Resistance in Agriculture: Investigation of Anthelmintic Drug Uptake and Resistance Mechanisms in Gastrointestinal Nematode Parasites of Livestock.

寄生线虫是人类和家畜的重要病原体，可引起慢性衰弱性疾病。线虫是放牧家畜常见的重要经济病原体，在世界范围内普遍存在。自由生活阶段是采取了牧场和致病阶段最终发现在胃肠道。这些寄生虫在英国各地很常见。报告的临床爆发的数量和这些寄生虫的地理范围正在增加，其中一个因素是我们日益温暖和潮湿的气候延长了自由生活阶段的生存。这些寄生虫的控制严重依赖于数量有限的驱虫剂，估计每年绵羊养殖业的成本超过8400万英镑。驱虫药伊维菌素是控制这些常见寄生线虫的主要药物，这种药物对控制动物和重要人类线虫感染的重要性最近得到了2015年诺贝尔奖的认可，该奖项授予了发现它的研究人员。正如BBSRC的农业抗性呼吁所承认的那样，驱虫药抗性现在变得普遍，原因有很多，包括过度应用。现在还报告了对不同类别药物的多重耐药性，迫切需要了解这种耐药性的确切性质，以保持其余化合物的功效。对伊维菌素和其他类驱虫药的耐药性以及实际上的多药耐药性代表了困扰英国和全球畜牧业的一个真实的且不断加深的危机，这可能最终成为人类医学中的一个问题，其中IVM也是发展中国家大规模人群蠕虫控制计划的关键组成部分。伊维菌素的作用模式已得到充分表征，但对该药物的实际耐药机制知之甚少。本提案旨在通过多学科方法了解伊维菌素耐药性、对其他驱虫药类别的耐药性和多药耐药性的性质。我们的假设，根据我们的初步数据，指出，干扰IVM摄取是产生广泛耐药性的关键。我们提出，线虫的“鼻子”的神经元回路的解剖学变化与对这种药物的耐药性有关。我们认为，类似的机制可能是负责苯并咪唑，左旋咪唑和Monepantel类的结构distince药物，并可能确实涉及我们在该领域看到的多药耐药。我们计划证明这一假设，从而更深入地了解药物如何进入线虫，如何产生耐药性，如何监测和控制耐药性的传播，以及最终如何开发新的，更有效的驱虫剂，同时延长我们现有药物的“保质期”。这一建议将增加我们对寄生线虫的基本知识，寄生线虫是全球畜牧业严重经济损失的主要原因。这项工作的一部分将在良好表征的、遗传学上适合的模型系统秀丽隐杆线虫中进行，从而减少我们实验中动物的使用。这一建议的时机是重要的，因为技术和工具（下一代测序的C。线虫突变体和关键寄生线虫的完整基因组）现在可用于解决这些重要病原体中的抗性性质。有效治疗家畜线虫感染还将在英国提供经济和环境可持续的农业，最终有助于维护英国的粮食安全。使用多学科的方法来应对抗性带来的挑战，使这项工作成为农业抗性呼吁的理想选择。

The parasitic nematodes are important pathogens of man and domestic animals that can cause chronic debilitating diseases. The trichostrongylid nematodes represent common and economically important pathogens of grazing livestock and have a worldwide prevalence. The free-living stages are taken up with pasture and pathogenic stages are ultimately found in the gastro-intestinal tract. These parasites are common throughout the United Kingdom. The numbers of reported clinical outbreaks and the geographic range of these parasites are increasing, with a contributing factor being our increasingly warmer and wetter climate prolonging the survival of the free-living stages. Control of these parasites is heavily dependent on a limited number of anthelmintics and is estimated to cost the sheep farming industry in excess of £84 million per annum. The anthelmintic drug ivermectin is a mainstay for control of these common parasitic nematodes, and the importance of this drug to control both animal and important human nematode infections was recently recognised by the award of a Nobel Prize in 2015 to the researchers who discovered it. As recognised by the BBSRC's Resistance in Agriculture Call, anthelmintic resistance is now becoming commonplace due a number of factors, including over-application. Multiple resistance to different classes of drugs has now also been reported and there is an urgent requirement to understand the precise nature of this resistance in order to preserve the efficacy of the remaining compounds. Resistance to ivermectin and other classes of anthelmintic and indeed multidrug resistance represent a real and deepening crisis afflicting the UK and global livestock rearing industry and this may ultimately become a problem in human medicine where IVM is also a key component of large population-wide worm control programmes in the developing world. The mode of action of ivermectin is well characterized but very little is known about the actual resistance mechanism to this drug. This proposal aims to understand the nature of both ivermectin resistance, resistance to other anthelmintic classes and multidrug resistance using a multidisciplinary approach. Our hypothesis, based on our preliminary data, states that disruption of IVM uptake is key to generation of widespread resistance. We propose that anatomical changes in neuronal circuitry of the nematode's "nose" is linked to resistance to this drug. We propose that similar mechanisms may be responsible for the structurally distince drugs of the Benzimadazole, Levamisole and Monepantel classes and may indeed be involved in multidrug resistance that we see in the feild. We plan to prove this hypothesis and therefore develop a deeper understanding of how drugs get into nematodes, how resistance occurs, how the spread of resistance can be monitored and controlled, and finally how we can develop new, more effective anthelmintics while extending the "shelf-life" of our currently available drugs. This proposal will increase our basic knowledge of parasitic nematodes that are a major cause of serious economic losses to livestock farming industries worldwide. A proportion of this work will be carried out in the well-characterised, genetically-amenable model system, Caenorhabditis elegans, thereby reducing the use of animals in our experiments. The timing of this proposal is important as the technology and tools (next generation sequencing of C. elegans mutants and well completed genomes of the key parasitic nematodes) are now available to address the nature of resistance in these important pathogens. Treating nematode infections effectively in livestock will also provide economically and environmentally sustainable agriculture in the UK that will ultimately help maintain the UK's food security. Using a multidisciplinary approach to address the challenge posed by resistance makes this work an ideal fit for the Resistance in Agriculture Call.