Amino Acid Polymorphisms of PrP Gene in Mongolian Sheep.

Abstract

ABSTRACT. To characterize amino acid polymorphisms in sheep prion protein (PrP), we analyzed the PrP genes from 271 sheep of 4 breeds (Khalkh, Yeroo, Orkhon and Khangai) raised in central Mongolia (Tuv, Uvurkhangai and Selenge prefectures). A total of 16 genoty pes and 8 allelic variants of the PrP gene at codons 112, 136, 154 and 171 were found. At codon 171, 1.8% of the sheep had arginine/arginine (R/R) (resistant to scrapie) and 66.8% had glutamine/glutamine (Q/Q) (susceptible to scrapie). Several Yeroo and Orkhon sheep raised in Selenge prefecture had valine at codon 136 (136V) (highly susceptible to scrapie). Several Yeroo, Orkhon and Khangai sheep raised in Selenge prefecture had histidine at codon 154 (154H). Novel polymorphisms of valine (V) and serine (S) at codon 127, lysine (K) at codon 171, and leucine (L) and arginine (R) at codon 189 were also found in Khalkh, Yeroo and Orkhon sheep. It is not known whether these novel polymorphisms affect scrapie susceptibility.

Unique Amino Acid Polymorphisms of PrP Genes in Mongolian Sheep Breeds

“…In this study, the relative genotype frequencies of four codons (112, 136, 154, and 171) of the PrP gene are newly reported in five sheep breeds (Sartuul, Govi-altai, Bayad, Darhad, and Sumber Karakul), in addition to four previously reported sheep breeds (Khalkh, Yeroo, Orkhon, and Khangai) [6]. Table 1 shows the genotype frequencies of 16 different PrP genotypes in the 740 sheep examined.…”

“…However, in central Asian countries where many sheep are raised, the polymorpism of PrP genes associated with scrapie have not yet been characterized. Therefore, we examined the PrP genotypes of 740 Mongolian sheep, including 271 sheep previously reported [6].…”

“…1. ); 60 Khalkh sheep from Uvurkhangai prefecture (J); and 35 Yeroo sheep, 35 Orkhon sheep, and 29 Khangai sheep from Selenge prefecture (K) [6]. [6].…”

“…The entire 794-bp open reading frame (ORF) of the PrP gene was amplified by polymerase chain reaction (PCR) in 50 µl reactions, using PrP primers (SPrP-1, SPrP-2, SPrP-3, and SPrP-5) as described by Gombojav et al [6]. To confirm amplification, a portion of each reaction product was electrophoresed on a 0.7% agarose gel containing ethidium bromide (0.5 µg/ml), and visualized under ultraviolet radiation.…”

“…To confirm amplification, a portion of each reaction product was electrophoresed on a 0.7% agarose gel containing ethidium bromide (0.5 µg/ml), and visualized under ultraviolet radiation. Then, the primers were removed using a Centricon 100 micro-concentrator (Amicon, Bedford, MA), and 1 to 5 µl of the concentrated PCR product was used for direct sequencing [6].…”