Intestinal colonization of Enterohemorrhagic E. coil

肠出血性大肠杆菌的肠道定植

• 批准号: 7022840
• 负责人: Matthew K WALDOR
• 金额: $ 25.54万
• 依托单位: TUFTS UNIVERSITY BOSTON
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-02-01 至 2007-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7022840
• 关键词: DNA; diarrhea; genes; genome; human; infection; model; mutant; serotyping; virulence

DESCRIPTION (provided by applicant): Enterohemorrhagic Escherichia coli (EHEC) are an emerging group of food- and water-borne pathogens that colonize the distal ileum and colon and produce potent cytoxins. EHEC infection causes illnesses ranging from mild diarrhea to the potentially fatal hemolytic uremic syndrome. These bacteria particularly serotype O157:H7, represent a significant threat to public health and are classified as NIAID Category B Priority pathogens. The O157:H7 genome contains -1.4 megabases of DNA that are not present in the genome of non-pathogenic E. coli K-12. This additional DNA is interspersed as 177 'O-islands' along the backbone of sequences that are shared with E. coli K-12. Our central hypothesis is that the O-islands encode the majority of the pathogenic properties of E. coli O157:H7. All the reported EHEC virulence factors are encoded in O-islands, and we recently identified an additional O-island encoded factor, AcfO, that promotes EHEC intestinal colonization. We have developed methodology to rapidly and comprehensively survey the contribution of uncharacterized O-islands to EHEC pathogenicity. Although the interaction of E. coli O157:H7 with mammalian cells in vitro has been extensively studied, relatively little is known about the EHEC factors that are required for intestinal colonization. This gap in our knowledge is primarily due to the lack of a readily available animal model of human EHEC infection. Our preliminary data demonstrates that infant rabbits are an excellent model host for study of the intestinal manifestations of E. coli O157:H7 infection. Infant rabbits develop diarrhea and colitis, and quantitative analysis of intestinal colonization can be performed. In this proposal, we will utilize infant rabbits to carry out a comprehensive, high throughput screen of EHEC mutants with single O-islands deleted. In Aim I, we will identify the EHEC O-island genes that promote intestinal colonization. Our approach for investigating the mechanisms of action of gene products identified here is illustrated by the experiments proposed in Aim II, where we will characterize the expression, regulation, function, transmission and distribution of acfO. These studies will yield valuable new information about the mechanisms of EHEC pathogenicity and identify colonization factors that may provide new targets for novel therapeutics and vaccines.

描述（由申请方提供）：肠出血性大肠杆菌（EHEC）是一组新兴的食源性和水源性病原体，定植于回肠末端和结肠，并产生强效细胞毒素。肠出血性大肠杆菌感染引起的疾病范围从轻度腹泻到潜在的致命性溶血性尿毒综合征。这些细菌，特别是血清型O 157：H7，对公众健康构成重大威胁，被列为NIAID B类优先病原体。O 157：H7基因组含有约1.4兆碱基的DNA，这些DNA不存在于非致病性大肠杆菌基因组中。coli K-12。这种额外的DNA作为177个“O-岛”沿着与E. coli K-12。我们的中心假设是O岛编码了大肠杆菌的大部分致病特性。coli O157：H7。所有报道的肠出血性大肠杆菌毒力因子编码的O-岛，我们最近确定了一个额外的O-岛编码因子，AcfO，促进肠出血性大肠杆菌肠道定植。我们已经开发出一种方法，快速，全面调查的贡献，未知的O-岛肠出血性大肠杆菌的致病性。虽然E.大肠杆菌O 157：H7与哺乳动物细胞在体外的定植研究已得到广泛的研究，但对肠出血性大肠杆菌肠道定植所需的因子知之甚少。我们知识上的这一差距主要是由于缺乏一个现成的人类肠出血性大肠杆菌感染的动物模型。初步结果表明，幼兔是研究大肠杆菌肠道表现的理想模型宿主。大肠杆菌O 157：H7感染。幼兔发生腹泻和结肠炎，可以进行肠定植的定量分析。在本研究中，我们将利用幼兔进行一个全面的，高通量的筛选EHEC突变体与单O-岛删除。在目的一，我们将确定肠出血性大肠杆菌O-岛基因，促进肠道定植。我们的方法来调查这里确定的基因产物的作用机制说明了在目标II，在那里我们将表征acfO的表达，调节，功能，传输和分布提出的实验。这些研究将产生关于EHEC致病机制的有价值的新信息，并确定可能为新疗法和疫苗提供新靶点的定植因子。