Genetic predisposition of some Bulgarian sheep breeds to the scrapie disease

Abstract

The aim of this study is to investigate the profile of ovine PrP gene by amino acid polymorphism at codons 136, 141, 154, and 171 for determining the genetic predisposition to the Scrapie disease for the tribal sheep and rams, with different numbers and distribution in Bulgaria. Three hundred twenty four animals originating from 41 tribal herds comprising eight breeds were included in the study. DNA was isolated from blood samples specifically amplified by PCR and sequenced. The alignments of codons 136, 141, 154, and 171 were determined. Based on the sequencing, it was established that Bulgarian breeds belong to the second and third risk groups, those with low and moderate risk of Scrapie disease. Establishment of 11 genotypes in Synthetic Population Bulgarian Milk breed reveals it to have the highest risk of the Scrapie disease; moreover, the conducting of the program will be more difficult in comparison with other investigated breeds. Evidence for the internal cross breeding is the presence of the five or six genotypes in the Copper-Red Shoumen, Replian, Karakachan, and Duben Bulgarian native breeds.

Five Novel PRNP Gene Polymorphisms and Their Potential Effect on Scrapie Susceptibility in Three Native Ethiopian Sheep Breeds

“…Despite the long standing selective breeding programs in European countries, there has been no legalized selective breeding practices for scrapie in Bulgaria. A study reported ARQ and ARR as the predominant haplotypes among selected Bulgarian sheep flocks [40]. The high frequency of ARR could be due to the importation of resistant sheep from elsewhere.…”

Evaluation of Resistance and Susceptibility to Prion Diseases in Pelibuey Sheep from Mexico

“…The frequency for the VRQ allele found in Pelibuey breed herds is consistent with the frequencies in countries where the disease is absent, since there is no artificial selection based on this locus. ARR, which is associated with the highest resistance, has been found in Italy for sheep of the Sardinian breed (22), in other European vii breeds (33); in China sheep of the Hu breed (9) and in Bulgaria (30). Such high frequencies in countries with scrapie are because in these places they have already implemented the selection of animals carrying this allele.…”

“…All of the six alleles found in this work have already been reported previously. ARQ has been found in Italian sheep breeds (22); native sheep from Bulgaria (30), in China (9); in Turkey (31) and in Brazil, (32). VRQ, which is associated with the highest susceptibility to scrapie, has been observed in herds of the Italian Sarda breed (22); in native European sheep breeds (33); in Turkey (31) and in Brazil the absence of the allele is reported in some breeds (32).…”

Five novel PRNP gene polymorphisms and their potential effect on Scrapie susceptibility in three native Ethiopian sheep breeds

“…Despite the long standing selective breeding programs in European countries, there has been no legalized selective breeding practices for scrapie in Bulgaria. A study reported ARQ and ARR as the predominant haplotypes among selected Bulgarian sheep flocks [39]. The high frequency of ARR could be due to the importation of resistant sheep from elsewhere.…”