Introgression of ivermectin resistance genes into a susceptible Haemonchus contortus strain by multiple backcrossing.
Introgression of ivermectin resistance genes into a susceptible Haemonchus contortus strain by multiple backcrossing.
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DOI：
10.1371/journal.ppat.1002534
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发表时间：
2012-02
期刊：
影响因子：
6.7
通讯作者：
Gilleard JS
中科院分区：
文献类型：
--
作者：
Redman E;Sargison N;Whitelaw F;Jackson F;Morrison A;Bartley DJ;Gilleard JS
牲畜寄生虫对驱虫虫的耐药性已经很普遍，近年来，人类寄生虫种群面临的驱虫虫药物选择压力越来越大，导致人们对耐药性的出现感到担忧。然而，大多数寄生线虫，特别是人类的寄生线虫，是困难的实验对象，使得耐药性的机制研究极其困难。小反刍动物弓形血线虫是研究寄生虫生物学和研究驱虫耐药的基本机制和遗传学的一个更合适的模型系统。在这里，我们报道了通过回交方法将两个独立的伊维菌素耐药菌株MHco4（WRS）和MHco10（CAVR）的伊维菌素耐药基因成功导入易感基因组参考菌株MHco3（ISE）中。一组微卫星标记物用于监测整个过程。通过18个微卫星位点的整体基因分型和9个微卫星位点的亚组个体基因分型，研究人员发现，经过4轮回交后，对伊维菌素产生表型抗性的线虫与敏感参考菌株具有相似的遗传背景。此外，单个标记Hcms8a20显示了与伊维菌素耐药位点的遗传联系，为更详细地研究该基因组区域以确定致病突变提供了起点。这项工作提出了一种新的遗传方法来研究驱虫虫的抗性，并提供了在与人类钩虫相关的一个重要模型中使用正向遗传学的“概念证明”。所得到的菌株为候选基因研究、全基因组方法和进一步的遗传分析鉴定伊维菌素耐药位点提供了宝贵的资源。使用药物（驱虫药）控制线虫寄生虫（蛔虫）在人类和动物中都很常见。这导致牲畜寄生虫普遍产生耐药性，并对人类寄生虫出现耐药性表示严重关切。扭曲血线虫是一种易产生耐药性的绵羊寄生线虫，是目前应用最广泛的驱虫耐药性研究模型系统。伊维菌素是控制人类和动物寄生虫的一种极其重要的药物。在这里，我们报告了一种新的方法，利用遗传杂交将H. contortus基因组中含有伊维菌素抗性基因的区域从耐药菌株转移到易感菌株中。在我们的回交方法中，我们已经确定了一个遗传标记，显示与伊维菌素耐药性有遗传联系的证据。我们使用的易感菌株目前正在进行完整的基因组测序，这使得这里产生的信息和菌株对鉴定伊维菌素耐药基因非常有价值。这项工作为利用遗传方法鉴定寄生线虫中含有耐药基因的基因组区域提供了一个重要的概念证明。
Anthelmintic drug resistance in livestock parasites is already widespread and in recent years there has been an increasing level of anthelmintic drug selection pressure applied to parasitic nematode populations in humans leading to concerns regarding the emergence of resistance. However, most parasitic nematodes, particularly those of humans, are difficult experimental subjects making mechanistic studies of drug resistance extremely difficult. The small ruminant parasitic nematode Haemonchus contortus is a more amenable model system to study many aspects of parasite biology and investigate the basic mechanisms and genetics of anthelmintic drug resistance. Here we report the successful introgression of ivermectin resistance genes from two independent ivermectin resistant strains, MHco4(WRS) and MHco10(CAVR), into the susceptible genome reference strain MHco3(ISE) using a backcrossing approach. A panel of microsatellite markers were used to monitor the procedure. We demonstrated that after four rounds of backcrossing, worms that were phenotypically resistant to ivermectin had a similar genetic background to the susceptible reference strain based on the bulk genotyping with 18 microsatellite loci and individual genotyping with a sub-panel of 9 microsatellite loci. In addition, a single marker, Hcms8a20, showed evidence of genetic linkage to an ivermectin resistance-conferring locus providing a starting point for more detailed studies of this genomic region to identify the causal mutation(s). This work presents a novel genetic approach to study anthelmintic resistance and provides a “proof-of-concept” of the use of forward genetics in an important model strongylid parasite of relevance to human hookworms. The resulting strains provide valuable resources for candidate gene studies, whole genome approaches and for further genetic analysis to identify ivermectin resistance loci. The use of drugs (anthelmintics) to control nematode parasites (roundworms) is common in both humans and animals. This has led to the widespread development of drug resistance in livestock parasites and serious concerns regarding its emergence in human parasites. Haemonchus contortus is a parasitic nematode of sheep that has a high propensity to develop resistance and is the most widely used model system in which to study anthelmintic drug resistance. Ivermectin is an extremely important drug for parasite control in both humans and animals. Here, we report a novel approach using genetic crossing to transfer a region of the H. contortus genome containing ivermectin resistance genes from resistant strains into a susceptible strain. During our backcrossing approach, we have identified a genetic marker showing evidence of genetic linkage to ivermectin resistance. The susceptible strain we have used is currently having its complete genome sequenced making the information and strains generated here extremely valuable for the identification of ivermectin resistance genes. This work represents an important proof of concept for using genetic approaches to identify genomic regions containing drug resistant genes in parasitic nematodes.
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影响因子：
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作者：
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通讯作者：
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von Samson-Himmelstjerna, G.
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