Agrimi, U and Acutis, PL 2010. Prospects for applying breeding for resistance to control scrapie in goats: The current situation in Italy. Small Ruminant Research 88, 97–101.CrossRefGoogle Scholar
Comoy, EE, Mikol, J, Luccantoni-Freire, S, Correia, E, Lescoutra-Etchegaray, N, Durand, V, Dehen, C, Andréoletti, O, Casalone, C, Richt, JA, Greenlee, JJ, Baron, T, Benestad, SL, Brown, P and Deslys, JP 2015. Transmission of scrapie prions to primate after an extended silent incubation period. Scientific Reports 5, 11573–11583.CrossRefGoogle ScholarPubMed
Commission Decision 2002/1003/EC 2002. Commission Decision of 18 December 2002 laying down minimum requirements for a survey of prion protein genotypes of sheep breeds. Official Journal of the European Union L349, 106–107. Retrieved on 27 September 2015 from http://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32002D1003&from=EN.Google Scholar
Commission Decision 2003/100/EC 2003. Commission Decision of laying down minimum requirements for the establishment of breeding programmes for resistance to transmissible spongiform encephalopathies in sheep. Official Journal of the European Union L41, 41–43. Retrieved on 27 September 2015 from http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=uriserv:OJ.L_.2003.041.01.0041.01.ENG.Google Scholar
Corbière, F, Perrin-Chauvineau, C, Lacroux, C, Costes, P, Thomas, M, Bremaud, I, Martin, S, Lugan, S, Chartier, C, Schelcher, F, Barillet, F and Andréoletti, O 2013. PrP-associated resistance to scrapie in five highly infected goat herds. Journal of General Virology 94, 241–245.CrossRefGoogle ScholarPubMed
Coseddu, GM, Agrimi, U, Pinto, J and Schudel, AA 2007. Advances in scrapie research. Scientific and Technical Review of the Office International des Epizooties 26, 657–668.Google Scholar
Dassanayake, RP, White, SN, Madsen-Bouterse, SA, Schneider, DA and O’Rourke, KI 2015. Role of the PRNP S127 allele in experimental infection of goats with classical caprine scrapie. Animal Genetics 46, 341–341.CrossRefGoogle ScholarPubMed
Dawson, M, Moore, RC and Bishop, SC 2008. Progress and limits of PrP gene selection policy. Veterinary Research 39, 1–12.CrossRefGoogle ScholarPubMed
Dawson, M and Vilas, VDR 2008. Control of classical scrapie in Great Britain. In Practice 30, 330–333.CrossRefGoogle Scholar
Detwiler, LA 1992. Scrapie. Revue scientifique et technique (International Office of Epizootics) 11, 491–537.Google ScholarPubMed
Dobly, A, van der Heyden, S and Roels, S 2013. Trends in genotype frequency resulting from breeding for resistance to classical scrapie in Belgium (2006–2011). Journal of Veterinary Science 14, 45–51.CrossRefGoogle Scholar
Eiden, M, Soto, EO, Mettenleiter, TC and Groschup, MH 2011. Effects of polymorphisms in ovine and caprine prion protein alleles on cell-free conversion. Veterinary Research 42, 30.CrossRefGoogle ScholarPubMed
Eloit, M, Adjou, K, Coulpier, M, Fontaine, JJ, Hamel, R, Lilin, T, Messiaen, S, Andréoletti, O, Baron, T, Bencsik, A, Biacabe, AG, Beringue, V, Laude, H, Le Dur, A, Vilotte, JL, Comoy, E, Deslys, P, Grassi, J, Simon, S, Lantier, F and Sarradin, P 2005. BSE agent signatures in a goat. The Veterinary Record 156, 523–524.CrossRefGoogle Scholar
