Type 1 fimbrial variation in E coil 018 k1 h7 virulence

描述（申请人提供）：E.大肠杆菌菌株在成年妇女中引起阴道和尿路感染（UTI）以及在新生儿中引起脑膜炎（NBM）的研究已经导致对这些重要病原体的“粪便-阴道-尿/新生儿”传播途径的研究。产生这些感染的大多数是数量有限的肠外致病性E。大肠杆菌（ExPEC）克隆，其特征在于具有通过水平转移获得的多种毒力因子（VF）。虽然没有单一的“经典”VF发生在所有的ExPEC分离株，几乎所有的E。大肠杆菌表达1型菌毛，粘附丝被证明是肠内和肠外宿主生态位中必需的定植因子。菌毛的多功能性，这可能是由于单核苷酸多态性（SNPs）的能力，产生1型菌毛粘附素，FimH的等位基因之间的变异功能特性的桥梁，致病性和致病性的生活方式。 O 18：K1：H7血清型构成了ExPEC分离株的最流行组，引起15%的E.大肠杆菌性膀胱炎占20%;大肠杆菌NBM在美国。在O 18：K1：H7菌株中，SNP确定了具有独特结合特性的FimH功能变体：含A62的等位基因赋予剪切非依赖性结合和对单甘露糖和胶原残基以及人膀胱上皮单层的强粘附; S62等位基因赋予剪切依赖性结合和对这些底物的弱粘附。所有北美O 18：K1：H7菌株携带A62 FimH多态性，以及（UTI相关VF）P菌毛、溶血素和cnf 1，而许多欧洲菌株携带S62 FimH，而不携带这些VF。 在特定目的1和2中，我们将表征由018：K1：H7 FimH等位基因SNP确定的独特性质，关于宿主菌株的以下能力：（1）结合和侵入人阴道和膀胱上皮，（2）被人嗜中性粒细胞结合、摄取和杀死，以及（3）在鼠模型中产生UTI。在具体目标3中，我们将分析大量收集的阴道E。大肠杆菌菌株，以确定O 18：K1：H7在阴道E.将评价大肠杆菌O 18：K1：H7分离株的VF携带情况以及I型菌毛决定簇fimH和fimA的序列。除了确定正在进行的血清型演变，这些数据还将有助于开发一种基于SNP的快速技术，用于在实验室分离株中鉴定O 18：K1：H7菌株。这样的测试最终可能被用来识别妇女在增加风险的绒毛膜炎和早产，或提供感染的新生儿。因此，所描述的工作可能导致E.母亲和婴儿的大肠杆菌病。该提案还描述了候选人成为独立临床科学家的职业发展的详细计划，包括：细菌发病机制和基因组学的教学课程，职业咨询委员会的定期评估，以及负责任的研究行为的培训。

DESCRIPTION (provided by applicant): The ability of E. coli strains to produce vaginal and urinary tract infections (UTIs) in adult women and meningitis in newborns (NBM) has led to study of the "fecal-vaginal-urinary/neonatal" route of transmission of these important pathogens. Producing most of these infections is a limited number of extraintestinal pathogenic E. coli (ExPEC) clones, which are characterized by possession of multiple virulence factors (VFs) that have been acquired by horizontal transfer. While no single "classic" VF occurs in all ExPEC isolates, virtually all E. coli express type 1 fimbriae, adhesive filaments shown to be essential colonization factors in both intestinal and extraintestinal host niches. The versatility of the fimbriae, which may bridge commensal and pathogenic lifestyles, is due to the ability of single nucleotide polymorphisms (SNPs) to produce variant functional properties among alleles of the type 1 fimbrial adhesin, FimH. The O18:K1:H7 serotype constitutes the most prevalent group of ExPEC isolates, causing 15% of E. coli cystitis and 20% of E. coli NBM in the United States. Among O18:K1 :H7 strains, SNPs have determined functional variants of FimH with distinctive binding properties: A62-containing alleles confer shear-independent binding and strong adhesion to monomannose and collagen residues, as well as human bladder epithelial monolayers; S62 alleles confer shear dependent binding, and weak adhesion to these substrates. All North American O18:K1 :H7 strains carry the A62 FimH polymorphism, as well as (UTI- associated VFs) P fimbriae, hemolysin and cnf1, while many European strains carry S62 FimH and none of these VFs. In Specific Aims 1 and 2, we will characterize distinctive properties determined by 018:Kl:H7 FimH allele SNPs, with regard to host strains' ability to: (1) bind and invade human vaginal and bladder epithelium, (2) be bound, ingested, and killed by human neutrophils, and (3) produce UTI in a murine model. In Specific Aim 3, we will analyze a large collection of vaginal E. coli strains to determine prevalence of O18:K1 :H7 among vaginal E. coli O18:K1:H7 isolates will be evaluated with regard to VF carriage as well as sequence of type I fimbrial determinants fimH and fimA. In addition to identifying ongoing serotype evolution, the data will also assist in development of a rapid technique - based on SNPs -for identifying O18:K1 :H7 strains among laboratory isolates. Such a test might ultimately be used to identify women at increased risk of chorioamnionitis and pre-term labor, or of delivering infected newborns. Thus, the work described could lead to reduction in the burden of E. coli disease among mothers and infants. The proposal also describes a detailed plan for the career development of the candidate into an independent clinician scientist, featuring: didactic coursework in bacterial pathogenesis and genomics, regular evaluations by a career advisory committee, and training in the responsible conduct of research.