Long Polar Fimbriae of Attaching and Effacing Escherichia coli

附着和消除大肠杆菌的长极菌毛

• 批准号: 7846683
• 负责人: Alfredo G Torres
• 金额: $ 2.01万
• 依托单位: UNIVERSITY OF TEXAS MED BR GALVESTON
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-06-05 至 2010-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7846683
• 关键词: AT Rich Sequence; Adhesions; Animal Model; Bacterial Adhesins; Bacteriophages; Biological Products; Categories; Cells; Collaborations; Country; DNA; Data; Diagnostic; Diagnostic tests; Diarrhea; Disease; Enterocytes; Environment; Escherichia coli; Escherichia coli EHEC; Escherichia coli Infections; Escherichia coli O157; Evolution; Family; Fimbrial Adhesins; Food Safety; Funding; Gastrointestinal tract structure; Gene Cluster; Genes; Genetic; Goals; Hemolytic-Uremic Syndrome; Human; In Vitro; Infant; Infantile Diarrhea; Infection; Infectious Diseases Research; Interdisciplinary Study; International; Intestines; Investigation; Knowledge; Lesion; Letters; Link; Mediating; Mobile Genetic Elements; Modeling; Organism; Oryctolagus cuniculus; Outcome; Pathogenesis; Pathogenicity Island; Plasmids; Play; Prevalence Study; Process; Production; Promoter Regions; Property; Proteins; Regulation; Research; Research Personnel; Resources; Role; Staging; System; Testing; Therapeutic; Therapeutic Uses; Virulence; Virulence Factors; Virulent; Work; base; enteropathogenic Escherichia coli; fimbria; genetic regulatory protein; genome sequencing; human disease; improved; in vivo; innovation; insight; novel; novel therapeutics; pathogen; pathogenic Escherichia coli; pathogenic bacteria; prevent; prototype; public health relevance; research study; tissue tropism

DESCRIPTION (provided by applicant): The expression of Attaching and Effacing Escherichia coli (AEEC) virulence factors is a tightly regulated process, and, in some cases, the identification of these factors has been difficult because they are either repressed in vitro or the conditions of expression are unknown. While it is evident that expression of certain virulence factors is strictly associated with human disease, the additional factors present in AEEC strains that are linked to their pathogenic process remain unclear. Lack of a full understanding of how the genes encoding these additional virulence factors are controlled is important, because, without this knowledge, we are unlikely to understand the overall pathogenic properties of AEEC strains. Thus, our objective is to determine how the Long Polar (LP) fimbriae in AEEC strains contribute to pathogenesis and to use these fimbrial-encoding genes as markers to detect virulent strains. The central hypothesis is that, in addition to the already characterized colonization factors (e.g., intimin-mediated adhesion), AEEC strains possess a highly regulated LP fimbriae, that plays a role in the colonization process, and although the genes encoding these fimbriae are widely distributed in pathogenic E. coli strains, some LP fimbriae types are found exclusively in specific AEEC strains. We will test this hypothesis through three specific aims, which are to: 1) Define whether Ler and H-NS act as a selective silencing/anti-silencing defense system that controls LP fimbriae expression in AEEC strains; 2) Identify the regulatory protein(s) controlling LP fimbriae expression in atypical EPEC and determine in a rabbit model the function of LP fimbriae during colonization; and 3) Characterize the distribution of the LP fimbrial gene clusters among AEEC strains and determine whether certain LP fimbrial subunit types are reliable markers of different pathogenic AEEC strains. To accomplish our aims, we will fully characterize the functions of Ler, H-NS, and atypical enteropathogenic E. coli-encoded regulators under in vitro and in vivo (infant rabbit colonization model) conditions and perform a detailed study of prevalence of the lpf genes in specific subsets of pathogenic AEEC strains. Our research work is innovative because it capitalizes on our findings regarding novel colonization factors in AEEC strains and their potential application in therapeutics and diagnostics. The results from studies of the regulatory networks controlling LP fimbriae expression have significance, because we will be able to identify fundamental differences to explain the tissue tropism of different AEEC strains and to determine whether silencing of LP fimbriae is an example of a defense system that AEEC strains have against horizontally acquired genes. In addition, the use of the rabbit model will give us new insight into the pathogenesis and colonization properties of AEEC strains. An understanding of the mechanisms underlying AEEC colonization to the gastrointestinal tract will not only further our knowledge of the pathogenesis of these organisms but also provide opportunities for reducing infection rates and improving treatment options against these biological agents classified as category B pathogens due t their potential use as a food safety threat. PUBLIC HEALTH RELEVANCE: Attaching and effacing Escherichia coli (AEEC) represent a diverse group of isolates implicated in diarrhea in humans in several countries. Most AEEC strains possess highly regulated Long Polar (LP) fimbriae, which contribute to the intestinal colonization process of some of the AEEC isolates. Their full characterization will provide new and deeper insights into the process of AEEC colonization, and a better understanding of their regulatory mechanisms controlling expression, which will be a basis for developing novel therapeutics and simplified diagnostic tests

