Molecular basis for spotted fever group Rickettsia vector competence in ticks

蜱中斑疹热群立克次体载体能力的分子基础

• 批准号: 8109931
• 负责人: Kevin R. Macaluso
• 金额: $ 36.26万
• 依托单位: LOUISIANA STATE UNIV A&M COL BATON ROUGE
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-20 至 2014-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8109931
• 关键词: Adhesions; Amblyomma; Binding Proteins; Biological; Biological Assay; Competence; Dermacentor; Ecology; Epidemiology; Event; Fever; Fluorescent in Situ Hybridization; Generations; Genetic Transcription; Goals; Health; Horizontal Disease Transmission; Human; Immune; Individual; Infection; Kinetics; Laboratories; Mediating; Modeling; Molecular; Nature; Pathogenicity; Protein Binding; Proteins; RNA; Rickettsia; Rickettsia Infections; Rickettsia rickettsii; Role; Route; Specificity; Spottings; Testing; Tick Infestations; Tick-Borne Diseases; Ticks; Time; Tissues; Translating; United States; Vertical Disease Transmission; Virulence; antimicrobial; base; comparative; fitness; in vivo; in vivo Bioassay; in vivo Model; interest; novel strategies; pathogen; prevent; protein protein interaction; receptor; transmission process; vector

DESCRIPTION (provided by applicant): Rickettsia rickettsii is the causative agent of one of the most severe tick-borne diseases in the United States. The compounding factors of rickettsial pathogenicity and route of tick transmission (horizontal and vertical) influence the ecology and epidemiology of human rickettsioses. Our long term goal is to elucidate the molecular mechanisms that are central to rickettsial transmission by ticks. Despite the overlapping distribution of ticks with multiple Rickettsia species in nature, individual tick species are not infected with a diverse range of rickettsial species. Therefore, the broad hypothesis being tested is that unique tick-derived factors are required for successful horizontal and vertical transmission of spotted fever group (SFG) Rickettsia. Preliminary evidence indicates rickettsial transmission is dependent on the appropriate tick/Rickettsia relationship and the pathogenic nature of the Rickettsia. It is also known that ticks actively respond to the infecting rickettsiae; however, the extent to which modulation of tick-derived molecules is required for rickettsial survival within the tick is not known. Thus, the experimental focus of this proposal is to delineate the specificity of tick/Rickettsia relationships, the relationship between rickettsial pathogenicity and transmission, and to define the tick-derived molecules associated with rickettsial infection via comparative analysis of different tick and Rickettsia species. The previously undefined parameters of tick/Rickettsia interactions will be determined in the following specific aims. 1) Characterize the horizontal and vertical transmission of pathogenic and nonpathogenic SFG Rickettsia in tick hosts in vivo. The previously unknown kinetics of transmission for six species of SFG Rickettsia will be assessed in Amblyomma and Dermacentor ticks. Horizontal transmission of rickettsiae from Rickettsia-infected ticks to vertebrate hosts will be determined using a laboratory model of tick infestation. The efficiency of vertical transmission of Rickettsia will be assessed by fluorescence in situ hybridization and quantitative real-time PCR (qPCR) and the influence of SFG Rickettsia carriage on tick fitness will be assessed. 2) Examine the interaction between tick-derived molecules and SFG Rickettsia during infection in typical and atypical tick/Rickettsia relationships. Protein-protein interaction assays will be used to identify rickettsial binding proteins present in whole tick tissues. Studies will utilize paired tick tissues and SFG rickettsiae in comparative pull-down and protein binding assays. We will identify key tick proteins and delineate their role in the establishment of Rickettsia via bioassays including adhesion/invasion blocking assays, immune/antimicrobial activity assessment, and RNA-mediated interference (RNAi). The utilization of specific molecules by individual species of Rickettsia will also be assessed. PUBLIC HEALTH RELEVANCE Despite the overlapping distribution of ticks with multiple Rickettsia species, in nature, individual tick species are not infected with a diverse range of rickettsial species. We will examine the specificity of tick/Rickettsia relationships and delineate the molecular mechanisms of tick vector competence for spotted fever Rickettsia to better understand the ecology and epidemiology of tick-borne rickettsial diseases.

描述（由申请人提供）：立克人士立克西ii是美国最严重的tick传播疾病之一的病因。立克疾病的致病性和壁虱传播途径（水平和垂直）的复合因素影响人体力学的生态学和流行病学。我们的长期目标是阐明tick虫的立克传播至关重要的分子机制。尽管自然界中有多个立克物种的壁虱分布重叠，但单个tick物种并未感染各种ricketsial物种。因此，被检验的广泛假设是，斑点发烧组（SFG）人力素的成功水平和垂直传播需要独特的tick衍生因素。初步证据表明，立克的传播取决于适当的tick虫/立克的关系和立克的致病性。众所周知，壁虱会积极回应感染的立克西亚。然而，尚不清楚tick中立克生存需要的tick衍生分子的调节程度尚不清楚。因此，该提案的实验重点是描述tick/立克人际关系的特异性，立克的致病性和传播之间的关系，并通过对不同tick虫物种的比较分析来定义与立克感染相关的tick衍生的分子。以下特定目的将确定先前未定义的参数。 1）表征体内tick宿主中的致病性和非对病毒性SFG人力素的水平和垂直传播。以前未知的SFG人力素性物种的传播动力学将在Amblyomma和Dermacentor Ticks中进行评估。将使用tick侵染的实验室模型确定Rickettsiae从立克感染的滴答脊椎动物的水平传播。人力体的垂直传播的效率将通过原位杂交和定量实时PCR（QPCR）评估，并评估SFG Rickettsia托架对TICK适应性的影响。 2）检查在典型和非典型的tick/人力体关系中，在感染过程中，tick衍生的分子与SFG人力车之间的相互作用。蛋白质 - 蛋白质相互作用测定将用于鉴定整个壁虱组织中存在的立克结合蛋白。研究将在比较下拉和蛋白质结合测定中利用配对的tick组织和SFG立克西亚。我们将确定关键的tick蛋白，并通过生物测定法中描绘出它们在立克的建立中的作用，包括粘附/侵袭阻断测定，免疫/抗菌活性评估和RNA介导的干扰（RNAI）。还将评估利克西亚各个物种对特定分子的利用。公共卫生相关性尽管有多种立克斯山的壁虱分布重叠，但在本质上，单个tick物种并未感染各种ricketsial物种。我们将研究tick/立克人际关系的特异性，并描绘出斑点发烧人力车的tick矢量能力的分子机制，以更好地了解tick传播的立克疾病的生态学和流行病学。