Identifying genes essential for Legionella persistence and transmission

 描述（由申请人提供）：水传播的病原体对全世界的人类健康构成严重威胁，使水质成为疾病发生率和严重程度的基本决定因素。细菌在海洋环境中生存和增殖的一个关键因素是食草阿米巴的存在。这些生物以细菌为食，在限制细菌种群方面发挥着核心作用。然而，许多细菌物种已经发展出在变形虫中生存和复制的策略。这导致了人类病原体的出现，因为这些策略可以类似地被细菌用来引起人类疾病。变形虫在细菌病原体的流行病学中也起着重要作用，因为它们的相互作用增强了病原体引起感染的能力。尽管这些相互作用的重要性，很少有人知道的细菌的要求，在变形虫的生长。这严重限制了我们对这些病原体如何在环境和人造水源中持续存在以及导致疾病发生率和严重程度的因素的理解。 细菌病原体军团菌存在于三分之二以上的饮用水分配系统中。通过吸入受污染的水气溶胶暴露于这种病原体，可导致危及生命的肺炎。军团菌能够在饮用水中存活，因为它能够在变形虫体内复制，从而保护细菌免受水消毒程序的杀灭。令人困惑的是，军团菌能够在多种类型的变形虫中生长。这是其在水库中生存的关键决定因素，在水库中阿米巴种群高度多样化。本研究的目的是确定细菌在阿米巴原虫中生长的要求以及军团菌从环境水库传播到人类的机制。为此，高通量表型筛选和功能基因组学将用于：1）系统地鉴定军团菌在不同阿米巴宿主中复制所必需的基因，以确定在所有宿主中普遍使用的核心毒力策略和允许军团菌适应宿主之间变异的辅助策略; 2）确定多种环境和临床分离株中毒力基因的保守性和功能重要性，以评估其编码蛋白的效用 作为对付各种军团菌的目标这些研究将为开发更有效的策略提供基础，以消除水资源中的细菌，降低感染风险，并对军团菌的发病机制有独特的见解，这将有助于开发治疗疾病的新策略。

 DESCRIPTION (provided by applicant): Water-borne pathogens pose a serious threat to human health world-wide rendering water quality a fundamental determinant of the incidence and severity of disease. A critical factor in bacteria survival and proliferation in marine environments is the presence of grazing amoebae. These organisms feed on bacteria, playing a central role in restricting bacterial populations. However, many bacterial species have developed strategies to survive and replicate within amoebae. This has contributed to the emergence of human pathogens as these strategies can similarly be used by the bacterium to cause disease in humans. Amoebae also play an important role in the epidemiology of bacterial pathogens as their interaction enhances the pathogen's ability to cause an infection. Despite the importance of these interactions, little is known about the bacterial requirements for growth in amoebae. This severely limits our understanding of how these pathogens persist in environmental and man-made water sources and the factors that contribute to the incidence and severity of disease. The bacterial pathogen Legionella is present in over two thirds of potable water distribution systems. Exposure to this pathogen occurs through the inhalation of contaminated water aerosols which can result in life-threatening pneumonia. Legionella survives in potable water due to its ability to replicate within amoebae, which protects the bacterium from killing by water disinfection procedures. Confounding this problem, Legionella is able to grow in multiple types of amoebae. This is a key determinant of its survival in water reservoirs where amoebal populations are highly diverse. The goal of this research is to define bacterial requirements for growth in amoebae and the mechanisms responsible for the transmission of Legionella from environmental reservoirs to humans. To do this, high throughput phenotypic screening assays and functional genomics will be used to: 1) Systematically identify Legionella genes essential for replication in diverse amoebal hosts to define core virulence strategies commonly used in all hosts and auxiliary strategies that allow Legionella to adapt to variation between hosts; 2) Determine the conservation and functional importance of virulence genes across multiple environmental and clinical isolates to assess the utility of their encoded proteins as targets against a broad spectrum of Legionellae. These studies will provide a foundation for developing more effecting strategies for eliminating bacteria from water resources to reduce the risk of infection and unique insight into Legionella pathogenesis that will be instrumental in developing novel strategies for treating disease.