MOLECULAR MECHANISMS OF YERSINIA PESTIS PERSISTENCE IN THE FLEA VECTOR

鼠疫耶尔森氏菌在跳蚤载体中持续存在的分子机制

• 批准号: 8415512
• 负责人: Viveka Vadyvaloo
• 金额: $ 18.88万
• 依托单位: WASHINGTON STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-02-01 至 2014-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8415512
• 关键词: Antibiotics; Antitoxins; Automobile Driving; Bacteria; Biological; Biological Assay; Bubonic Plague; Cell physiology; Cells; Development; Disease; Epidemic; Escherichia coli; Event; Exhibits; Exploratory/Developmental Grant; Fleas; Goals; Growth; Infection; Knowledge; Lead; Mediating; Metabolic; Microbial Biofilms; Molecular; Molecular Profiling; Nature; Operon; Phase; Phenotype; Physiological; Physiology; Plague; Population; Public Health; Research; Risk; Rodent; Role; Staging; Testing; Toxin; Translations; Up-Regulation; Variant; Yersinia pestis; antimicrobial; base; comparative; enzootic; epizootic; human disease; mutant; novel; prevent; transmission process; vector

DESCRIPTION (provided by applicant): Plague is a flea-borne zoonotic disease characterized by sylvatic cycles in wild rodent populations and their associated fleas. These sylvatic cycles are composed of an epizootic phase, which increases the risk of transmission and human disease, and an enzootic/quiescent stage in which the causative bacterium, Yersinia pestis, persists and maintains the reservoir. While epizootics can be supported by a biofilm-mediated gut blockage transmission mechanism, the basis of the enzootic/quiescent stage is unknown. We propose that this quiescence is mediated by a 'dormant' form of the bacterium which sustains persistence within the flea but can then revert to a transmissible infection upon favorable conditions. Understanding the molecular underpinnings of Y. pestis persistence during inter-epizootic periods would resolve a significant gap in knowledge and may lead to identification of new targets to prevent flea-borne transmission and epizootics. Our recent comparative transcriptional profiling of a Yersinia pestis ?phoP mutant versus a wildtype strain supports the presence of an alternate dormant survival state in the ?phoP mutant within the flea gut. Among other supporting phenomena descriptive of dormancy, numerous toxin:antitoxin (TA) modules that are responsible for dormant persister cell formation by downregulating essential cellular processes have exclusively elevated expression in the ?phoP mutant. This lead to the hypothesis that Y. pestis transitions into the self-protective survival state of dormancy which allows it to persist in the flea host, and that this phenotype is reversible and driven by TA module expression. The goal of the R21 exploratory research is to determine whether dormancy is a function of persistence and whether expression of TA modules are responsible for driving dormancy and reactivation of the biological biofilm gut blockage transmissible infection in Y. pestis. Experimentally this will be achieved by establishing whether dormancy is phenotypically and mechanistically a function of persistence by assessing the prolonged survivability and high tolerance to antibiotics, respectively of the dormant Y. pestis ?phoP mutant in the flea gut. Next, by creating a conditionally inducible phoP strain we will test whether dormant cells can be reactivated to cause a transmissible infection. Finally we will specifically test the role of TA modules in driving the dormant and reactivated gut blocked transmitting phenotypes of Y. pestis by creating conditionally inducible toxin expressing strains and assaying them for long term survival, antibiotic tolerance and biofilm gut blockage. This research is consistent with the exploratory/developmental nature of the R21 mechanism (as described in PA-10-069) because it explores uncharacterized molecular mechanisms that drive persistence of Y. pestis in the flea vector, which may lead to identification of new targets to prevent flea-borne transmission and epizootics.

描述（由申请方提供）：鼠疫是一种蚤传播的人畜共患疾病，其特征为野生啮齿动物种群及其相关蚤的森林化周期。这些森林循环由动物流行阶段和动物流行/静止阶段组成，动物流行阶段增加传播和人类疾病的风险，而在动物流行/静止阶段，致病细菌鼠疫耶尔森氏菌持续存在并维持宿主。虽然动物流行病可以通过生物膜介导的肠道阻断传播机制来支持，但动物流行/静止期的基础尚不清楚。我们认为这种静止是由一种“休眠”形式的细菌介导的，这种细菌在跳蚤体内持续存在，但在有利的条件下可以恢复为可传播的感染。了解Y的分子基础。鼠疫在动物流行病间隔期的持续存在将解决知识方面的重大空白，并可能导致确定预防跳蚤传播和动物流行病的新目标。我们最近的鼠疫耶尔森氏菌比较转录谱？phoP突变体与野生型菌株支持存在一个替代休眠生存状态？跳蚤肠道内的phoP突变体。在描述休眠的其他支持现象中，许多毒素：抗毒素（TA）模块通过下调基本细胞过程来负责休眠持续细胞形成，但在？phoP突变体。这导致了Y.鼠疫菌转变为休眠的自我保护生存状态，使其能够在跳蚤宿主中持续存在，并且这种表型是可逆的，并由TA模块表达驱动。R21探索性研究的目标是确定休眠是否是持续性的函数，以及TA模块的表达是否负责驱动休眠和Y中生物生物膜肠道阻断传染性感染的重新激活。鼠疫在实验上，这将通过分别评估休眠Y的延长的存活能力和对抗生素的高耐受性来确定休眠在表型上和机理上是否是持久性的函数来实现。鼠疫？跳蚤肠道中的phoP突变体。接下来，通过创建条件诱导型phoP菌株，我们将测试休眠细胞是否可以被重新激活以引起传染性感染。最后，我们将专门测试TA模块在驱动休眠和重新激活的肠道阻断Y的传播表型中的作用。通过创建条件诱导毒素表达菌株并测定它们的长期存活、抗生素耐受性和生物膜肠道堵塞来检测鼠疫。这项研究与R21机制的探索/发展性质一致（如PA-10-069中所述），因为它探索了驱动Y持久性的未表征分子机制。这可能导致确定新的目标，以防止跳蚤传播和动物流行病。