Interaction between Vibrio cholerae and Dictylostelium discoideum

描述（由申请人提供）：弧菌种类主要是水生细菌。虽然其中许多是非致病性的，但有些弧菌与人类的严重疾病有关。特别是霍乱弧菌，具有引起流行病和大流行性霍乱的悠久历史。霍乱是由霍乱弧菌在小肠定植引起的，霍乱弧菌在小肠定植产生一种强效毒素，导致大量水分流失和电解质失衡。在自然界中，霍乱弧菌可能是自由生活的，但它的生存似乎是与其他生物体的特定联系所促进的。霍乱弧菌形成这些关联并在其水生生态系统中持续存在所需的一些基因也与促进人类疾病有关。体外研究表明，原生动物可能将霍乱弧菌作为食物来源，并促进霍乱弧菌的存活，但这些相互作用的性质尚不清楚。我们的研究将集中在霍乱弧菌和模式原生动物阿米巴盘基骨虫之间的关系，我们的实验室将这两种生物的专业知识结合起来。我们的假设是霍乱弧菌受到环境中变形虫的捕食，霍乱毒素等毒力因子的产生有助于保护霍乱弧菌免受捕食并提高其存活率。此外，我们提出碟状棘球蚴可以作为霍乱弧菌与变形虫相互作用的模型。我们将使用遗传，生化和细胞生物学的方法来解剖盘状弓形虫和霍乱弧菌之间的关系。突变体分析和基因筛选将用于鉴定在盘状弧菌存在下存活和持续所需的霍乱弧菌基因，我们将使用细胞生物学技术开始阐明盘状弧菌和霍乱弧菌之间的相互作用。具体目的是：(i)鉴定参与抵抗阿米巴虫捕食的霍乱弧菌基因，（ii）确定霍乱弧菌在盘状棘球蚴内的生存机制，以及（iii）确定在阿米巴虫存在下生长的霍乱弧菌是传染性的还是强毒性的。了解这种捕食者/猎物关系不仅可以提供有关环境中霍乱弧菌的基本信息，还可以为更好地控制霍乱弧菌的环境来源提供线索，从而有助于预防霍乱的流行。公共卫生相关性：霍乱弧菌是全世界发病率和死亡率的主要原因。这种细菌在自然界中有一个储存库，并周期性地重新出现，引起流行病和霍乱大流行。为了在野外生存，霍乱弧菌必须能够抵抗变形虫的捕食。拟议的研究确定抵抗捕食的机制将有助于更好地了解霍乱弧菌的生态学。这可能有助于制定控制霍乱弧菌传染源的战略。

DESCRIPTION (provided by applicant): Vibrio species are predominantly aquatic bacteria. While many of them are non-pathogenic, some vibrios are associated with severe disease in humans. Vibrio cholerae, in particular, has a long history of causing epidemic and pandemic cholera. Cholera results from colonization of the small intestine by V. cholerae, where it produces a potent toxin that results in massive water loss and electrolyte imbalance. In nature, V. cholerae may be found free-living, but its survival appears to be favored by specific associations with other organisms. Some of the genes required for V. cholerae to form these associations and persist in its aquatic ecosystem are also involved in promoting disease in humans. In vitro studies have suggested that protozoans may both use V. cholerae as a food source and promote V. cholerae survival, but the nature of these interactions is not well understood. Our studies will focus on the relationship between V. cholerae and the model protozoan amoeba Dictyostelium discoideum, and our laboratories have combined expertise in these two organisms. Our hypothesis is that V. cholerae is subject to predation by amoebae in the environment and that production of virulence factors such as cholera toxin helps protect V. cholerae from predation and enhances its survival. Further, we propose that D. discoideum can be used as a model for interaction of V. cholerae with amoebae. We will use genetic, biochemical, and cellular biology approaches to dissect the relationship between D. discoideum and V. cholerae. Analysis of mutants and genetic screens will be used to identify the V. cholerae genes required for survival and persistence in the presence of D. discoideum, and we will use cellular biology techniques to begin to elucidate the interactions between D. discoideum and V. cholerae. The specific aims are to (i) identify V. cholerae genes involved in resistance to predation by amoebae, (ii) determine the mechanism of survival of V. cholerae within D. discoideum, and (iii) determine whether V. cholerae grown in the presence of the amoeba are infectious or hypervirulent. Understanding this predator/prey relationship will not only provide basic information about V. cholerae in the environment, but also may provide clues to methods for better controlling the environmental sources of V. cholerae and thereby help prevent epidemics of cholera. PUBLIC HEALTH RELEVANCE: Vibrio cholerae is a major cause of morbidity and mortality worldwide. This bacterium has a reservoir in nature and periodically re-emerges to cause epidemics and pandemics of cholera. In order to persist in the wild, V. cholerae must be able to resist predation by amoebae. The proposed studies to determine the mechanisms of resistance to predation will lead to a better understanding of the ecology of V. cholerae. This may allow the development of strategies to control the source of epidemic V. cholerae.