Arthropod host-dependent influence on rickettsial pathogenicity

节肢动物宿主依赖性对立克次体致病性的影响

• 批准号: 8728407
• 负责人: Kevin R. Macaluso
• 金额: $ 34.53万
• 依托单位: LOUISIANA STATE UNIV A&M COL BATON ROUGE
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-09 至 2015-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8728407
• 关键词: Accounting; Africa South of the Sahara; Arthropods; Benign; Biological; Biological Assay; Blood; Characteristics; Deposition; Disease; Environment; Epidemiology; Eukaryota; Event; Evolution; Felis catus; Fever; Fleas; Gene Targeting; Genetic Transcription; Genus Felis; Goals; Horizontal Disease Transmission; Human; Infection; Inherited; Insecta; Intervention; Maintenance; Mediating; Molecular; Molecular Profiling; Nature; Pathogenicity; Peptides; Population; RNA; Relative (related person); Rickettsia; Rickettsia Infections; Rickettsia felis; Role; Route; Salivary Glands; Signal Transduction; System; Testing; Ticks; Transcript; United States; Vertical Disease Transmission; Virulence; Virulent; base; comparative; feeding; fitness; in vivo; microorganism; pathogen; public health relevance; reproductive; response; transcriptome sequencing; transmission process; vector

DESCRIPTION (provided by applicant): Rickettsia felis was originally identified in the United States as a human pathogen in 1991; and, with increased recognition worldwide, it is now realized that human infections caused by R. felis account for up to 6% of the causes of fever among non-malarial conditions in sub-Saharan Africa. Our long-term goal is to elucidate the molecular mechanisms that are critical to rickettsial transmission by fleas in order to better understand the epidemiology of flea-borne rickettsial diseases and identify points of intervention. In addition to being a horizontally transmitted flea-borne pathogen, R. felis is alsoa vertically maintained endosymbiont of non-hematophagous insects. For arthropod-borne Rickettsia spp., the level of virulence is expected to be governed by the relative importance of vertical and horizontal transmission for maintenance of the rickettsiae. Therefore, the central hypothesis being tested is that there are host-dependent mechanisms that are essential to rickettsial virulence and transmission. The mechanism by which R. felis differentiates the host environment and executes either horizontal or vertical routes for successful transmission and maintenance in arthropod populations are not known. The experimental focus of this proposal is to delineate the Rickettsia- and arthropod-dependent factors contributing to successful horizontal transmission through comparative and functional analyses of R. felis in different arthropod hosts, and at the arthropod-host interface. The biological and molecular events underlying the transmission of R. felis in flea hosts are poorly defined and are critical to clearl understanding the epidemiology of flea-borne rickettsial diseases and identify points of intervention. The previously undefined parameters of rickettsial infection in fleas will be determined in the following specific aims Aim 1. Characterization of rickettsial transcript expression profile in cat fleas compared to non- hematophagous arthropods. Using RNA-seq, expressed rickettsial transcripts will be identified in R. felis- infected fleas, during flea hematophagy, and in rickettsiae deposited into blood during horizontal transmission between cofeeding fleas. Comparisons will be made to constitutively infected booklice. Subsequently, unique rickettsial transcripts will be functionally characterized via targeted gene disruption and their requirement for horizontal transmission assessed. Utilizing in vivo systems, we will be able to test the hypothesis that R. felis has an essential transcript profile necessary for horizontal transmission during flea bloodmeal acquisition. Aim 2. Determination of cat flea-derived salivary gland secreted factors essential for horizontal transmission of Rickettsia. The salivary gland transcription profile has been initially characterized in cat fleas and salivary gland transcripts identified as secreted molecules will be assessed in R. felis-infected cat fleas during the feeding period. Differentially expressed transcripts associated with R. felis infection of fleas will be functionally characterized by RNA-mediated interference and the necessity of these flea- derived factors for horizontal transmission assessed. Utilizing a horizontal transmission bioassay, the hypothesis that flea-derived factors are essential to successful horizontal transmission of R. felis will be tested.

描述(申请人提供)：1991年，费立克次体最初在美国被确认为一种人类病原体；随着全世界越来越多的认识，现在人们认识到，在撒哈拉以南非洲的非疟疾疾病中，由费氏立克次体引起的人类感染占发烧原因的6%。我们的长期目标是阐明通过蚤类传播立克次体的关键分子机制，以便更好地了解蚤传播立克次体疾病的流行病学并确定干预点。除了是一种水平传播的跳蚤传播的病原体外，它也是一种垂直维持的非食血性昆虫的内共生体。对于节肢动物传播的立克次体，毒力水平预计将取决于垂直和水平传播对维持立克次体的相对重要性。因此，正在测试的中心假设是，存在对立克次体毒力和传播至关重要的寄主依赖机制。在节肢动物种群中，如何区分寄主环境并执行水平或垂直路线以成功传播和维持的机制尚不清楚。这项建议的实验重点是通过对不同节肢动物寄主和节肢动物-宿主界面上的费氏立克次体的比较和功能分析，来描述有助于成功水平传播的立克次体和节肢动物依赖的因素。在跳蚤宿主中传播轮状芽胞杆菌的生物学和分子事件尚不清楚，对于明确了解蚤传播的立克次体疾病的流行病学和确定干预点至关重要。先前未确定的蚤类立克次体感染参数将在以下特定目标中确定：1.与非食血节肢动物相比，猫蚤中立克次体转录本表达谱的特征。利用RNA-SEQ技术，可以在感染菲律宾立克次体的蚤类中鉴定出表达的立克次体转录本，在吸食跳蚤的血噬过程中，也可以在共食蚤之间水平传播时沉积到血液中的立克次体中鉴定出表达的立克次体转录本。我们将把它与受结构性感染的书虱进行比较。随后，独特的立克次体转录本将通过有针对性的基因破坏进行功能表征，并评估它们对水平传播的需求。利用体内系统，我们将能够检验这一假设，即在跳蚤血粉获取过程中，费氏乳杆菌具有水平传播所必需的必要转录谱。目的2.检测猫蚤唾液腺分泌的水平传播立克次体致病因子。已初步确定猫蚤的唾液腺转录图谱，并将在猫蚤的取食过程中评估被鉴定为分泌分子的唾液腺转录产物。 句号。通过RNA介导的干扰和评估这些蚤源因子水平传播的必要性，将通过RNA介导的干扰来鉴定与跳蚤感染相关的差异表达转录本。利用水平传播生物测定，将检验跳蚤来源的因子对成功的水平传播是必不可少的假设。