Host-pathogen interactions in experimental cholera

项目摘要 霍乱是由霍乱弧菌引起的一种严重的脱水性肠道疾病。这个革兰氏阴性杆菌 在小肠定植并引起爆发性流行病的不寻常能力。在这里，我们将解决 霍乱弧菌与宿主相互作用的基本问题，利用我们所使用的许多方法和工具， 在过去的几十年里，霍乱弧菌O 1，大流行性霍乱的原因，分为小川 和Inaba血清型，其区别仅在于末端O-抗原甲基化的存在或不存在 糖分别。在霍乱流行期间小川和稻叶血清型的转换一直是 世纪以来，血清型转换对病原体适应性的影响一直没有得到承认， 清楚我们发现Ogawa血清型比Inaba血清型具有更大的体内适应性， 这两种血清型依赖于不同的体内生长代谢过程。因此，有意想不到的直接或 O-抗原甲基化对体内霍乱弧菌生长的间接表型和生理学后果。 霍乱弧菌血清型体内适应性差异的后果和机制 将在目标1中确定。霍乱毒素（CT）触发肠液分泌，这在很大程度上占 胆汁性腹泻。我们发现，CT还导致数百种宿主蛋白质的分泌，这些蛋白质在 肠上皮细胞对霍乱弧菌的转录反应。许多这些 蛋白质和转录本与先天免疫反应有关，我们发现其中一种蛋白质， 表面活性剂蛋白D（SP-D）限制了肠道中的霍乱弧菌生长。在目标2中，我们将分析 研究SP-D介导的保护机制，并研究额外的霍乱弧菌诱导的 分泌的宿主蛋白质阻碍病原体的定植，以揭示宿主的先天性轴， 对抗霍乱弧菌感染霍乱流行病通常传播非常迅速， 增加霍乱弧菌的感染性，但霍乱弧菌和宿主基因控制霍乱传播， 大部分未知。在目标3中，我们将利用我们在病原体条形码方面的经验和一种新的计算方法， 目的1和2中开发的扩展分析框架，检查血清型和CT在 调节宿主引发的感染性。控制V的其他病原体途径和宿主过程。 此外，亦会阐释霍乱的传染性，以加深对霍乱传播的认识。统称 拟议的研究将产生新的理解的相互关联的过程，管理霍乱弧菌 肠道定植和感染性以及限制定植的宿主因素和机制， 控制传输。这项工作将为两种霍乱弧菌血清型的生物学提供新的视角， 以及霍乱毒素在刺激宿主对病原体的先天防御反应中的作用。我们 这些发现也将对设计新的霍乱治疗方法具有重要的转化意义， 疫苗。

Project Summary Cholera is a severe dehydrating diarrheal disease caused by Vibrio cholerae. This Gram-negative rod has the unusual capacity to colonize the small intestine and to cause explosive epidemics. Here we will address fundamental questions in V. cholerae-host interactions, leveraging many of the approaches and tools we have created in the past decades. V. cholerae O1, the cause of pandemic cholera, is divided into Ogawa and Inaba serotypes, which differ only by the presence or absence of methylation of the terminal O-antigen sugar respectively. Switching of the Ogawa and Inaba serotypes during cholera epidemics has been recognized for over a century, but the consequences of serotype conversion on pathogen fitness are not clear. We discovered that the Ogawa serotype has greater in vivo fitness than the Inaba serotype and that the two serotypes rely on distinct metabolic process for growth in vivo. Thus, there are unexpected direct or indirect phenotypic and physiological consequences of O-antigen methylation on V. cholerae growth in vivo. The consequences and mechanisms that underlie the in vivo fitness differences of the V. cholerae serotypes will be determined in Aim 1. Cholera toxin (CT) triggers the intestinal fluid secretion that largely accounts for choleric diarrhea. We found that CT also leads to the secretion of hundreds of host proteins identified in diarrheal fluid and re-models the intestinal epithelial transcriptional response to V. cholerae. Many of these proteins and transcripts are linked to innate immune responses and we found that one of these proteins, surfactant protein D (SP-D), restricts V. cholerae growth in the intestine. In Aim 2, we will analyze the protective mechanisms mediated by SP-D and investigate the roles of additional V. cholerae-induced secreted host proteins in impeding the pathogen’s colonization, to uncover host innate axes that protect against V. cholerae infection. Cholera epidemics often spread extremely rapidly, and host passaging increases V. cholerae infectivity, but the V. cholerae and host genes that govern cholera transmission are largely unknown. In Aim 3, we will leverage our experience with pathogen barcoding and a new computational framework to extend analyses developed in Aims 1 and 2, examining the roles of serotype and CT in modulating host-priming of infectivity. Additional pathogen pathways and host processes that control V. cholerae infectivity will also be elucidated, to deepen understanding of cholera transmission. Collectively, the proposed research will yield new understanding of the interconnected processes that govern V. cholerae intestinal colonization and infectivity as well as the host factors and mechanisms that limit colonization and control transmission. This work will provide new perspectives on the biology of the two V. cholerae serotypes, and on the actions of cholera toxin in stimulating innate host defense responses against the pathogen. Our findings will also have important translational implications for design of new cholera therapeutics and vaccines.