Elsen, JM, Moreno, CR, Bodin, L, François, D, Bouix, J, Barillet, F, Lantier, F, Lantier, I, Schibler, L, Roig, A, Brunel, JC and Vitezica, ZG 2006. Selection for scrapie resistance in France: is there evidence of negative effects on production and health traits? In Proceedings of the 8th World Congress on Genetics Applied to Livestock Production, Instituto Prociência, 13 to 18 August, 2006. Belo Horizonte, Minas Gerais, Brazil (pp. 15–15).Google Scholar
Eurosurveillance 2005. BSE-related health risks from goat meat: scientific opinion from the European Food Safety Authority. Retrieved on 27 September 2015 from http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=2736.Google Scholar
European Commission 2010. Directorate-General for Health & consumers. The TSE Roadmap 2. Report: COM 2010. Retrieved on 27 September 2015 from http://ec.europa.eu/food/food/biosafety/tse_bse/docs/roadmap_2_en.pdf.Google Scholar
European Commission 2012. Report on the monitoring of ruminants for the presence of in the EU in 2012. Transmissible Spongiform. Encephalopathies (TSEs). Retrieved on 27 September 2015 from http://ec.europa.eu/food/food/biosafety/tse_bse/docs/annual_report_tse2012_en.pdf.Google Scholar
European Food Safety Authority (EFSA) 2009. Scientific Opinion on genetic TSE resistance in goats in all European Union Member States. European Food Safety Authority Journal 7, 1371–1413.Google Scholar
European Food Safety Authority (EFSA) 2014. Scientific Opinion on the scrapie situation in the EU after 10 years of monitoring and control in sheep and goats. European Food Safety Authority Journal 12, 3781–3936.Google Scholar
Fast, C and Groschup, MH 2013. Classical and atypical scrapie in sheep and goats: in prions and diseases. In Prions and diseases. Animals, humans and the environment (ed. W-Q, Zou and P, Gambetti), pp. 15–44. Springer Science & Business Media, New York, NY, USA.Google Scholar
Gavier-Widén, D, Stack, MJ, Baron, T, Balachandran, A and Simmons, M 2005. Diagnosis of transmissible spongiform encephalopathies in animals: a review. Journal of Veterinary Diagnostic Investigation 17, 509–527.CrossRefGoogle ScholarPubMed
Glatzel, M and Aguzzi, A 2001. The shifting biology of prions. Brain Research Review 36, 241–248.CrossRefGoogle ScholarPubMed
Goldmann, W 2008. PrP Genetics in ruminant transmissible spongiform encephalopathies. Veterinary Research 39, 1–14.CrossRefGoogle ScholarPubMed
Goldmann, W, Marier, E, Stewart, P, Konold, T, Street, S, Langeveld, J, Windl, O and Ortiz-Pelaez, A 2016. Prion protein genotype survey confirms low frequency of scrapie-resistant K222 allele in British goat herds. Veterinary Record 178, 168–174.CrossRefGoogle ScholarPubMed
Goldmann, W, Ryan, K, Stewart, P, Parnham, D, Xicohtencatl, R, Fernandez, N and Foster, J 2011. Caprine prion gene polymorphisms are associated with decreased incidence of classical scrapie in goat herds in the United Kingdom. Veterinary Research 42, 110–118.CrossRefGoogle ScholarPubMed
González, L, Jeffrey, M, Dagleish, MP, Goldmann, W, Sisó, S, Eaton, SL, Martin, S, Finlayson, J, Stewart, P, Steele, P, Pang, Y, Hamilton, S, Reid, HW and Chianini, F 2012. Susceptibility to scrapie and disease phenotype in sheep: cross-PRNP genotype experimental transmissions with natural sources. Veterinary Research 43, 55–68.CrossRefGoogle ScholarPubMed
Götte, DR, Benestad, SL, Laude, H, Zurbriggen, A, Oevermann, A and Seuberlich, T 2011. Atypical scrapie isolates involve a uniform prion species with a complex molecular signature. PLos One 6, e27510, doi:10.1371/journal.pone.0027510.CrossRefGoogle ScholarPubMed
