Free access
Review
Issue
Vet. Res.
Volume 39, Number 4, July-August 2008
Prion diseases in animals
Number of page(s) 18
DOI http://dx.doi.org/10.1051/vetres:2008004
Published online 15 February 2008
How to cite this article Vet. Res. (2008) 39:28
How to cite this article: Vet. Res. (2008) 39:28
DOI: 10.1051/vetres:2008004

Review

The evidence of associations between prion protein genotype and production, reproduction, and health traits in sheep

Torres Sweeney1 and John P. Hanrahan2

1  School of Agriculture, Food Science and Veterinary Medicine, Conway Institute of Biomolecular and Biomedical Sciences, University College Dublin, Belfield, Dublin 4, Ireland
2  Teagasc, Animal Production Research Centre, Athenry, Co, Galway, Ireland

Received 28 September 2007; accepted 15 January 2007; published online 15 February 2008

Abstract - The EU Commission issued a regulation in 2003, which requires all member states to implement a breeding programme for resistance to transmissible spongiform encephalopathies in sheep by selecting for specific alleles of the prion protein (PrP) gene. A key concern with regard to this regulation was that the intensive selection programmes, designed to increase resistance to scrapie, may have a negative impact on a range of other economically important production, reproduction, and disease traits in sheep. Such problems could arise for a number of reasons. Firstly, a number of breeds have a low frequency of the resistant PrP allele. Secondly, there may be a negative association between the resistant allele and animal performance. Thirdly, selection for scrapie resistance may reduce the rate of improvement towards current breeding goals. The evidence concerning the relationship between PrP genotype and reproduction, production, and disease traits is the subject of this review. We conclude that there is no evidence for a negative association between PrP genotype and reproduction traits (e.g. litter size), lamb performance traits (e.g. growth rate, conformation, carcass composition) or milk production. There is, however, a distinct paucity of information on the relationship between the PrP gene and disease traits. In this context it is noted that there are a number of genes located on chromosome 13, in close proximity to the PrP gene, that are involved in intracellular cell signalling, apoptosis, phagocytosis, and immune function. Thus further direct studies of key disease traits associated with sheep production systems are warranted.


Key words: PrP genotype / growth / carcass / prolificacy / disease

Corresponding author: torres.sweeney@ucd.ie

© INRA, EDP Sciences 2008