Prion Protein Polymorphisms and Estimation of Risk of Scrapie in East Asian Sheep

Abstract

Allele and genotype frequency distributions of prion protein (PrP) polymorphisms at three codons, 136, 154, and 171, in East Asian sheep were determined by PCR-RFLP analysis using 553 animals from nine local breeds of the northern group and four local breeds of the southern group. Based on the genotype distribution, the risk score for scrapie was estimated. Among the local breeds, ARQ appeared predominantly (0.7701-1), followed by ARH and ARR. From such a biased allele distribution, it was difficult to ascertain the prevalent genetic relationships. A marked difference in allele frequencies between the northern and southern groups was seen (P < 0.0001). The East Asian sheep had ARQ at the highest frequency (0.8834); in European sheep it was 0.5317. According to an assessment of scrapie risk in the PrP genotype classes, the predominant ARQ/ARQ in East Asian sheep corresponded to the risk score of R4. This finding suggests that East Asian sheep have a high level of genetic susceptibility to scrapie.

PrP genotype frequencies and risk evaluation for scrapie in dairy sheep breeds from southern Italy

“…This study reports the PrP genotype frequencies of the southern Italian indigenous Apulian Altamurana and Leccese and allochthonous Comisana dairy sheep breeds. The ARQ, representing the ancestral form of the PrP gene (Drögemüller et al, 2001), was the most frequent allele in all the sheep populations studied (36.5-59.5%), in agreement with previous works in other countries involving different breeds (Alvarez et al, 2006;Tsunoda et al, 2010;Meydan et al, 2012). Higher frequencies of ARQ were found in the Lec and Altamurana compared to the Com breed.…”

Assessment of the Genetic Susceptibility of Sheep to Scrapie by Protein Misfolding Cyclic Amplification and Comparison with Experimental Scrapie Transmission Studies

“…Accordingly, PMCA detected no evident amplification using ARQ/ ARR and ARR/ARR genotypes. Recent studies indicate that some rare PrP variant may also confer protection from classical scrapie (47,50), and this is of particular interest for scrapie control strategies, taking into consideration the existence of sheep breeds in which the ARR allele is rare or absent (1,46) and the potential risk deriving from the selection in favor of a single allele. The control of scrapie in goats, which do not have the ARR allele, also represents a challenge for health policies, given that two BSE cases have been detected so far in goats (15,26).…”

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

“…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).…”