Department of Animal Sciences, University of Florida, Gainesville, FL.
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL.
J Anim Sci. 2019 Nov 4;97(11):4428-4444. doi: 10.1093/jas/skz299.
The aim of this study was to identify for the first time single nucleotide polymorphisms (SNPs) associated with Haemonchus contortus resistance in Florida Native sheep, using a targeted sequencing approach. One hundred and fifty-three lambs were evaluated in this study. At the start of the trial, phenotypic records for fecal egg count (FEC), FAMACHA score, body condition score (BCS), and weight were recorded and deworming of sheep with levamisole (18 mg/kg of body weight) was performed. Ten days post-deworming (baseline) and 28 d post-baseline, a full hematogram of each sheep was obtained and FEC, FAMACHA score, BCS, and weight were assessed. Average daily gain was calculated at the end of the trial. Out of 153 animals, 100 sheep were selected for genotyping using a targeted sequencing approach. Targeted sequencing panel included 100 candidate genes for immune response against H. contortus. SNPs were discarded if call rate <95% and minor allele frequency ≤0.05. A mixed model was used to analyze the response variables and included the identity by state matrix to control for population structure. A contemporary group (age, group, and sex) was included as fixed effect. Bonferroni correction was used to control for multiple testing. Eighteen SNPs on chromosomes 1, 2, 3, 4, 6, 7, 11, 15, 18, 20, 24, and 26 were significant for different traits. Our results suggest that loci related to Th17, Treg, and Th2 responses play an important role in the expression of resistant phenotypes. Several genes including ITGA4, MUC15, TLR3, PCDH7, CFI, CXCL10, TNF, CCL26, STAT3, GPX2, IL2RB, and STAT6 were identified as potential markers for resistance to natural H. contortus exposure. This is the first study that evaluates potential genetic markers for H. contortus resistance in Florida Native sheep.
本研究旨在首次利用靶向测序方法鉴定与佛罗里达本地绵羊感染捻转血矛线虫抗性相关的单核苷酸多态性（SNP）。本研究共评估了 153 只羔羊。在试验开始时，记录了粪便卵计数（FEC）、FAMACHA 评分、体况评分（BCS）和体重的表型记录，并对绵羊用左旋咪唑（18mg/kg 体重）进行了驱虫。驱虫后 10 天（基线）和基线后 28 天，对每只绵羊进行全血计数，并评估 FEC、FAMACHA 评分、BCS 和体重。试验结束时计算平均日增重。在 153 只动物中，有 100 只绵羊被选为使用靶向测序方法进行基因分型。靶向测序面板包括 100 个候选基因，用于针对捻转血矛线虫的免疫反应。如果等位基因调用率<95%且次要等位基因频率≤0.05，则会丢弃 SNP。使用混合模型分析响应变量，并包括状态矩阵以控制群体结构。将当代组（年龄、组和性别）作为固定效应包括在内。使用 Bonferroni 校正控制多重检验。在第 1、2、3、4、6、7、11、15、18、20、24 和 26 号染色体上的 18 个 SNP 对不同性状具有显著意义。我们的结果表明，与 Th17、Treg 和 Th2 反应相关的基因座在抗性表型的表达中发挥重要作用。包括 ITGA4、MUC15、TLR3、PCDH7、CFI、CXCL10、TNF、CCL26、STAT3、GPX2、IL2RB 和 STAT6 在内的几个基因被确定为对天然捻转血矛线虫感染的抗性的潜在标记物。这是首次评估佛罗里达本地绵羊感染捻转血矛线虫抗性的潜在遗传标记的研究。