Hagenaars, TJ, Melchior, MB, Bossers, A, Davidse, A, Engel, B and van Zijderveld, FG 2010. Scrapie prevalence in sheep of susceptible genotype is declining in a population subject to breeding for resistance. BMC Veterinary Research 6, 25.CrossRefGoogle Scholar
Hunter, N 1997. PrP genetics in sheep and the implications for scrapie and BSE. Trends in Microbiology 5, 331–334.CrossRefGoogle Scholar
Hussain, A, Babar, ME, Imran, M, Haq, IU and Javed, MM 2011. Detection of four novel polymorphisms in PrP gene of Pakistani sheep (Damani and Hashtnagri) and goats (Kamori and Local Hairy) breeds. Virology Journal 8, 1–5.CrossRefGoogle ScholarPubMed
Jeffrey, M, González, L, Espenes, A, Press, C, Martin, S, Chaplin, M, Davis, L, Landsverk, T, MacAldowie, C, Eaton, S and McGovern, G 2006. Transportation of prion protein across the intestinal mucosa of scrapie-susceptible and scrapie-resistant sheep. The Journal of Pathology 209, 4–14.CrossRefGoogle ScholarPubMed
Kanata, E, Humphreys-Panagiotidis, C, Giadinis, ND, Papaioannou, N, Arsenakis, M and Sklaviadis, T 2014. Perspectives of a scrapie resistance breeding scheme targeting Q211, S146 and K222 caprine PRNP alleles in Greek goats. Veterinary Research 45, 43–49.CrossRefGoogle ScholarPubMed
Kipanyula, MJ, Chuma, IS, Brundtland, E, Bårdsen, K, Msalya, G, Kifaro, GC and Ulvund, MJ 2014. Prion protein (PrP) gene polymorphisms in Small East African and Norwegian white goats. Small Ruminant Research 121, 200–206.CrossRefGoogle Scholar
Kittelberger, R, Chaplin, MJ, Simmons, MM, Ramirez-Villaescusa, A, McIntyre, L, MacDiarmid, SC, Hannah, MJ, Jenner, J, Bueno, R, Bayliss, D, Black, H, Pigott, CJ and O’Keefe, JS 2010. Atypical scrapie/Nor98 in a sheep from New Zealand. Journal of Veterinary Diagnostic Investigation 22, 863–875.CrossRefGoogle Scholar
Lacroux, C, Perrin-Chauvineau, C, Corbière, F, Aron, N, Aguilar-Calvo, P, Torres, JM, Costes, P, Brémaud, I, Lugan, S, Schelcher, F, Barillet, F and Andréoletti, O 2014. Genetic resistance to scrapie infection in experimentally challenged goats. Journal of Virology 88, 2406–2413.CrossRefGoogle ScholarPubMed
Lühken, G, Buschmann, A, Groschup, MH and Erhardt, G 2004. Prion protein allele A136 H 154 Q 171 is associated with high susceptibility to scrapie in purebred and crossbred German Merinoland sheep. Archives of Virology 149, 1571–1580.CrossRefGoogle ScholarPubMed
Lühken, G, Buschmann, A, Brandt, H, Eiden, M, Groschup, MH and Erhardt, G 2007. Epidemiological and genetical differences between classical and atypical scrapie cases. Veterinary Research 38, 65–80.CrossRefGoogle ScholarPubMed
Meydan, H, Ozkan, MM, Yildiz, MA and Goldmann, W 2013. Novel polymorphisms in ovine prion protein gene. Animal Genetics 44, 588–591.CrossRefGoogle ScholarPubMed
Migliore, S, Agnello, S, Chiappini, B, Vaccari, G, Mignacca, SA, Di Marco Lo Presti, V, Di Domenico, F and Vitale, M 2015. Biodiversity and selection for scrapie resistance in goats: Genetic polymorphism in ‘Girgentana’ breed in Sicily, Italy. Small Ruminant Research 125, 137–141.CrossRefGoogle Scholar
Mitchell, GB, O’Rourke, KI, Harrington, NP, Soutyrine, A, Simmons, MM, Dudas, S, Zhuang, D, Laude, H and Balachandran, A 2010. Identification of atypical scrapie in Canadian sheep. Journal of Veterinary Diagnostic Investigation 22, 408–411.CrossRefGoogle ScholarPubMed
