Department of Animal and Veterinary Science, University of Idaho, Moscow, ID, 83844, USA.
USDA, ARS, Dale Bumpers Small Farms Research Center, Booneville, AR, 72927, USA.
Anim Genet. 2020 Mar;51(2):330-335. doi: 10.1111/age.12895. Epub 2020 Jan 3.
Resistance to gastrointestinal nematodes has previously been shown to be a moderately heritable trait in some breeds of sheep, but the mechanisms of resistance are not well understood. Selection for resistance currently relies upon faecal egg counts (FEC), blood packed cell volumes and FAMACHA visual indicator scores of anaemia. Identifying genomic markers associated with disease resistance would potentially improve the selection process and provide a more reliable means of classifying and understanding the biology behind resistant and susceptible sheep. A GWAS was conducted to identify possible genetic loci associated with resistance to Haemonchus contortus in Katahdin sheep. Forty animals were selected from the top and bottom 10% of estimated breeding values for FEC from a total pool of 641 sires and ram lambs. Samples were genotyped using Applied Biosystems™ Axiom™ Ovine Genotyping Array (50K) consisting of 51 572 SNPs. Following quality control, 46 268 SNPs were included in subsequent analyses. Analyses were conducted using a linear regression model in plink v1.90 and a single-locus mixed model in snp and variation suite. Genome-wide significance was determined by a Bonferroni correction for multiple testing. Using linear regression, loci on chromosomes 2, 3, 16, 23 and 24 were significantly associated at the genome level with FEC estimated breeding values, and we identified a region on chromosome 2 that was significant using both statistical analyses. We suggest a potential role for the gene DIS3L2 for gastrointestinal nematode resistance in Katahdin sheep, although further research is needed to validate these findings.
先前的研究表明，在某些绵羊品种中，对胃肠道线虫的抗性具有中度的遗传性，但对其抗性机制仍了解甚少。目前，对抗性的选择依赖于粪便卵计数（FEC）、血液红细胞压积和 FAMACHA 贫血视觉指标评分。鉴定与疾病抗性相关的基因组标记可能会改善选择过程，并提供更可靠的方法来分类和理解抗性和易感绵羊的生物学。进行了全基因组关联研究（GWAS），以鉴定与卡他丁绵羊感染捻转血矛线虫抗性相关的可能遗传位点。从 641 只公羊和公羊羔羊的总群体中，根据 FEC 的估计育种值，从上 10%和下 10%中选择了 40 只动物。使用 Applied Biosystems™ Axiom™ 绵羊基因分型阵列（50K）（包含 51,572 个 SNP）对样品进行基因分型。经过质量控制后，有 46,268 个 SNP 包含在后续分析中。使用 plink v1.90 中的线性回归模型和 snp 和变异套件中的单基因座混合模型进行分析。通过对多重测试进行 Bonferroni 校正来确定全基因组显著性。使用线性回归，染色体 2、3、16、23 和 24 上的位点与 FEC 估计育种值在全基因组水平上显著相关，我们使用两种统计分析都确定了染色体 2 上的一个显著区域。我们建议 DIS3L2 基因在卡他丁绵羊的胃肠道线虫抗性中可能具有潜在作用，尽管需要进一步研究来验证这些发现。
