Murine Typhus: Vector Biology and Transmission

描述（由申请人提供）：我们提出的研究强调了几个主要的概念，如立克次体毒力问题，立克次体在不同脊椎动物和无脊椎动物宿主中的适应性问题，以及病原体-宿主（跳蚤/老鼠）相互作用的分子动力学。在这个竞争更新的应用程序中，我们建立在最近的成就，现在集中在解剖分子相关的定义鼠斑疹伤寒人畜共患病。因此，我们将采用包括立克次体基因组数据挖掘、病原体系统基因组分析和实证研究相结合的综合方法来调查立克次体和宿主转录组谱的模式，并确定宿主关联是否指导立克次体毒力的程度。这种竞争性更新的目的是：(1)确定跳蚤免疫反应蛋白是否限制斑疹伤寒的生长（Aim I）和(2)功能表征一组立克次体基因，这些基因被确定为在毒力中具有潜在作用（Aim II）。该提案的具体目标旨在突出宿主和立克次体为确保它们自己的生存而采用的策略。在目的一下，我们将检验跳蚤免疫反应蛋白限制斑疹伤寒生长的假设。为了揭示斑疹伤寒与每一种免疫反应蛋白在体内的相互作用，将采用免疫学、生化和分子方法来证明每一种免疫反应蛋白的共定位和抗立克次体特性。此外，RNAi将用于确定免疫基因表达的抑制是否会影响立克次体在体内的生长。在第二个目标下，我们将测试分泌蛋白在立克次体毒力中起主要作用的假设。为了评估这一假设，我们将采用一种综合的方法，包括全基因组鉴定和斑疹伤寒分泌蛋白的分子分析，以及通过反义RNA技术对选定的潜在毒力基因进行功能分析。项目叙述：鼠斑疹伤寒是一个很好的例子，它的重要性只有病人自己才能充分认识到，即使在今天，在世界上的大多数地方，他也永远不会知道是什么病，因为没有诊断。鼠（地方性）斑疹伤寒致病菌、斑疹立克次体、大鼠及其跳蚤之间的密切联系，是随着农村地区城市化程度的提高，这种疾病向农村社区蔓延的基础。因此，由于卫生条件松懈，斑疹伤寒不仅在世界许多沿海地区重新出现，而且在农村动物种群中成为一种新出现的病原体。本研究利用鼠斑疹伤寒动物模型，强调立克次体毒力和发病机制的几个主要概念。我们的研究通过提供病原体基因产物的信息来促进对斑疹伤寒生物学的理解，这些信息可用于开发更好的立克次体疫苗和/或治疗方法。

DESCRIPTION (provided by applicant): Our proposed research underscores several major concepts such as the issue of rickettsial virulence, rickettsial fitness in diverse vertebrate and invertebrate hosts, and molecular dynamics of pathogen-host (flea/rat) interactions. In this competing renewal application, we build upon recent accomplishments, and now focus on dissecting the molecular correlates that define the murine typhus zoonosis. Thus, we will use an integrated approach including the combination of rickettsial genome data mining, pathogen phylogenomic analysis and empirical studies to investigate the patterns of rickettsial and host transcriptome profiles and to define whether host-association directs the degree of rickettsial virulence. The aims of this competitive renewal is to (1) determine if flea immune response proteins limit the growth of R. typhi (Aim I) and (2) functionally characterize a set of rickettsial genes that were identified as having a potential role in virulence (Aim II). The specific aims of the proposal are designed to highlight the strategies employed by both the host and the Rickettsia typhi to ensure their own survival. Under the aim I, we will test the hypothesis that flea immune responsive proteins limit R. typhi growth. To implicate an interaction between R. typhi and each immune responsive protein in vivo, immunological, biochemical and molecular approaches will be used to demonstrate colocalization and anti-rickettsial properties of each immune responsive protein. Additionally, RNAi will be used to determine if suppression of immune gene expression affects rickettsial growth in vivo. Under the second aim we will test the hypothesis that secretory proteins play a cardinal role in rickettsial virulence. In order to assess this hypothesis, we will utilize an integrated approach that includes a genome-wide identification and molecular analysis of R. typhi secretory proteins and functional analysis of selected potential virulence genes by anti-sense RNA technology. PROJECT NARRATIVE: Murine typhus is a good example of a disease whose importance is not adequately appreciated except by the patient, and, even today, in most parts of the world, he will never know what ails him because the diagnosis will not be made. An intimate association between the causative agent of murine (endemic) typhus, Rickettsia typhi, rats and their fleas underlie the expansion of this disease into rural communities as the urbanization of rural settings is on the increase. Thus, R. typhi not only re-emerge in many coastal regions of the world as a result of relaxed hygiene but also become an emerging pathogen in rural animal populations. Our proposed research underscores several major concepts in rickettsial virulence and pathogenesis by using murine typhus animal model. Our research advances the understanding the biology of R. typhi by providing information on pathogen gene products that could be used in developing better rickettsial vaccines and/or therapeutics.