Nematode parasitism of arbovirus vectors: effect of mermithids on Culicoides biting midges and their potential use for disease and vector control

虫媒病毒载体的线虫寄生：拟虫对库蠓叮蠓的影响及其在疾病和媒介控制中的潜在用途

• 批准号: BB/N011937/1
• 负责人: Georgette Kluiters
• 金额: $ 36.17万
• 依托单位: University of Liverpool
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FN011937%2F1
• 关键词: Nematode; parasitism; arbovirus; vectors; effect

Biting midges are a group of tiny flying insects that include a notorious species that plagues parts of Scotland. They are one of the most abundant blood-feeding insects and occur throughout most of the inhabited world. Certain species commonly found on farms are important carriers of livestock viruses in Europe. Methods to control these insects have so far been unsuccessful.The emergence of the livestock diseases bluetongue (BT) in 2007 and Schmallenberg (SB) in 2011 in the UK highlight that midge transmitted viruses are a potential threat to the UK. They also spread African horse sickness (AHS), a highly lethal disease of horses, considered a risk to Europe. To date, over 50 viruses have been isolated from midges, causing significant economic impact through clinical disease and animal trade restrictions. Outbreaks of BT are ongoing in mainland Europe, so further outbreaks may occur in the UK. Currently we rely on vaccinating animals against some of these diseases, as control of insects transmitting them has been unsuccessful. Such vaccination is not routinely undertaken in UK livestock, and tends to only occur once an outbreak has been confirmed. Vaccines licensed for use in Europe do not exist for many diseases, including AHS and many types of BT. It is therefore paramount to determine other ways to manage such outbreaks to allow informed mitigation procedures in advance of, or in the event of, an outbreak.My aim is to investigate the effects of a highly prevalent parasitic worm (mermithid nematodes) on the biology of Culicoides midges and to determine whether they affect a midge's ability to be infected by and transmit livestock viruses. Mermithids are a major group of nematode that live inside the larvae of midges, and other insects, often killing them when they emerge; but may be carried into the adult insect, sterilizing them as a result. These mermithids are present in UK midges and the successful use of mermithids to control mosquito populations suggests that there may be potential in their use for midge control, yet no information exists on mermithid parasitism of these midge vectors in Europe.At the University of Liverpool, using Culicoides from across England and Wales, I aim to study the distribution of these nematodes and assess whether this changes between years. Despite their importance, very few mermithids have been successfully identified so I will use DNA-based techniques to determine the species parasitising UK midges, before establishing reliable identification techniques to enable other researchers to build on such work in the future. Any parasite which may be useful for Culicoides control must have an economical method of mass rearing, so a laboratory rearing method will be established and the possibility of storage and transportation determined, allowing field testing at a later date. Similar rearing methods have been successful in the USA, and this part of the project will be undertaken in collaboration with the University of California, Riverside. Most crucially, the effect of parasitism by mermithids will be assessed on the lifecycle, reproduction and fitness of the midges before being infected with BT and SB viruses and assessed for their ability to transmit virus, the dosage of virus needed to achieve infection, and their survival. Here both wild-caught and colony reared midges, supplied by the Pirbright Institute, will be infected with mermithids and virus at the Liverpool School of Tropical Medicine.This project will gather information relevant to a wide range of arthropod vectors, such as UK mosquitoes, as well as other humans and livestock vector-borne diseases. In the event of an outbreak the work may provide information for more effective vector control and will arm policy makers with information that can be useful for i) understanding methods to control midge-borne diseases; ii) reducing the chances of an outbreak occurring; iii) more effectively dealing with an outbreak occurrence.

蠓是一群微小的飞虫，其中包括一个臭名昭著的物种，困扰苏格兰部分地区。它们是最丰富的吸血昆虫之一，遍布世界上大部分有人居住的地方。农场中常见的某些物种是欧洲牲畜病毒的重要携带者。2007年英国出现的牲畜疾病蓝舌病（BT）和2011年英国出现的Schmallenberg（SB）突出表明，蠓传播的病毒是英国的潜在威胁。它们还传播非洲马瘟（AHS），这是一种高度致命的马匹疾病，被认为是欧洲的风险。迄今为止，已从蠓中分离出50多种病毒，通过临床疾病和动物贸易限制造成重大经济影响。BT的爆发正在欧洲大陆进行，因此英国可能会发生进一步的爆发。目前，我们依靠给动物接种疫苗来预防其中一些疾病，因为对传播这些疾病的昆虫的控制一直不成功。这种疫苗接种在英国牲畜中并不常规进行，并且往往仅在疫情被确认后才发生。在欧洲许可使用的疫苗并不存在于许多疾病中，包括AHS和许多类型的BT。因此，至关重要的是，以确定其他方式来管理这种疫情，让知情的缓解程序之前，或在发生的情况下，一个outbreak.My的目的是调查的影响，一个高度流行的寄生虫（索线虫）的生物学库蠓，并确定它们是否会影响一个蠓的能力，感染和传播牲畜病毒。索虫是一种主要的线虫，生活在蠓和其他昆虫的幼虫体内，经常在它们出现时杀死它们;但也可能被带入成虫体内，从而使它们绝育。这些mermithids是目前在英国的蠓和成功使用的mermithids控制蚊子种群表明，可能有潜力在其使用的蠓控制，但没有信息存在于mermithid寄生这些蠓vectors.At利物浦大学，使用库蠓从英格兰和威尔士，我的目标是研究这些线虫的分布，并评估这是否在几年之间的变化。尽管他们的重要性，很少mermithids已被成功地确定，所以我将使用基于DNA的技术来确定寄生英国摇蚊的物种，建立可靠的识别技术，使其他研究人员能够在未来的工作。任何可能对库蠓控制有用的寄生虫都必须有一种经济的大量饲养方法，因此将建立一种实验室饲养方法，并确定储存和运输的可能性，以便日后进行实地试验。类似的饲养方法在美国已经取得成功，该项目的这一部分将与加州大学滨江分校合作进行。最重要的是，在感染BT和SB病毒之前，将评估索虫寄生对摇蚊的生命周期、繁殖和适应性的影响，并评估它们传播病毒的能力、实现感染所需的病毒剂量以及它们的存活率。在利物浦热带医学院，由Pirbright研究所提供的野外捕获和群体饲养的蠓将被索线虫和病毒感染。该项目将收集与广泛的节肢动物媒介有关的信息，如英国蚊子，以及其他人类和牲畜媒介传播的疾病。在暴发的情况下，这项工作可以为更有效的病媒控制提供信息，并将为决策者提供有用的信息，以便i）了解控制蚊媒疾病的方法; ii）减少暴发发生的机会; iii）更有效地处理暴发事件。