Sayers G, Good B, Hanrahan J P, Ryan M, Angles J M, Sweeney T
Department of Animal Husbandry and Production, Faculty of Veterinary Medicine, UCD, Dublin 4.
Parasitology. 2005 Sep;131(Pt 3):403-9. doi: 10.1017/s0031182005007778.
A potential control strategy for nematode infection in sheep is the implementation of a breeding programme to select for genes associated with resistance. The Texel breed is more resistant to gastrointestinal nematode infection than the Suffolk breed, based on faecal egg count, and this difference should enable the identification of some of the genes responsible for resistance. The objective of this study was to determine if variation at the ovine MHC-DRB1 locus was associated with variation in faecal egg count in Suffolk and Texel sheep. Ovar-DRB1 alleles and faecal egg count were determined for Texel (n = 105) and Suffolk (n = 71) lambs. Eight Ovar-DRB1 alleles, including 1 previously unknown allele, were identified in the Texel breed by sequence-base-typing. Seven Ovar-DRB1 alleles were identified in the Suffolk breed. Two Ovar-DRB1 alleles were common to both breeds, but were among the least frequent in the Suffolk population. In the Suffolk breed 1 Ovar-DRB1 allele was associated with a decrease in faecal egg count and 2 alleles with an increase in faecal egg count. This locus accounted for 14% of the natural variation in faecal egg count in Suffolks. There was no evidence for an association between Ovar-DRB1 alleles and faecal egg count in the Texel breed and the Ovar-DRB1 locus accounted for only 3% of the phenotypic variation in faecal egg count. These results suggest that the Ovar-DRB1 gene plays an important role in resistance to nematode infection in the Suffolk breed. The difference in faecal egg counts between these breeds may be attributable in part to the different allele profile at the Ovar-DRB1 locus.
绵羊线虫感染的一种潜在控制策略是实施一项育种计划，以选择与抗性相关的基因。基于粪便虫卵计数，特克塞尔品种比萨福克品种对胃肠道线虫感染更具抗性，这种差异应有助于识别一些负责抗性的基因。本研究的目的是确定绵羊MHC-DRB1基因座的变异是否与萨福克和特克塞尔绵羊粪便虫卵计数的变异相关。测定了特克塞尔（n = 105）和萨福克（n = 71）羔羊的Ovar-DRB1等位基因和粪便虫卵计数。通过序列分型在特克塞尔品种中鉴定出8个Ovar-DRB1等位基因，包括1个先前未知的等位基因。在萨福克品种中鉴定出7个Ovar-DRB1等位基因。两个Ovar-DRB1等位基因在两个品种中都有，但在萨福克群体中频率最低。在萨福克品种中，1个Ovar-DRB1等位基因与粪便虫卵计数减少相关，2个等位基因与粪便虫卵计数增加相关。该基因座占萨福克粪便虫卵计数自然变异的14%。没有证据表明特克塞尔品种中Ovar-DRB1等位基因与粪便虫卵计数之间存在关联，且Ovar-DRB1基因座仅占粪便虫卵计数表型变异的3%。这些结果表明，Ovar-DRB1基因在萨福克品种对线虫感染的抗性中起重要作用。这些品种之间粪便虫卵计数的差异可能部分归因于Ovar-DRB1基因座的不同等位基因谱。
