Changes in allele and genotype frequencies of PrP gene in breeds of sheep in Slovakia between 2004 and 2015

Milan Margetín,Slavomír Reľovský,Zdenka Rajská,Jozef Bíreš,Marta Oravcová,Martin Mojžiš

doi:10.15414/afz.2016.19.03.119-122

Abstract

The objective of the study was to analyze the changes in allele and genotype frequencies of PrP gene in auction purebred rams of various breeds in Slovakia between 2004 and 2015. Male genotyping was done within the National Scrapie Eradication Programme by the certified laboratories. Positive changes in all breeds were found during the analyzed period. As a result of strict positive selection for ARR allele and strict negative selection for VRQ and ARQ alleles in most numerous Improved Valachian (IV) and Tsigai (TS) breeds, 94.7 % (IV) and 95.7 % (TS) of animals were included in the first and second risk (R1 and R2) groups in 2015. Frequencies of ARR allele were above 0.9 in specialized meat breeds. In Lacaune breed, frequencies of ARR, ARQ and VRQ alleles were 0.896, 0.117 and 0.003 in 2015. All purebred East Friesian males were included in R1 and R2 groups in 2015.

Highlights

Scrapie is a fatal neurodegenerative disease of the group of transmissible spongiform encephalopathies (TSE) in sheep and goats
The National Scrapie Eradication Programme is based on the Law No 39 of 2007 about veterinary care and the Regulation (EC) No 999 of 2001 of the European Parliament and of the Council laying down rules for the prevention, control and eradication of certain transmissible spongiform encephalopathies
Called classical scrapie is modulated by a combination of five possible alleles of PrP gene (ARR, AHQ, ARH, ARQ, VRQ), combination of which arises fifteen genotypes which are grouped in five risk groups: R1 to R5 (Dawson et al, 1998)

Summary

Introduction

Scrapie is a fatal neurodegenerative disease of the group of transmissible spongiform encephalopathies (TSE) in sheep and goats. The most effective way of eradication of classical srapie is genotyping of PrP gene and incorporation of this knowledge in selection (Dawson et al, 1998, Goldman, 2008). When eradication programmes in member states of EU were launched, it was supposed that animals with desirable PrP gene would have been resistant against any type of scrapie and that resistant animals would have not been the transmitters. Called classical scrapie is modulated by a combination of five possible alleles of PrP gene (ARR, AHQ, ARH, ARQ, VRQ), combination of which arises fifteen genotypes which are grouped in five risk groups: R1 to R5 (Dawson et al, 1998). Animals with ARQ allele are intermediately susceptible to scrapie (Hunter, 1997; Goldman, 2008)

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