新疆地区绵羊品种朊蛋白基因136、154和171位点的多态性

绵羊痒病是一种渐进性和致死性中枢神经系统疾病,绵羊朊蛋白基因(Prion protein gene,PRNP)多态性与痒病的易感或抗性有关,其中PRNP136位(V/A)、154位(H/R)和171位(H/Q/R)的基因多态性与该病发生最相关。为评价新疆地区主要绵羊品种对痒病的易感性,文章对新疆地区10个绵羊品种(阿勒泰、巴士拜、巴音布鲁克、多浪、和田、策勒黑、中国美利奴、德国肉用美利奴、特克赛尔和萨福克羊)共746只个体PRNP基因的136位(V/A)、154位(H/R)和171位(H/Q/R)的遗传多态性进行分析,检测到了ARQ、ARR、ARH、ARK、VRQ、AHR、AHQ、AHH8种等位基因,其中ARQ和ARR等位基因存在于所有品种中,且ARQ在所有品种中的基因频率最高。ARH存在于除萨福克和德国肉用美利奴羊外的8个绵羊品种中。仅在新疆地方品种阿勒泰、巴音布鲁克、巴士拜和多浪羊中检测到ARK等位基因。而VRQ、AHR、AHQ和AHH4种等位基因只在中国美利奴羊上存在,且频率极低。在10个品种中共检测到了ARQ/ARQ、ARQ/ARK、ARR/ARR、ARH/ARH、ARQ/ARR、ARH/ARQ、ARH/ARR、ARK/ARK、ARH/ARK、ARQ/VRQ、ARQ/AHQ、ARQ/AHR和ARH/AHH13种基因型,其中中度易感的ARQ/ARQ基因型频率最高,而抗性最强的ARR/ARR基因型仅存在于巴音布鲁克、策勒黑、中国美利奴、特克赛尔和德国肉用美利奴羊,且频率较低。文章首次在中国美利奴羊上发现了易感性很强的VRQ/ARQ基因型。上述结果提示新疆的主要绵羊品种对痒病的抗性较弱。

Polymorphism at codons 136, 141 and 154 in the ovine prion protein gene in the state of Xinjiang

Scrapie is a fatal and infectious neurodegenerating disease. The polymorphism in the prion protein (PRNP) gene is linked to the development of clinical signs of scrapie. The most important polymorphism appears to be at codons at 136(V/A), 154(H/R), and 171(H/Q/R). In this study, we investigated the polymorphisms at these codons in 746 individuals among ten sheep breeds (i.e., ALeTai, BaShiBai, BaYinBuLuKe, Celehei, DuoLang, He Tian, Chinese Merino, German Merino, Texel, and Suffolk sheep) in Xinjiang in order to evaluate the relative susceptibility of sheep to scrapie. A total of 8 alleles (i.e., ARQ, ARR, ARH, ARK, VRQ, AHR, AHQ and AHH) were observed. The alleles ARQ and ARR were found in all of the breeds with the highest frequency for allele ARQ. Allele ARH was found in eight breeds except for Suffolk and German Merino, while the ARK was only identified in ALeTai, BaShiBai, BaYinBuLuKe, and DuoLang native sheeps. The alleles VRQ, AHR, AHQ and AHH were detected exclusively in Chinese Merino with extremely low frequencies. Moreover, the genotypes contained by the eight alleles were also determined subsequently. A total of thirteen genotypes, such as ARQ/ARQ, ARQ/ARK, ARR/ARR, ARH/ARH, ARQ/ARR, ARH/ARQ, ARH/ARR, ARK/ARK, ARH/ARK, ARQ/VRQ, ARQ/AHQ, ARQ/AHR and ARH/AHH were detected. The genotype ARQ/ARQ with moderate susceptibility was found with the highest frequency among the ten breeds, whereas the genotype ARR/ARR with highest resistance to scrapie was merely identified in BaYinBuLuKe, Celehei, Chinese Merino, Texel and German Merino sheep, which had very low frequencies. In addition, the genotype VRQ/ARQ with high susceptibility was first variant reported in Chinese Merino sheep. Our data, therefore, indicate that the general genetic resistance of dominating sheep breeds in Xinjiang to scrapie was considerably low.