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（由申请人提供）：1991年，在美国将立克菲利斯（Rickettsia Felis）定为人类病原体；而且，随着全球认可的越来越多，现在已经意识到，由R. felis引起的人类感染占撒哈拉以南非洲非疟疾状况中发烧原因的6％。我们的长期目标是阐明对跳蚤的立克传播至关重要的分子机制，以便更好地了解跳蚤式立克疾病的流行病学并识别干预点。除了是水平传播的跳蚤病原体外，R。felis还垂直维持非肿瘤昆虫的内共生菌。对于节肢动物传播的立克属属，预计毒力的水平将受垂直和水平传播对维持立克的相对重要性的影响。因此，正在检验的中心假设是，存在宿主依赖的机制，这些机制对于立克毒力和传播至关重要。 R. Felis区分主机环境并执行水平或垂直路线以成功传播和维护节肢动物种群的机制。该提案的实验重点是描述利克西亚和节肢动物依赖性因素，从而通过在不同节肢动物宿主中的比较和felis进行了比较和功能分析，以及在节肢动物 - 霍斯特 - 宿主界面上的比较和功能分析。 Felis在跳蚤宿主中传播的生物学和分子事件的定义很差，对于清除跳蚤式立克疾病的流行病学至关重要，并确定了干预点。在以下特定目的目标中，将确定跳蚤中立克感染的先前不确定的参数。与非血管性节肢动物相比，CAT跳蚤中立克sialsial sarkistript表达谱的表征。使用RNA-seq，将在Felis感染的跳蚤，在跳蚤的血型中鉴定出表达的立克转录本，在跳蚤的血管中，在辅助跳蚤之间的水平传播期间沉积在血液中的立克西亚。比较将与组成型感染的布莱克斯进行比较。随后，通过靶向基因破坏及其对水平传播的要求，将在功能上表征独特的立克转录本。利用体内系统，我们将能够检验以下假设：R。Felis具有在跳蚤血液采集期间水平传播所必需的基本转录物概况。目标2。确定猫跳蚤衍生的唾液腺分泌因子对于立克的水平传播所必需的。唾液腺转录曲线最初是在猫跳蚤和唾液腺转录本中表征的 时期。与跳蚤的Felis感染相关的差异表达的转录本在功能上以RNA介导的干扰以及这些衍生因子的必要性来评估水平传播。利用水平传播生物测定，将测试跳蚤来源的因素对于成功的水平传播至关重要。