Molecular Evolution and Life Cycle of Wolbachia Bacteriohage

沃尔巴克氏菌噬菌体的分子进化和生命周期

• 批准号: 7506517
• 负责人: SETH R BORDENSTEIN
• 金额: $ 24.56万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7506517
• 关键词: Affect; Alphaproteobacteria; Animals; Applied Research; Arthropods; Bacteria; Bacteriophages; Biocontrols; Biology; Cell Line; Cells; Class; Condition; Coupled; Cultured Cells; Cytolysis; DNA; Development; Disease; Disease Vectors; Elements; Ensure; Environment; Equilibrium; Evolution; Female; Gene Deletion; Gene Pool; Genes; Genetic; Genetic Recombination; Genetic Variation; Genome; Genomics; Goals; Health; Horizontal Disease Transmission; Horizontal Gene Transfer; Human; Human Pathology; In Vitro; Infection; Insecta; Investigation; Knowledge; Laboratories; Lateral; Life; Life Cycle Stages; Life Style; Lysogeny; Lytic; Molecular; Molecular Biology; Molecular Evolution; Mutation; Numbers; Organism; Parasites; Phase; Planets; Population; Predatory Behavior; Public Health; Reproduction; Research; Role; Sequence Analysis; Shapes; Specific qualifier value; Stress; Stress Tests; Structure; System; Testing; Therapeutic; Thinking; Time; Transgenic Organisms; Variant; Virion; Virulence; Wolbachia; base; comparative; density; ds-DNA; egg; experience; extracellular; fitness; functional genomics; gene function; genome sequencing; in vivo; insect disease; killings; obligate intracellular parasite; particle; reproductive; theories; tool; trait; transposon/insertion element; vector

DESCRIPTION (provided by applicant): Wolbachia pipientis is one of the most prevalent obligate, intracellular bacteria in multicellular animals. By causing a diverse array of reproductive alterations in arthropods that favor the fitness of infected females, this bacterium has spread worldwide through hundreds of thousands of species. One of the unique genomic features to Wolbachia is an overabundance of mobile DNA including a temperate double-stranded DNA bacteriophage, called WO-B that has no known function. Our long term goal is to elucidate the mechanisms, relevance, and applications of this bacteriophage to the biology of Wolbachia. The specific hypothesis is that the bacteriophage is a mobile genetic parasite of Wolbachia, capable of integrating into and killing Wolbachia to ensure its own replication as a selfish element. We base that hypothesis on four observations: First, WO-B is widespread and infects 89% of all strains in the two major Wolbachia lineages that infect arthropods. Second, sequence analyses specify WO-B recombination and horizontal transmission between Wolbachia that co-infect the same host. Third, the presence of WO-B does not correlate with the capacity to induce reproductive alterations. Fourth, observations of WO-B particles from purified insect homogenates and from within lysed Wolbachia cells demonstrate that WO-B is active and may kill Wolbachia. Based on these observations, the experimental focus of this proposal is on the molecular evolution and predation of Wolbachia phage WO-B. The specific aims are to: 1. Determine the molecular evolutionary forces shaping Wolbachia bacteriophage. By completing this aim, we will answer three related questions: (Aim 1A) How does an obligate intracellular niche affect phage genome evolution? We will determine how the distinctive ecological conditions of an obligate intracellular bacterium affect genetic diversity in WO-B and we will compare this to the rules of phage genome evolution in free-living bacteria. (Aim 1B) What classes of phage genes are under selection and do they correlate with gene functions such as integration, lysis, lysogeny, virulence, or structure? (Aim 1C) What are the number, diversity, and functions of phage genes that laterally transfer to and from Wolbachia co-infections? Our preliminary results suggest rampant horizontal phage transfer coupled with strong purifying selection. 2. Determine if bacteriophage kill Wolbachia and thereby regulate intrahost densities and Wolbachia's effects on hosts. Here, we will answer two questions related to phage function: (Aim 2A) In a controlled laboratory environment, do lytic phages prey on Wolbachia endosymbionts? (Aim 2B) Does environmental stress trigger phage lysis and does this variation in lysis correspond to variation in Wolbachia densities and interactions with the host? We propose these subaims as an alternative to the prevailing view that phage may be adaptive to Wolbachia's ability to modify arthropod reproduction. Our preliminary studies suggest their principal role is predation of Wolbachia. PROJECT NARRATIVE: The study of Wolbachia pipientis phage may impact public health by increasing knowledge on how to employ the phage as (i) a conduit for spreading transgenic traits into arthropod-borne vectors and (ii) as a therapeutic tool for removing filarial Wolbachia and associated human pathologies

