Functional genomics analysis of colonization and persistence of Enterococcus faecalis in the gastrointestinal tract.

 描述（由申请人提供）：本项目将研究粪肠球菌核心基因组内编码的决定因素在适应哺乳动物胃肠道中的生存、生长和持久性中的作用。E.粪菌是医院获得性感染的主要原因，其治疗受到生物体固有和获得性抗生素耐药性、其在恶劣条件下生长和存活的倾向以及其在寄生虫和致病性生活方式之间转变的能力的阻碍。几乎所有的肠球菌感染都是由肠道内的微生物逃逸到其他身体部位引起的。众所周知，抗生素治疗或正常宿主防御的损害可导致肠球菌在肠道中过度生长。然而，我们对允许生物体在健康肠道中建立的固有特征知之甚少，这是肠球菌疾病的基本前奏。我们将在无菌小鼠和携带人源性肠道微生物群落的“人源化”动物中研究模型实验室菌株OG1RF。我们将使用我们称为“Smart TnSeq”的强大的新遗传筛选来识别编码蛋白质和小调控RNA的遗传决定因素，这些蛋白质和小调控RNA有助于胃肠道的竞争适应性，并开始研究它们的功能和作用机制。我们将使用高分辨率显微技术来检查生物体在体内的行为，以及感兴趣的基因的表达。这项研究的结果将包括以下几点：1）一个全基因组的肠道健康的决定因素的作用的图片将出现。2)我们将有一个更好的了解肠球菌的首选网站的殖民化，以及如何在这些有利的小生境基因表达的调控。3)从长远来看，我们可以确定新的基于生态的策略，可以预防肠球菌感染，而不一定杀死细菌，减少耐药性的选择。

 DESCRIPTION (provided by applicant): This project will examine the role of determinants encoded within the core genome of Enterococcus faecalis in adaptation to survival, growth, and persistence in the mammalian gastrointestinal tract. E. faecalis is a leading cause of hospital-acquired infections whose treatment is impeded by the inherent and acquired antibiotic resistance of the organism, and by its propensity to grow and survive in hostile conditions, and by its ability to transition between commensal and pathogenic lifestyles. Virtually all enterococcal infections are caused by organisms residing in the gut that escape to other body sites. It is well understood that antibiotic treatment or impairment of normal host defenses can result in overgrowth of enterococci in the intestine. However, we know very little about the inherent traits that allow the organism to establish in a healthy intestine, an essential prelude t enterococcal diseases. We will study the model laboratory strain OG1RF in both germ-free mice, and in "humanized" animals carrying a human-derived gut microbial community. We will use a powerful new genetic screen we have termed "Smart TnSeq" to identify genetic determinants encoding proteins and small regulatory RNAs that contribute to competitive fitness in the GI tract, and begin to study their functions and mechanisms of action. We will use high-resolution microscopic techniques to examine the behavior of the organisms in vivo, and the expression of genes of interest. The results of this research will include the following: 1) A genome-wide picture of the role of determinants of intestinal fitness will emerge. 2) We will have a much better understanding of preferred sites of colonization of enterococci, and how gene expression is regulated in these favored niches. 3) In the longer term, we may identify new ecologically based strategies, which could prevent enterococcal infections without necessarily killing the bacteria, reducing selection for resistance.