Skip to main content
NCBI home page
Proceedings of the Royal Society B: Biological Sciences logoLink to Proceedings of the Royal Society B: Biological Sciences
. 2000 Oct 22;267(1457):2029–2035. doi: 10.1098/rspb.2000.1245

The signature of scrapie: differences in the PrP genotype profile of scrapie-affected and scrapie-free UK sheep flocks.

M Baylis 1, F Houston 1, W Goldmann 1, N Hunter 1, A R McLean 1
PMCID: PMC1690789  PMID: 11416905

Abstract

The amino-acid sequence of the PrP protein plays an important role in determining whether sheep are susceptible to scrapie. Although the genetics of scrapie susceptibility are now well understood, there have been few studies of the PrP gene at the population level, especially in commercially farmed sheep. Here we describe the PrP genetic profiles of the breeding stock of four UK sheep flocks, comprising nearly 650 animals in total. Two flocks had been scrapie affected for about eight years and two were scrapie free. Scrapie-resistant PrP genotypes predominated in all flocks but highly susceptible genotypes were present in each case. The distribution of PrP genotypes was similar in the scrapie-affected and scrapie-free flocks. The former, however, showed a slight but significant skew towards more susceptible genotypes despite their previous losses of susceptible sheep. Surprisingly, this skew was apparent in younger, but not older, sheep. We suggest that these patterns may occur if sheep flocks destined to become scrapie affected are predisposed by a genetic profile skewed towards susceptibility. The age structure of the scrapie-affected flocks suggests that the number of losses attributable directly or indirectly to scrapie considerably exceeds that recognized by the farmers, and also that significant losses may occur even in sheep of a moderately susceptible genotype. Similar patterns were not detected in the scrapie-free flocks, indicating that these losses are associated with scrapie infection as well as genotype.

Full Text

The Full Text of this article is available as a PDF (244.8 KB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Belt P. B., Muileman I. H., Schreuder B. E., Bos-de Ruijter J., Gielkens A. L., Smits M. A. Identification of five allelic variants of the sheep PrP gene and their association with natural scrapie. J Gen Virol. 1995 Mar;76(Pt 3):509–517. doi: 10.1099/0022-1317-76-3-509. [DOI] [PubMed] [Google Scholar]
  2. Caughey B., Chesebro B. Prion protein and the transmissible spongiform encephalopathies. Trends Cell Biol. 1997 Feb;7(2):56–62. doi: 10.1016/S0962-8924(96)10054-4. [DOI] [PubMed] [Google Scholar]
  3. Clark A. M., Dawson M., Scott A. C. Scrapie associated fibrils in found dead sheep. Vet Rec. 1994 Jun 18;134(25):650–651. doi: 10.1136/vr.134.25.650. [DOI] [PubMed] [Google Scholar]
  4. Clark A. M., Moar J. A. Scrapie: a clinical assessment. Vet Rec. 1992 Apr 25;130(17):377–378. doi: 10.1136/vr.130.17.377. [DOI] [PubMed] [Google Scholar]
  5. Dawson M., Hoinville L. J., Hosie B. D., Hunter N. Guidance on the use of PrP genotyping as an aid to the control of clinical scrapie. Scrapie Information Group. Vet Rec. 1998 Jun 6;142(23):623–625. [PubMed] [Google Scholar]
  6. Detwiler L. A. Scrapie. Rev Sci Tech. 1992 Jun;11(2):491–537. doi: 10.20506/rst.11.2.607. [DOI] [PubMed] [Google Scholar]
  7. Dickinson A. G. Scrapie in sheep and goats. Front Biol. 1976;44:209–241. [PubMed] [Google Scholar]
  8. Foster J. D., Wilson M., Hunter N. Immunolocalisation of the prion protein (PrP) in the brains of sheep with scrapie. Vet Rec. 1996 Nov 23;139(21):512–515. doi: 10.1136/vr.139.21.512. [DOI] [PubMed] [Google Scholar]
  9. Goldmann W., Hunter N., Smith G., Foster J., Hope J. PrP genotype and agent effects in scrapie: change in allelic interaction with different isolates of agent in sheep, a natural host of scrapie. J Gen Virol. 1994 May;75(Pt 5):989–995. doi: 10.1099/0022-1317-75-5-989. [DOI] [PubMed] [Google Scholar]
  10. Hoinville L., McLean A. R., Hoek A., Gravenor M. B., Wilesmith J. Scrapie occurrence in Great Britain. Vet Rec. 1999 Oct 2;145(14):405–406. doi: 10.1136/vr.145.14.405. [DOI] [PubMed] [Google Scholar]
  11. Hunter N., Goldmann W., Benson G., Foster J. D., Hope J. Swaledale sheep affected by natural scrapie differ significantly in PrP genotype frequencies from healthy sheep and those selected for reduced incidence of scrapie. J Gen Virol. 1993 Jun;74(Pt 6):1025–1031. doi: 10.1099/0022-1317-74-6-1025. [DOI] [PubMed] [Google Scholar]
  12. Hunter N., Goldmann W., Foster J. D., Cairns D., Smith G. Natural scrapie and PrP genotype: case-control studies in British sheep. Vet Rec. 1997 Aug 9;141(6):137–140. doi: 10.1136/vr.141.6.137. [DOI] [PubMed] [Google Scholar]
  13. Hunter N. PrP genetics in sheep and the applications for scrapie and BSE. Trends Microbiol. 1997 Aug;5(8):331–334. doi: 10.1016/s0966-842x(97)01081-0. [DOI] [PubMed] [Google Scholar]
  14. Ikeda T., Horiuchi M., Ishiguro N., Muramatsu Y., Kai-Uwe G. D., Shinagawa M. Amino acid polymorphisms of PrP with reference to onset of scrapie in Suffolk and Corriedale sheep in Japan. J Gen Virol. 1995 Oct;76(Pt 10):2577–2581. doi: 10.1099/0022-1317-76-10-2577. [DOI] [PubMed] [Google Scholar]
  15. Mclean A. R., Hoek A., Hoinville L. J., Gravenor M. B. Scrapie transmission in Britain: a recipe for a mathematical model. Proc Biol Sci. 1999 Dec 22;266(1437):2531–2538. doi: 10.1098/rspb.1999.0956. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. van Keulen L. J., Schreuder B. E., Meloen R. H., Poelen-van den Berg M., Mooij-Harkes G., Vromans M. E., Langeveld J. P. Immunohistochemical detection and localization of prion protein in brain tissue of sheep with natural scrapie. Vet Pathol. 1995 May;32(3):299–308. doi: 10.1177/030098589503200312. [DOI] [PubMed] [Google Scholar]

Articles from Proceedings of the Royal Society B: Biological Sciences are provided here courtesy of The Royal Society

RESOURCES