The Enterocytozoonidae: the emergence of a microsporidian clade into the aquatic and terrestrial food-chain

微孢子虫是一组超过1000种描述的寄生微生物，其物种在所有环境中感染所有主要动物谱系。一个特别重要的微孢子虫科是肠胞虫科。这是一个有趣的群体，其成员感染水生和陆生栖息地的宿主。它包括两个引人注目的成员：比氏肠细胞虫（Enterocytozoon bieneusi），这是艾滋病相关腹泻的最常见原因之一，以及虎虾病原体肝细胞虫（Enterocytozoon hepatopenaei）。后者与虾生长严重迟缓有关，给水产养殖业数百万人造成相当大的经济损失。此外，E.最近已经证明，hepatopenaei已经跳跃宿主，在可食用的白虾中引起严重的疾病。肠胞虫科，尤其是肠胞虫E. hepatopenaei，鉴于其新兴的经济重要性，需要进一步的研究，这个学生的目的是使用环境DNA来解决以下两个问题，在肠细胞虫科生物学：学生的第一个目标是回答如何E的问题。在亚洲的虾养殖场中传播。虽然最初报道来自泰国，E。在中国、印度尼西亚、马来西亚、越南和印度也发现了hepatopenaei。这种传播可能是由受感染的虾从一个农场到另一个农场的移动介导的，或者感染可能是从中间宿主和/或受污染的饲料中获得的。该项目建议使用分子数据来确定传播是如何发生的，从而为水产养殖政策提供信息，以防止进一步传播。最近，拟议的项目合作伙伴之间的合作工作已经产生了E。目前正用于设计更好的诊断PCR引物，以了解病原体的流行。本项目拟通过对E.从泰国的多个地理位置、中国以及Whiteleg和Tiger虾宿主中收集了肝衰竭病毒。生成的分子数据将用于重建菌株之间的进化关系，并推断地理位置和宿主之间的运动。第二个目标是解决环境中存在多少未发现的肠细胞虫科寄生虫的问题。人和虾是肠胞虫科的两个重要宿主，两者都可能从尚未鉴定的中间宿主获得这些感染。该项目的这一组成部分旨在查明重要的肠细胞虫科的宿主或携带者以及可能有能力引起人类或动物疾病的其他物种。我们将从人类和水生动物种群交界处的环境中收集无脊椎动物样本，例如，生活污水，河流，河口和沿海栖息地以及泰国的虾池。然后，我们将从所有这些生物体沿着提取DNA以及它们相关的寄生虫的DNA，并使用最先进的基因测序技术对样本中每种寄生虫的相同基因进行测序。通过研究基因序列的多样性，我们可以识别原始样本中存在的微孢子虫寄生虫。当我们检测到我们感兴趣的病原体（E。bieneusi和E.我们将标记扩增的DNA序列，并将其用作探针来确定中间宿主的身份。拟议的工作将作为以下人员的合作进行监督：Bryony威廉姆斯（埃克塞特大学）将提供基因组学和分子工作的设备、培训和专业知识; CASE合作伙伴Grant Stentiford（CEFAS）将提供样本收集、实地工作和中间宿主识别方面的培训; Kallaya Dangtip和Ornchuma Itsathiphaisarn（泰国玛希隆大学虾分子生物学和生物技术卓越中心），该中心将提供虾和虾塘样品。

Microsporidia are a group of over 1000 described parasitic microbes with species infecting all major animal lineages in all environments. One particularly important family of microsporidia are the Enterocytozoonidae. This is an intriguing group with members that infect hosts from both aquatic and terrestrial habitats. It includes two high profile members: Enterocytozoon bieneusi, which is one of the most common causes of AIDS-associated diarrhoea and the tiger shrimp pathogen Enterocytozoon hepatopenaei. The latter is associated with severely retarded shrimp growth, which results in considerable economic losses for millions of people in the aquaculture industry. Additionally, E. hepatopenaei has recently been shown to have jumped host causing severe disease in the edible Whiteleg Shrimp. The Enterocytozoonidae, and particularly E. hepatopenaei, given its emerging economic importance, need further study and this studentship aims to use environmental DNA to address the following two questions in Enterocytozoonidae biology:The first aim of the studentship is to answer the question of how E. hepatopenaei has spread across shrimp farms in Asia. Though initially reported from Thailand, E. hepatopenaei has also been found in China, Indonesia, Malaysia, Vietnam and India. This transmission may be mediated by movement of infected shrimp from farm to farm, or the infection may be acquired from intermediate hosts and/or contaminated feed. This project proposes to use molecular data to determine how transmission has occurred and therefore inform aquaculture policies to prevent further spread. Recent collaborative work between the proposed project partners has generated genome sequence data for E. hepatopenaei which is currently being used to design better diagnostic PCR primers to understand the prevalence of the pathogen. This project proposes to expand this work by sequencing genomes of E. hepatopenaei collected from multiple geographic locations in Thailand, from China and from both Whiteleg and Tiger shrimp hosts. The generated molecular data will be used to reconstruct evolutionary relationships between the strains and infer movement between geographic localities and hosts. The second aim addresses the question of how many undiscovered Enterocytozoonidae parasites are present in the environment. Humans and shrimps are two important hosts for the Enterocytozoonidae and both may be acquiring these infections from, as yet, unidentified intermediate hosts. This component of the project aims to identify reservoirs or carriers for important Enterocytozoonidae and further species that may have the capacity to cause human or animal disease. We will collect invertebrate samples from environments at the interface of human and aquatic animal populations, for example, domestic sewage, riverine, estuarine and coastal habitats and from shrimp ponds in Thailand. We will then extract the DNA from all these organisms along with that of their associated parasites and use state of the art gene sequencing technology to sequence the same gene for each parasite in the sample. By studying the diversity of the gene sequences we can identify the microsporidian parasites present in the original sample. When we detect our pathogens of interest (E. bieneusi and E. hepatopenaei) or close relatives of these, we will label the amplified DNA sequences and use these as probes to determine the identity of intermediate hosts.The proposed work will be supervised as a collaboration between: Bryony Williams (University of Exeter) who will provide will provide equipment, training and expertise for genomics and molecular work; CASE partner Grant Stentiford (CEFAS) who will provide training in sample collection, fieldwork and identification of intermediate hosts; Kallaya Dangtip and Ornchuma Itsathiphaisarn (Center of Excellence for Shrimp Molecular Biology and Biotechnology, Mahidol University, Thailand) who will provide shrimp and shrimp pond samples.