描述（由申请人提供）：附着和消除大肠杆菌 (AEEC) 毒力因子的表达是一个严格调控的过程，在某些情况下，这些因子的识别很困难，因为它们要么在体外受到抑制，要么在条件下受到抑制。的表达方式未知。虽然很明显某些毒力因子的表达与人类疾病密切相关，但 AEEC 菌株中存在的与其致病过程相关的其他因子仍不清楚。缺乏对编码这些额外毒力因子的基因如何受到控制的充分了解非常重要，因为如果没有这些知识，我们就不可能了解 AEEC 菌株的整体致病特性。因此，我们的目标是确定 AEEC 菌株中的长极性 (LP) 菌毛如何促进发病机制，并使用这些菌毛编码基因作为标记来检测强毒菌株。核心假设是，除了已经表征的定植因子（例如 intimin 介导的粘附）之外，AEEC 菌株还拥有高度调节的 LP 菌毛，该菌毛在定植过程中发挥作用，尽管编码这些菌毛的基因广泛存在分布于致病性大肠杆菌菌株中，一些 LP 菌毛类型仅在特定的 AEEC 菌株中发现。我们将通过三个具体目标来检验这一假设，即：1）定义Ler和H-NS是否作为选择性沉默/抗沉默防御系统来控制AEEC菌株中LP菌毛的表达； 2) 鉴定控制非典型 EPEC 中 LP 菌毛表达的调节蛋白，并在兔模型中确定 LP 菌毛定植期间的功能； 3) 表征 AEEC 菌株中 LP 菌毛基因簇的分布，并确定某些 LP 菌毛亚基类型是否是不同致病性 AEEC 菌株的可靠标记。为了实现我们的目标，我们将在体外和体内（婴儿兔定植模型）条件下充分表征 Ler、H-NS 和非典型肠病性大肠杆菌编码调节因子的功能，并对 lpf 的患病率进行详细研究致病性 AEEC 菌株特定亚群中的基因。我们的研究工作具有创新性，因为它利用了我们关于 AEEC 菌株中新型定植因子及其在治疗和诊断中的潜在应用的发现。控制 LP 菌毛表达的调控网络的研究结果具有重要意义，因为我们将能够识别根本差异，以解释不同 AEEC 菌株的组织向性，并确定 LP 菌毛沉默是否是 AEEC 防御系统的一个例子。菌株具有对抗水平获得的基因。此外，兔模型的使用将使我们对AEEC菌株的发病机制和定植特性有新的了解。了解 AEEC 在胃肠道定植的机制不仅将加深我们对这些生物体发病机制的了解，而且还为降低感染率和改进针对这些生物制剂的治疗方案提供了机会，这些生物制剂因其潜在用途而被归类为 B 类病原体作为食品安全威胁。公共卫生相关性：附着和消除大肠杆菌 (AEEC) 代表了多个国家中与人类腹泻有关的多种分离株。大多数 AEEC 菌株具有高度调控的长极 (LP) 菌毛，这有助于某些 AEEC 分离株的肠道定植过程。它们的完整表征将为 AEEC 定植过程提供新的、更深入的见解，并更好地理解它们控制表达的调节机制，这将成为开发新疗法和简化诊断测试的基础