Genetic and molecular basis of triclabendazole resistance in Fasciola hepatica

片形吸虫病是一种常见和重要的牲畜疾病，给畜牧业造成重大经济损失。它是由肝吸虫肝片吸虫引起的，肝片吸虫是一种在肝脏中发现的扁虫，通过泥蜗牛传播。在英国，这是与反刍动物消化道相关的最常见的感染。肝芽胞杆菌的未成熟阶段会导致急性疾病，这对动物福利有负面影响，对绵羊通常是致命的。片形虫病主要通过药物治疗来控制，最常用的药物是三氯咪唑（TCBZ）。这是唯一一种对致病性早期未成熟阶段有效的药物。它也是由同一种寄生虫引起的人类片形吸虫病的首选药物。1995年首次在澳大利亚报告了对TCBZ的耐药性，现在在世界许多地方报告了耐药性。对肝念珠菌的耐药机制了解甚少。该提案旨在解决这一问题以及耐药性中的其他悬而未决的问题，例如：TCBZ耐药性是一种遗传途径还是多种遗传途径？哪些因素影响肝吸虫群体中耐药等位基因的出现和传播？该项目将利用我们之前非常成功的项目的成果，该项目产生了肝梭菌基因组草图，并定位（绘制）了TCBZ抗性寄生虫基因组的区域，这可能解释了它们在药物治疗中存活的能力。在这里，我们将制作一些测序资源来改进这种映射练习，包括；a)改进基因组组织的连锁图谱；b)对自然感染耐药寄生虫的绵羊粪便中的吸虫卵进行全基因组测序，在TCBZ治疗前后进行测序。分析这些序列将使我们能够接近负责编码TCBZ抗性的基因或基因，并将帮助我们了解抗性如何从一代寄生虫传递到下一代。为了帮助鉴定相关基因，我们将抗性和易感克隆寄生虫暴露于TCBZ，并表征总基因表达谱和化学指纹图谱（全球代谢组学谱）。在项目结束时，我们将有耐药性的遗传标记，可用于检测和跟踪在英国自然感染羊和牛的肝杆菌群体中出现的耐药性。该项目还将为更广泛的科学界提供其他重要产出，例如基因组、转录组和代谢组数据库。我们将把所有这些资源提供给全世界的肝吸虫研究人员；这样，我们就能在未来更有效地控制这种寄生虫。

Fasciolosis is a common and important disease of livestock that results in substantial economic losses to the livestock sector. It is caused by the liver fluke, Fasciola hepatica, a flatworm found in the liver and transmitted via a mud snail. In the UK it is the most commonly reported infection associated with the digestive tract of ruminants. The immature stages of F. hepatica are responsible for acute disease, which has a negative impact on animal welfare and is often fatal in sheep. Fasciolosis is controlled predominantly using drug treatment and the most commonly used drug is triclabendazole (TCBZ). This is the only drug that is effective against the pathogenic early immature stages. It is also the drug of choice for human fasciolosis, caused by the same parasite. Resistance to TCBZ was first reported in Australia in 1995 and is now reported in many locations worldwide. Little is known about the mechanisms of drug resistance in F. hepatica. This proposal aims to address this and other outstanding questions in drug resistance such as: Is there one genetic route to TCBZ resistance or multiple? What factors influence the emergence and spread of drug resistance alleles in liver fluke populations?This project will utilise outputs from our highly successful previous project, which produced a draft F. hepatica genome and located (mapped) areas of the genome of TCBZ resistant parasites that may explain their ability to survive drug treatment. Here, we will produce a number of sequencing resources to improve this mapping exercise, including; a) a linkage map to improve the organisation of the genome and b) whole-genome sequencing of fluke eggs from the faeces of sheep naturally infected with resistant parasites, from before and after TCBZ treatment. Analysing these sequences will allow us to close in on the gene or genes responsible for encoding TCBZ resistance and will help us understand how resistance is passed from one parasite generation to the next. To assist in identifying the genes involved we will expose our resistant and susceptible clonal parasites to TCBZ and characterise the total gene expression profile and chemical fingerprint (global metabolomic profile). At the end of the project we will have genetic markers for resistance that can be used to detect and track the emergence of resistance in populations of F. hepatica naturally infecting sheep and cattle in the UK. There will be other important outputs for the wider scientific community from the project, such as a bank of genomic, transcriptomic and metabolomic data. We will make all these resources available to liver fluke researchers worldwide; so that, together, we can more effectively control this parasite in future.