Genetic and Ecological Factors in Transmissibility and Epidemic Cycle of Cholera

描述（由申请人提供）：属于O 1和O 139血清群的产毒素霍乱弧菌引起霍乱，这是一种急性水传播性霍乱病，在孟加拉国等许多发展中国家引起季节性流行病。虽然霍乱的传播通常通过被病原体污染的水发生，但促进霍乱流行传播和支持孟加拉国季节性流行病之间病原体在水中生存的自然机制尚不清楚。我们将应用一种新的方法，我们开发的AST监测和研究的性质“条件可行的环境细胞（CVEC）”的致病性V.霍乱存在于孟加拉国的表面沃茨。由于CVEC可能来源于人类霍乱粪便中霍乱弧菌的生物膜样聚集体，因此我们提出了一个广泛的计划来了解霍乱粪便中霍乱弧菌的感染形式及其在水生环境中的生存。我们将从环境沃茨中分离CVEC，并在动物模型中对其代谢、形态、免疫化学以及先天感染性进行表征。因为我们已经表明噬菌体捕食显然结束霍乱流行，我们将确定霍乱弧菌的CVEC是否由于其可能的低代谢活性或物理特性而受到噬菌体捕食的保护。我们提出的分析将包括生物化学和遗传学研究，旨在了解粪便来源的弧菌，其环境生存的CVEC和复苏的CVEC致病性活生物体的增强的传播性。我们建议从霍乱粪便（CVEC-H），或从实验感染兔（CVEC-R）或在完全实验室条件下（CVEC-L）脱落的细胞中产生CVEC样霍乱弧菌细胞。为了了解各种细胞类型之间转换的遗传基础，我们将进行基于微阵列的基因组转录分析。将使用标准遗传学方法来鉴定参与CVEC-R和CVEC-L形成的基因。2623个确定的转座子插入突变体库的霍乱弧菌将有助于系统地鉴定涉及低钠盐胁迫的基因。这些研究加上环境监测数据，应能更好地了解霍乱的传染周期，从而激发新的有效干预措施，在发展中国家中断这一疾病的自然史。

DESCRIPTION (provided by applicant): Toxigenic Vibrio cholerae belonging to the O1 and O139 serogroups cause cholera, an acute, waterborne diarrheal disease that causes seasonal epidemics in many developing countries such as Bangladesh. Although transmission of cholera typically occurs through water contaminated with the pathogenic organisms, the natural mechanisms that facilitate the epidemic spread of cholera and support the survival of the pathogen in water between seasonal epidemics in Bangladesh are not clear. We will apply a new method we developed called AST to monitor and study the nature of "conditionally viable environmental cells (CVEC)" of pathogenic V. cholerae that exist in surface waters of Bangladesh. Because CVEC are likely derived from biofilm-like aggregates of V. cholerae shed in human cholera stools, we propose a broad program to understand the infectious form of V. cholerae in cholera stools, and their survival in the aquatic environment. We will isolate CVEC from environmental waters and characterize them metabolically, morphologically, immunochemically, and for their innate infectivity in animal models. Because we have shown phage predation apparently ends cholera epidemics, we will determine whether CVEC of V. cholerae are protected from phage predation due to their possible low metabolic activity or physical properties. Our proposed analysis will include biochemical and genetic studies designed to understand enhanced transmissibility of stool-derived vibrios, their environmental survival as CVEC and resuscitation of CVEC to pathogenic viable organisms. We propose to produce CVEC-like V. cholerae cells from cholera stools (CVEC-H), or from cells shed by experimentally infected rabbits (CVEC-R) or under fully laboratory conditions (CVEC-L). To understand the genetic basis for the transition between various cell types, we will conduct microarray-based, genomic transcriptional analysis. Standard genetic methods will be utilized to identify genes involved in formation of CVEC-R and CVEC-L. A library of 2623 defined transposon insertion mutants of V. cholerae will aid in the systematic identification of genes involved in low sodium osmo-stress. Together with data from environmental monitoring, these studies should provide a better understanding of the infectious cycle of cholera and thus inspire new effective interventions for interrupting the natural history of this disease in developing countries.