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

Ün³

2020

Preprint

Section: Resultssupporting

confidence: 82%

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

Ün³

2020

Preprint

“…As in previous studies, non synonymous and synonymous substitutions i.e. G127G, S138S, R231R, L237L, G126A, 126GA, 127GV, 127GA, 142IT, N146S and N146NS were also identified in the population under study [10][11][12]. In the present study, the variant at codon 127 in particular was highly In countries such as Canada and Czech Republic, where scrapie was once apparently prevalent, the resistant haplotype ARR, became dominant over the previously reported VRQ and ARQ haplotypes [4,24,25].…”

Section: Discussionsupporting

confidence: 83%

“…An earlier study linked the AC 151 RQ genotype to a prolonged incubation period after scrapie exposure [7]. Similarly, several studies reported variants such as G126A, G126G, G127G, G127V, G127A and S138S [10][11][12] in sheep prion protein with or without direct effect to scrapie susceptibility.…”

Section: Introductionmentioning

confidence: 92%

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

Ün³

2020

Preprint

Background Classical scrapie susceptibility in sheep has been linked to three polymorphisms at codon 136, 154, and 171 in the prion protein gene ( PRNP) whereas atypical scrapie susceptibility is related to polymorphisms at position 141. Many other variants over the length of the PRNP have been reported. Some of the variants may play crucial roles in fighting against the emergence of a new form of scrapie disease. Scrapie surveillance, scrapie associated genotyping and PRNP characterization studies have been conducted across the globe. However, such in-depth studies have never addressed the African continent’s sheep breeds. Therefore, genotyping native Ethiopian sheep breed’s PRNP gene has socioeconomic and scientific merits. This study aimed to identify PRNP variants in three native Ethiopian sheep breeds and their potential effect on scrapie susceptibility. Results Five novel variants were identified in the PRNP gene of three native Ethiopian sheep breeds. Four non-synonymous heterozygous substitutions i.e. H99Q (CAC-->CAA), H99L (CAC-->CTA), A116E (GCA-->GAA), A116T (GCA-->ACA) and one synonymous N103N (AAC-->AAT) were detected. In addition to the novel variants, polymorphisms at codon 126,127,138,142,146,231 and 237 were also identified. The haplotype ARR was observed in Menz and Afar breeds at frequencies of 0.02 and 0.05 respectively. Neither ARR/ARR nor VRQ/VRQ genotypes were identified in the population under study. Conclusion Two of the novel variants at codon 99 and 103 that are placed closer to the proteinase K cleavage site and the variant at codon 116 in the palindrome region along with variants at codon 127 in glycine repeat domain may influence the conformational flexibility of prion protein. The rarity of ARR haplotype and the abundance of 141L variant demonstrated that the present study population was less resistant to classical scrapie and less predisposed to genotype associated atypical scrapie. This study provides a valuable dataset that can be potentially integrated into selective breeding strategies during interbreeding, crossbreeding and help to take precautionary measures against scrapie. Keywords: Ethiopian sheep; Novel Variations; Polymorphism; Prion gene; Scrapie Susceptibility

“…An earlier study linked genotypes such as AC 151 RQ to prolonged incubation period after scrapie exposure [10]. Together with that, several studies reported polymorphisms such as G126A, G126G, G127G, G127V, G127A, and S138S [3][4][5][6] in sheep prion protein with or without direct effect to susceptibility to scrapie.…”

mentioning

confidence: 84%

Novel Variations at Three Different Positions of Prion Protein Coding Gene in Ethiopian Sheep Breeds and the Resistance/Susceptible Status to Classical and Atypical Scrapie

Ün³

2019

Preprint

Background: Classical Scrapie susceptibility in sheep has been linked to three polymorphisms at positions 136, 154, and 171 in the PRNP gene whereas atypical scrapie susceptibility is related to a polymorphism at position 141. Many other variants over the length of the prion protein coding gene were reported. Since infectious prion protein itself seems to be polymorphic, the identified novel PRNP gene variations may play a crucial role in fighting against the emergence of a new form of scrapie disease. Many studies conducted around the world to identify disease resistant status and new variants of PRNP gene in different breeds. However, such in-depth studies have never addressed the African continent’s sheep breeds. Therefore, genotyping native Ethiopian sheep breeds PRNP gene provides essential information to the current knowledge. This study aimed to identify potential novel variations in the Ethiopian sheep PRNP gene, thereby determine the uniqueness of the native breeds and predict scrapie status of sheep population based on the genotypes distribution. Results : Five novel variants were identified in the PRNP gene of native Ethiopian sheep. Four non-synonymous heterozygous substitutions at H99Q (CAC-->CAA), H99L (CAC-->CTA), A116E (GCA-->GAA), A116T (GCA-->ACA), and one synonymous N103N (AAC-->AAT) variants were detected. In addition to the novel variations, polymorphisms at 126,127,138,142,146,231, and 237 positions were also identified. The haplotype ARR was observed only in Menz and Afar breeds with frequencies 0.02 and 0.05 respectively. However, neither ARR/ARR nor VRQ/VRQ genotypes were identified in all of the breeds. Conclusion: Two of the novel variations at position 99 and 103 that are placed closer to the cleavage site and variant at 116 spotted in the palindrome region along with variants at position 127 in Glycine repeat domain may influence the conformational flexibility of prion protein. The low frequency of ARR haplotype and the sole variant 141L demonstrated that Ethiopian sheep are susceptible to classical scrapie and resistant to atypical scrapie. This study provides a valuable dataset that can be potentially integrated into selective breeding strategies against scrapie during inbreeding, crossbreeding and help to take precautious measures.