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: 7676743
• 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/7676743
• 关键词: Affect; Alphaproteobacteria; Animals; Applied Research; Arthropods; Bacteria; Bacteriophages; Biocontrols; Biology; Cell Culture Techniques; Cell Line; Cells; Coupled; 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; 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; 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是多细胞动物中最常见的专性细胞内细菌之一。通过在节肢动物中引起各种各样的生殖改变，有利于受感染的雌性的健康，这种细菌已经通过数十万种物种在世界范围内传播。沃尔巴克氏体的一个独特的基因组特征是移动的DNA过多，包括一个温和的双链DNA噬菌体，称为WO-B，没有已知的功能。我们的长期目标是阐明这种噬菌体对沃尔巴克氏体生物学的作用机制、相关性和应用。具体的假设是，噬菌体是沃尔巴克氏体的一种移动的遗传寄生物，能够整合到沃尔巴克氏体中并杀死沃尔巴克氏体，以确保其自身作为自私元素的复制。我们的假设基于四个观察：首先，WO-B是广泛的，感染了89%的所有菌株在两个主要的沃尔巴克氏体谱系感染节肢动物。第二，序列分析说明WO-B重组和水平传播之间的沃尔巴克氏体，共感染同一宿主。第三，WO-B的存在与诱导生殖改变的能力无关。第四，来自纯化的昆虫匀浆和来自裂解的沃尔巴克氏体细胞内的WO-B颗粒的观察表明WO-B是有活性的并且可以杀死沃尔巴克氏体。基于这些观察，本建议的实验重点是沃尔巴克氏体噬菌体WO-B的分子进化和捕食。具体目标是：1.确定形成沃尔巴克氏体噬菌体的分子进化力量。通过完成这个目标，我们将回答三个相关的问题：（目标1A）一个专性细胞内生态位如何影响噬菌体基因组进化？我们将确定专性细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。(Aim 1B）哪些类别的噬菌体基因正在被选择，它们与基因功能如整合、裂解、溶原性、毒力或结构相关吗？(Aim 1C）横向转移到沃尔巴克氏体合并感染和从沃尔巴克氏体合并感染转移的噬菌体基因的数量、多样性和功能是什么？我们的初步结果表明猖獗的水平噬菌体转移加上强大的纯化选择。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，我们将回答两个问题有关的噬菌体功能：（目的2A）在受控的实验室环境中，溶解性噬菌体捕食沃尔巴克氏体内共生体？(Aim 2B）环境应激是否触发噬菌体裂解，并且这种裂解的变化是否对应于沃尔巴克氏体密度的变化和与宿主的相互作用？我们提出这些subaims作为一种替代流行的观点，噬菌体可能是自适应沃尔巴克氏体的能力，修改节肢动物繁殖。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影响公共卫生，因为它增加了关于如何使用噬菌体的知识，（i）将转基因性状传播到节肢动物传播的载体中的管道，以及（ii）作为消除丝虫Wolbachia和相关人类病理的治疗工具