Scrapie resistance gene identification using optimized TaqMan test qPCR method in sheep on the territory of the Republic of Serbia

Abstract

Scrapie is an infectious neurodegenerative disease affecting the central nervous system of sheep and goats that belongs to transmissible spongiform encephalopathies. The disease is caused by the accumulation of proteinase-resistant isoform of the prion protein. The sheep predisposition to scrapie is associated with polymorphisms of the PrP gene. Genetic susceptibility to scrapie is mainly related to codons 136, 154, and 171. ARR sheep are strongly scrapie resistant and VRQ genotype is the most susceptible. Many countries have scrapie eradication programs based on using rams with resistant genotype. The eradication program has not yet been implemented in the Republic of Serbia. To examine the genetic makeup of sheep in Serbia related to scrapie, we optimized TaqMan probes of real-time polymerase chain reaction (qPCR) technique for three codons. Blood samples from 100 sheep were analyzed by qPCR and the majority of the examined sheep were AA homozygous for the 136 codon. For codon 154 the most frequent genotype was RR and for codon 171 the most frequent genotype was QQ.

Ovčija svrabež je infektivno neurodegenerativno oboljenje iz grupe transmisivnih encefalopatija koje uzrokuje promene u moždanom tkivu ovaca i koza. Oboljenje je uzrokovano akumulacijom proteinaza-rezistentne izoforme prion proteina. Osetljivost ovaca na ovo oboljenje uslovljena je polimorfi zmom PrP gena. Genetska otpornost na ovčiju svrabež prevashodno je uslovljena kodonima 136, 154 i 171. Najotpornije su ovce sa ARR genotipom, dok se ovce sa VRQ genotipom smatraju najosetljivijim. Mnoge zemlje su sprovele programe eradikacije ovčije svrabeži bazirane na korišćenju priplodnih ovnova koji imaju rezistentan genotip. Ovakav program još nije sproveden u Republici Srbiji. U cilju ispitivanja genetskog statusa ovaca u Srbiji u pogledu otpornosti na ovčiju svrabež, optimizovali smo TaqMan probu, kvantitativne lančane reakcije polimeraze (qPCR) tehnike za sva tri kodona. Ispitivanjem uzoroka krvi od 100 ovaca primenom RT-PCR ustanovljeno je da je većina ovaca AA homozigot za kodon 136. Za kodon 154 najčešći genotip je RR, a za kodon 171 genotip QQ.