Moum, T, Olsaker, I, Hopp, P, Moldal, T, Valheim, M, Moum, T and Benestad, SL 2005. Polymorphisms at codons 141 and 154 in the ovine prion protein gene are associated with scrapie Nor98 cases. Journal of General Virology 86, 231–235.CrossRefGoogle ScholarPubMed
Nodelijk, G, Van Roermund, HJ, Van Keulen, LJ, Engel, B, Vellema, P and Hagenaars, TJ 2011. Breeding with resistant rams leads to rapid control of classical scrapie in affected sheep flocks. Veterinary Research 42, 1–11.CrossRefGoogle ScholarPubMed
OIE Terrestrial Manual 2012. Scrapie. pp. 1045–1054. Retrieved on 27 September 2015 from http://www.oie.int/fileadmin/Home/fr/Health_standards/tahm/2.07.13_SCRAPIE.pdf.Google Scholar
O’Rourke, KI, Zhuang, D, Truscott, TC, Yan, H and Schneider, DA 2011. Sparse PrPSc accumulation in the placentas of goats with naturally acquired scrapie. BMC Veterinary Research 7, 7–16.CrossRefGoogle ScholarPubMed
Ortiz-Pelaez, A, Thompson, CE and Dawson, M 2014. The impact of the National Scrapie Plan on the PRNP genotype distribution of the British national flock, 2002-2012. Veterinary Record 174, 530.CrossRefGoogle ScholarPubMed
Ortiz-Pelaez, A, Georgiadou, S, Simmons, MM, Windl, O, Dawson, M, Arnold, ME, Neocleous, P and Papasavva-Stylianou, P 2015. Allelic variants at codon 146 in the PRNP gene show significant differences in the risk for natural scrapie in Cypriot goats. Epidemiology and Infection 143, 1304–1310.CrossRefGoogle ScholarPubMed
Pongolini, S, Bergamini, F, Iori, A, Migliore, S, Corradi, A and Bassi, S 2009. Prion protein genotypes of Italian sheep breeds with Lysine-171 and phenylalanine-141 detection. Veterinary Microbiology 137, 18–23.CrossRefGoogle ScholarPubMed
Pritchard, TC, Cahalan, CM and Dewi, IAp 2008. Association between PrP genotypes and performance traits in a Welsh Mountain flock. Animal 2, 1421–1426.CrossRefGoogle Scholar
Prusiner, SB 1991. Molecular biology of prion diseases. Science 252, 1515–1522.CrossRefGoogle ScholarPubMed
Prusiner, SB 2004. Prion biology and diseases, 2nd edition. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York, NY, USA.Google Scholar
Prusiner, SB 2013. Biology and genetics of prions causing neurodegeneration. Annual Review of Genetics 47, 601–623.CrossRefGoogle ScholarPubMed
Radostits, OM, Gay, C and Blood, C 2007. A textbook of the disease of cattle, sheep, pigs, goats and horses. Veterinary Medicine, 1440–1446.Google Scholar
Regulation (EC) No 999/2001 2001. Regulation (EC) No 999/2001 of the European Parliament and of the Council of 22 May 2001 laying down rules for the prevention, control and eradication of certain transmissible spongiform encephalopathies. Official Journal of the European Union L147, 1–40. Retrieved on 27 September 2015 from http://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX:32001R0999.Google Scholar
Regulation (EC) No 727/2007 2007. Regulation (EC) No 727/2007 of 26 June 2007 amending Annexes I, III, VII and X to Regulation (EC) No 999/2001 of the European Parliament and of the Council laying down rules for the prevention, control and eradication of certain transmissible spongiform encephalopathies. Official Journal of the European Union L165, 8–20. Retrieved on 27 September 2015 from http://eur-lex.europa.eu/legal-content/EN/TXT/?qid=1429005855785&uri=CELEX:02007R0727-20070717.Google Scholar
Schneider, DA, Madsen-Bouterse, SA, Zhuang, D, Truscott, TC, Dassanayake, RP and O’Rourke, KI 2015. The placenta shed from goats with classical scrapie is infectious to goat kids and lambs. Journal of General Virology 96, 2464–2469.CrossRefGoogle ScholarPubMed
