Type 1 fimbrial variation in E coil 018 k1 h7 virulence

描述(由申请人提供)：大肠杆菌菌株在成年妇女中产生阴道和尿路感染(UTI)和在新生儿中产生脑膜炎(NBM)的能力导致了对这些重要病原体的“粪便-阴道-尿路/新生儿”传播途径的研究。产生这些感染的大多数是有限数量的肠外致病性大肠杆菌(ExPEC)克隆，这些克隆的特点是拥有通过水平转移获得的多种毒力因子(VF)。虽然在所有ExPEC分离株中没有出现单一的典型VF，但几乎所有的大肠杆菌都表达1型菌毛，粘附性细丝被证明是肠道和肠外宿主生态位中必不可少的定植因素。菌毛的多功能性可能是连接共生和致病生活方式的桥梁，这是由于单核苷酸多态(SNPs)能够在1型菌毛粘附素(FimH)等位基因之间产生不同的功能特性。 O18：K1：H7血清型是ExPEC分离株中最流行的一组，在美国引起15%的大肠杆菌膀胱炎和20%的大肠杆菌NBM。在O18：K1：H7菌株中，SNPs确定了FimH的功能变异，具有独特的结合特性：包含A62的等位基因赋予剪切无关的结合，并与单链和胶原残基以及人膀胱上皮单分子层有较强的粘附性；S62等位基因赋予剪切依赖的结合，并且与这些底物的粘附力较弱。所有北美O18：K1：H7毒株都携带A62 FimH多态，以及(UTI相关VFS)P菌毛、溶血素和cnf1，而许多欧洲毒株携带S62 FimH，但没有这些VFS。 在特定的目标1和2中，我们将描述由018：KL：H7 FimH等位基因SNPs决定的独特特性，涉及宿主菌株的能力：(1)结合和入侵人类阴道和膀胱上皮，(2)被人中性粒细胞结合、摄取和杀死，以及(3)在小鼠模型中产生尿路感染。在具体目标3中，我们将分析大量的阴道大肠杆菌菌株以确定O18：K1：H7在阴道大肠杆菌O18：K1：H7中的流行率将评估VF携带性以及I型菌毛决定簇FimH和FimA的序列。除了识别正在进行的血清型进化，这些数据还将有助于开发一种基于SNPs的快速技术，用于在实验室分离株中识别O18：K1：H7菌株。这样的测试最终可能被用来识别绒毛膜羊膜炎和早产风险增加的妇女，或者分娩感染新生儿的风险增加的妇女。因此，所描述的工作可以减轻母亲和婴儿中的大肠杆菌疾病的负担。该提案还描述了候选人成为独立临床医生科学家的详细计划，特点是：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.