Hunter N, Moore L, Hosie B D, Dingwall W S, Greig A
Institute for Animal Health, BBSRC/MRC Neuropathogenesis Unit, Edinburgh.
Vet Rec. 1997 Jan 18;140(3):59-63. doi: 10.1136/vr.140.3.59.
The incidence of natural scrapie in sheep is associated with polymorphisms of the PrP gene, particularly those at codons 136, 154 and 171. In many breeds, the PrP allele encoding valine at codon 136 confers an extremely high risk of scrapie, but in Suffolk sheep this allele is vanishingly rare. In this study of a single closed flock of Suffolk sheep in Scotland, scrapie occurred primarily in animals which were homozygous for glutamine at codon 171, a genotype which was significantly less frequent in healthy flockmates. However, the apparent linkage between glutamine at codon 171 and scrapie was not completely recessive because two of 64 scrapie cases were heterozygous glutamine/arginine. These results suggest that breeding for increased resistance to scrapie in Suffolks by the selection of animals according to their PrP genotype is a feasible option.
绵羊自然感染羊瘙痒病的发病率与PrP基因的多态性有关，特别是密码子136、154和171处的多态性。在许多品种中，编码密码子136处缬氨酸的PrP等位基因会带来极高的羊瘙痒病风险，但在萨福克羊中，这种等位基因极为罕见。在这项对苏格兰一个单一封闭萨福克羊群的研究中，羊瘙痒病主要发生在密码子171处为谷氨酰胺纯合子的动物身上，这种基因型在健康的同群羊中频率显著较低。然而，密码子171处的谷氨酰胺与羊瘙痒病之间的明显关联并非完全隐性，因为64例羊瘙痒病病例中有2例是谷氨酰胺/精氨酸杂合子。这些结果表明，根据PrP基因型选择动物来培育对羊瘙痒病抵抗力增强的萨福克羊是一个可行的选择。