Simmons, MM, Konold, T, Simmons, HA, Spencer, YI, Lockey, R, Spiropoulos, J, Everitt, S and Clifford, D 2007. Experimental transmission of atypical scrapie to sheep. BMC Veterinary Research 3, 20.CrossRefGoogle ScholarPubMed
Simmons, MM, Konold, T, Thurston, L, Bellworthy, SJ, Chaplin, MJ and Moore, SJ 2010. The natural atypical scrapie phenotype is preserved on experimental transmission and sub-passage in PRNP homologous sheep. BMC Veterinary Research 6, 14.CrossRefGoogle ScholarPubMed
Simmons, MM, Moore, SJ, Konold, T, Thurston, L, Terry, LA, Thorne, L, Lockey, R, Vickery, C, Hawkins, SAC, Chaplin, MJ and Spiropoulos, J 2011. Experimental oral transmission of atypical scrapie to sheep. Emerging Infectious Diseases 17, 848–854.CrossRefGoogle ScholarPubMed
Ulvund, MJ, Bårdsen, K, Brundtland, E, Meling, S, Ersdal, C, Espenes, A and Press, CM 2007. A new experimental model for studying scrapie and prion disease in sheep. In Proceedings of the Prion 2007 Conference, 26 to 28 September 2007. Edinburgh, Scotland, UK.Google Scholar
United States Department of Agriculture (USDA) 2015. National Scrapie Eradication Program. Retrieved on 27 September 2015 from http://www.aphis.usda.gov/wps/portal/aphis/ourfocus/animalhealth/sa_animal_disease_information/.Google Scholar
Vaccari, G, Panagiotidis, CH, Acin, C, Peletto, S, Barillet, F, Acutis, P, Bossers, A, Langeveld, J, van Keulen, L, Sklaviadis, T, Badiola, JJ, Andréoletti, O, Groschup, MH, Agrimi, U, Foster, J and Goldmann, W 2009. State-of-the-art review of goat TSE in the European Union, with special emphasis on PRNP genetics and epidemiology. Veterinary Research 40, 1–18.CrossRefGoogle ScholarPubMed
Vitezica, ZG, de Heredia, IB and Ugarte, E 2013. Short communication: Analysis of association between the prion protein (PRNP) locus and milk traits in Latxa dairy sheep. Journal of dairy science 96, 6079–6083.CrossRefGoogle ScholarPubMed
Vitezica, ZG, Moreno, CR, Bodin, L, François, D, Barillet, F, Brunel, JC and Elsen, JM 2006. No associations between PrP genotypes and reproduction traits in INRA 401 sheep. Journal of animal science 84, 1317–1322.CrossRefGoogle ScholarPubMed
Vitezica, ZG, Moreno, CR, Bouix, J, Barillet, F, Perret, G and Elsen, JM 2005. A study on associations between PrP genotypes and meat traits in French sheep breeds. Animal Science 81, 325–330.CrossRefGoogle Scholar
Wadsworth, JDF, Joiner, S, Linehan, JM, Balkema-Buschmann, A, Spiropoulos, J, Simmons, MM, Griffiths, PC, Groschup, MH, Hope, J, Brandner, S, Asante, EA and Collinge, J 2013. Atypical scrapie prions from sheep and lack of disease in transgenic mice overexpressing human prion protein. Emerging Infectious Diseases 19, 1731–1739.CrossRefGoogle ScholarPubMed
White, S, Herrmann-Hoesing, L, O’Rourke, K, Waldron, D, Rowe, J and Alverson, J 2008. Prion gene (PRNP) haplotype variation in United States goat breeds. Genetics Selection Evolution 40, 553–561.Google ScholarPubMed
White, S, Reynolds, JO, Waldron, DF, Schneider, DA and O’Rourke, KI 2012. Extended scrapie incubation time in goats singly heterozygous for PRNP S146 or K222. Gene 501, 49–51.CrossRefGoogle ScholarPubMed
Zhou, R, Li, X, Xi, J, Li, L, Zhang, Z and Zhao, Z 2013. Genetic variability of PRNP in Chinese indigenous goats. Biochemical Genetics 51, 211–222.CrossRefGoogle ScholarPubMed