Prion protein gene polymorphism and genetic risk evaluation for scrapie in all Turkish native sheep breeds

Abstract

The aim of this study was to identify the prion protein (PrP) gene polymorphism in a total of 1,110 healthy sheep from 18 Turkish native sheep breeds. There were nine alleles and 22 genotypes observed based on codons 136, 154, and 171 of the PrP gene. The ARQ allele was predominant for all breeds. The most resistant allele to scrapie, ARR, was present in all breeds. The VRQ allele, associated with the highest susceptibility to scrapie, was detected at low frequencies in İvesi (0.06), Kıvırcık (0.021), Sakız (0.010), Karayaka (0.011), Çine Çaparı (0.012), and Güneykaraman (0.017). In general, the ARQ/ARQ genotype was predominant in all breeds. The most resistant genotype to scrapie, ARR/ARR, was found with the frequency lower than 0.180. The most susceptible genotype, VRQ/VRQ, was found in only Kıvırcık. The TRR and TRH alleles and the genotypes of ARR/TRR, ARR/ARK, and ARH/TRH have been found for the first time in Turkish native sheep breeds. According to these results, all breeds belong to risk group R3 followed by R2. It is propounded that the susceptibility to scrapie increased from eastern to western part of Turkey. Our findings of Turkish native sheep breeds with PrP gene polymorphisms will assist the sheep breeding program for selection of scrapie resistance genotypes to reduce the risk of scrapie.

Evaluation of the genetic resistance status to classical and atypicalscrapie in Karacabey merino rams

“…While the ARR allele, related to high resistance, is present at 28%, the VRQ allele, which is the most susceptible one, is only present at 0.43%. These data are compatible with those obtained from other Turkish native sheep breeds (15,(18)(19)(20)(21). With respect to their relevance to disease resistance/ susceptibility, PrP genotypes were classified into five groups from the most resistant (R1) to the most susceptible (R5) (7), as presented in Table 1.…”

Prion protein gene polymorphisms in classical scrapie-affected flocks of sheep in Central Macedonia

“…Higher frequencies of the ARQ allele have been reported in scrapie-affected sheep (Ekateriniadou et al, 2007a). Similar frequencies of the ARQ allele were reported in Italy (Granato et al, 2013, Martemucci et al, 2015, in Brazil (Ianella et al, 2012) and in Turkey (Meydan et al, 2012), whereas higher frequencies (74-86%) were observed in Awassi and Assaf sheep populations (Gootwine et al,2008).…”

“…This genotype is detected for the first time in Greece. Till now, it has been reported in Chinese Hu sheep (0.56%, F. Guan et al, 2011), in North Western China (0.40%, Zhao et al, 2012, in Turkey (0.1%, Meydan et al, 2012) and in Italy (1.7% in Foza breed, Granato et al, 2013). The very rare genotype ARK/VRQ was found only in Chios crossbred (0.31%) and the average frequency in the study population was 0.14%.…”

“…Furthermore, the ARQ allele and the ARQ/ARQ genotype were found to be the predominant allele and genotype respectively, in Finland (Hautaniemi et al, 2012), in China (Zhao et al, 2012), in Brazil (Ianella et al, 2012), in Turkey (Alvarez et al, 2011, Meydan et al, 2012, in East Asian sheep (Tsunoda et al, 2010) and in Pakistan (Babar et al, 2009) among other countries. Sheep with the genotype ARQ/ARQ are highly susceptible to scrapie, while this is the most common genotype among scrapie-affected sheep of Greek positive flocks with 68.35% in Chios crossbred, 70.39% in other crossbred (Ekateriniadou et al, 2007a), 72.73% (88 ARQ/ARQ fromin Chios crossbred).…”

“…Additional haplotypes (TRQ, ARK, VRR, AHR, VHQ and TRR) have been reported so far (Kutzer et al,2002, De Silva et al,2003, Acutis et al,2004, Billinis et al,2004, F. Guan et al,2011, Psifidi et al,2011, Oner et al,2011, Alvarez et al,2011, Zhao et al,2012, Meydan et al,2012, Granato et al,2013. According to the National Scrapie Plan for Great Britain, the fifteen most common genotypes have been classified into five risk groups (R1-R5), with R1 (ARR/ARR genotype sheep) indicating the lowest risk of scrapie and R5 (VRQ/VRQ, VRQ/ ARQ and other VRQ-encoding genotypes) associated with the highest susceptibility (DEFRA, 2001).…”