Study of transmissible forms of Vibrio cholerae

描述(申请人提供)：霍乱弧菌是一种兼性病原体，也是霍乱的病原体。该病的特征包括由分泌的霍乱毒素作用引起的大量水样腹泻，以及致命的爆炸性疫情。在有未经处理的饮用水的地区，流行病与人类过度拥挤之间的强烈联系表明，通过水生媒介进行粪便-口腔传播是一种有效的方式。为了支持这一观点，我们发现霍乱弧菌在离开霍乱患者时处于高度可传播性状态(称为高度传染性)，这种状态在排放到池塘水中后持续几个小时。了解这种表型的分子基础，以及对这种可传播形式的霍乱弧菌的一般特征，将有助于设计疫苗，以在感染的初始阶段预防霍乱。在以前的工作中，我们发现缺乏趋化性的运动性是高传染性的一个决定因素。为了确定其他有助于传播的决定因素，我们测量了人类排泄物中霍乱弧菌在向水生微型世界转变过程中的整体转录变化。这项分析揭示了一些可能导致霍乱传播的调节器和效应器。在相关工作中，我们使用基因选择来识别在感染后期“预诱导”的基因，这些基因随后在霍乱弧菌向水环境的转变中发挥作用。在该项目的目标1和2中，我们建议确定在感染后期或在霍乱粪便中调节的基因是否在池塘水的转变和高度传染性中发挥重要作用。在这些表型中具有重要作用的转录调控因子将通过转录图谱进一步分析，以定义它们相应的调控因子。在目标2中，我们还建议测量和关联霍乱粪便霍乱弧菌在向池塘水过渡过程中转录组和蛋白质组的变化。在目标3中，我们建议应用传播效应器的知识来开发和测试黏膜疫苗，并在小鼠母体免疫和幼鼠挑战模型中进行测试。我们推测，一种表达在可传播形式的霍乱弧菌表面稳定表达的抗原库的无细胞疫苗将增强对这种病原体的攻击的保护。这些研究将为了解霍乱弧菌的高度感染表型及其向水环境的过渡奠定基础。这一知识将加强我们对这种或其他水传播病原体传播的了解，有助于为开发针对可传播形式的兼性病原体的新型疫苗铺平道路。与公共卫生相关：许多折磨人类的疾病是由通过受污染的供水传播的微生物引起的。水生水库中病原体的生物学以及它们进化成帮助其传播的特征在很大程度上是未知的。我们的项目将使用霍乱的病原体作为模式病原体来揭示这些进化的特征，并将使用获得的知识来测试一种针对病原体的传播形式的新型疫苗。

DESCRIPTION (provided by applicant): Vibrio cholerae is a facultative pathogen and the causative agent of cholera. Hallmarks of the disease include profuse watery diarrhea resulting from the action of secreted cholera toxin, and deadly, explosive outbreaks. The strong link between epidemics and human overcrowding in areas with untreated drinking water suggests an efficient mode of fecal-oral transmission via an aquatic intermediate. In support of this notion, we discovered that V. cholerae exit cholera victims in a heightened state of transmissibility (referred to as "hyperinfectivity"), which persists for several hours after shedding into pond water. Knowledge of the molecular basis for this phenotype, and a general characterization of this transmissible form of V. cholerae, would contribute to the design of vaccines to prevent cholera at the initial stage of infection. In prior work, we discovered that motility in the absence of chemotaxis is one determinant of hyperinfectivity. To identify additional determinants aiding in transmission, we measured global transcriptional changes in human-shed V. cholerae during the transition to an aquatic microcosm. This analysis revealed a number of regulators and effectors that potentially contribute to cholera transmission. In related work, we used a genetic selection to identify genes that are `pre-induced' at late stages of infection and which subsequently play roles in the transition of V. cholerae to aquatic environments. In Aims 1 and 2 of this project, we propose to determine if genes regulated late in infection or in cholera stool play important roles in the transition to pond water and in hyperinfectivity. Transcriptional regulators with important roles in these phenotypes will be further analyzed by transcriptional profiling to define their corresponding regulons. In Aim 2, we also propose to measure and correlate changes in the transcriptome and proteome of cholera stool V. cholerae during the transition to pond water. In Aim 3, we propose to apply knowledge of the effectors of transmission to develop and test a mucosal vaccine in a mouse maternal model of immunization and challenge of pups. We hypothesize that an acellular vaccine expressing a repertoire of antigens that are stably expressed on the surface of transmissible forms of V. cholerae will provide enhanced protection to challenge by the transmissible form of this pathogen. These studies will establish a basis for understanding both the hyperinfective phenotype of V. cholerae and its transition to aquatic environments. This knowledge will enhance our understanding of transmission of this and perhaps other water-borne pathogens, helping pave the way to development of novel vaccines that target transmissible forms of facultative pathogens. PUBLIC HEALTH RELEVANCE: Many of the diseases that afflict humans are caused by microbes transmitted via contaminated water supplies. The biology of pathogens in aquatic reservoirs and the traits they have evolved to aid in their transmission are largely unknown. Our project will use the causative agent of cholera as a model pathogen to uncover such evolved traits, and will use the knowledge gained to test a novel vaccine that targets the transmissible form of the pathogen.