Ovine prion protein genotype frequencies in northwestern China

Abstract

ABSTRACT. Anti-scrapie breeding programs have been initiated to screen for scrapie-resistant sheep based on ovine prion protein gene (PRNP) genotypes at codons 136, 154 and 171 in many countries, especially European Union member states. However, investigation of sheep PRNP genotypes is limited in China, despite the large number of sheep breeds. We analyzed 432 sheep of five different breeds from farms in northwestern China, using PCR-single-strand conformational polymorphism analysis (PCR-SSCP); the corresponding haplotypes of different PRNP alleles were cloned. PRNP allele genotyping was done by amplification refractory mutation system-PCR (ARMS-PCR), according to the haplotype clones of each PRNP allele. The validity of ARMS-PCR was checked by PCR-SSCP. Another 325 unknown PRNP genotypes of other sheep breeds were analyzed according to the established ARMS-PCR. Genotype frequencies of 757 sheep were analyzed with these two methods to evaluate susceptibility to scrapie in northwestern China. Relevant mutations were also detected at other sites. Both methods were effective for ovine PRNP allele genotyping, and the results of the analysis completely coincided. Scrapie-resistant genotypes were found to be uncommon, indicating a high risk for ovine scrapie in northwest China. In addition to codons 136, 154 and 171, we found numerous new mutations; nearly half of them were previously unreported. These sheep populations have a high degree of polymorphism at the PRNP locus.

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

“…This genotype has also been observed in Chinese Hu sheep, (9.44%, F. Guan et al, 2011), in Northwestern China (0.53%, Zhao et al, 2012) and in Turkey (4.03%, Oner et al, 2011& 6.0%, Alvarez et al, 2011. The rare genotype TRQ/ARH was found only in Chios crossbred and in Chios breed and the frequencies were 0.63% and 0.88% respectively, at a mean of 0.48%.…”

“…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).…”

Research Article The correlation analysis of polymorphisms of Prion-Related Doppel (PRND) with prion (PRNP) alleles in Gansu Alpine Merino sheep

“…The susceptibility of scrapie was affected by the polymorphism of PRNP alleles, 136, 154 and 171 (González and Martin et al, 2002). The scrapie-susceptibility alleles of ARQ in sheep population accounted for a large proportion in China (Zhao and Wu et al, 2012). Although the polymorphism of PRND codon 174 loci associated with human sporadic Creutzfeld-Jakob (CJD) (Croes and Alizadeh et al, 2004), PRND genotype and the correlation analysis of polymorphisms of PRND with PRNP is still unclear.…”

Expression patterns of Doppel in differential ovine PRNP genotypes: quantification using real-time RT-PCR

“…Two types of prevalent heterozygous genotype were studied in healthy Small-tailed Han sheep in Gansu Province of China (Zhao et al, 2012). Four ewes were ARR/ARQ, a genotype resistant to scrapie (Caplazi et al, 2004), and four ewes were ARH/ARQ, a genotype with intermediate susceptibility to scrapie (O'Doherty et al, 2002).…”