描述（由申请人提供）：Wolbachia pipientis 是多细胞动物中最普遍的专性细胞内细菌之一。通过在节肢动物中引起一系列有利于受感染雌性健康的生殖改变，这种细菌已在全世界数十万个物种中传播。沃尔巴克氏体的独特基因组特征之一是过量的可移动 DNA，其中包括一种温和的双链 DNA 噬菌体，称为 WO-B，其功能尚不清楚。我们的长期目标是阐明这种噬菌体在沃尔巴克氏体生物学中的机制、相关性和应用。具体假设是，噬菌体是沃尔巴克氏体的一种可移动的遗传寄生虫，能够整合并杀死沃尔巴克氏体，以确保其作为自私元素的自身复制。我们的假设基于四个观察结果：首先，WO-B 分布广泛，感染节肢动物的两个主要沃尔巴克氏体谱系中 89% 的所有菌株。其次，序列分析明确了共同感染同一宿主的沃尔巴克氏体之间的 WO-B 重组和水平传播。第三，WO-B的存在与诱导生殖改变的能力无关。第四，对来自纯化的昆虫匀浆和裂解的沃尔巴克氏体细胞内的WO-B颗粒的观察表明，WO-B具有活性并且可以杀死沃尔巴克氏体。基于这些观察，本提案的实验重点是沃尔巴克氏菌噬菌体WO-B的分子进化和捕食。具体目标是： 1. 确定塑造沃尔巴克氏菌噬菌体的分子进化力量。通过完成这一目标，我们将回答三个相关问题：（目标 1A）专性细胞内生态位如何影响噬菌体基因组进化？我们将确定专性胞内细菌的独特生态条件如何影响 WO-B 中的遗传多样性，并将其与自由生活细菌中噬菌体基因组进化的规则进行比较。 （目标 1B）哪些类型的噬菌体基因正在被选择，它们是否与整合、裂解、溶源、毒力或结构等基因功能相关？ （目标 1C）横向转移至沃尔巴克氏体共感染或从沃尔巴克氏体共感染中转移的噬菌体基因的数量、多样性和功能是多少？我们的初步结果表明，水平噬菌体转移猖獗，加上强烈的纯化选择。 2. 确定噬菌体是否杀死沃尔巴克氏体，从而调节宿主内密度和沃尔巴克氏体对宿主的影响。在这里，我们将回答与噬菌体功能相关的两个问题：（目标 2A）在受控的实验室环境中，裂解噬菌体会捕食沃尔巴克氏体内共生体吗？ （目标 2B）环境压力是否会引发噬菌体裂解？裂解的这种变化是否对应于沃尔巴克氏体密度的变化以及与宿主的相互作用？我们提出这些子目标作为流行观点的替代方案，即噬菌体可能适应沃尔巴克氏体改变节肢动物繁殖的能力。我们的初步研究表明它们的主要作用是捕食沃尔巴克氏体。 项目叙述：对 Wolbachia pipientis 噬菌体的研究可能会通过增加有关如何使用噬菌体作为（i）将转基因特性传播到节肢动物传播载体的渠道和（ii）作为消除丝虫 Wolbachia 和相关的人类病理学