Colonization and Pathogenicity Determinants of C. jejuni

描述(申请人提供)：空肠弯曲杆菌是美国细菌性胃肠炎最常见的原因，也是NIAID生物防御研究议程中指定的B类食物和水传播病原体。空肠弯曲菌的病例数量每年都超过了大肠杆菌、志贺氏菌，在某些年份甚至超过了沙门氏菌。疾病控制中心估计，考虑到报告和未报告的病例，每年有多达200万人死于弯曲杆菌病。大量人类病例是通过食用受污染和烹调不当的鸡肉获得的。人类感染会导致下肠道发炎，最终累及结肠和直肠。尽管生物体作为人类病原体很重要，但相对于其他病原体，人们对其毒力机制知之甚少。弯曲杆菌定植决定因素是在签名标记的突变筛选中确定的，使用的是雏鸡感染模型。在这项筛选中发现的基因中，有一些是N-连接蛋白糖基化系统所必需的，称为PGL基因。蛋白质糖基化在空肠弯曲菌生物学和致病相关行为中的作用尚未确定，但对空肠弯曲菌N-连接糖基的系统遗传分析揭示了这些基因中的一个子集，这些基因是在鸡模型中定植所需的。目的1研究这三种蛋白在空肠弯曲菌体内和体外致病模型中的作用，以及蛋白质糖基化对它们的特异性影响。目的2将通过两个特定的子目标对鸡模型进行进一步的研究：第一个目的是分析经口腔胃接种后和整个胃肠道中的突变的、低定植的细菌的命运；第二个是检验这样一个假设，即不具有野生型效果的突变细菌诱导独特的先天免疫反应，从而导致它们的低定植表型。Aim 3将开发和应用筛选小分子文库的方法，以筛选那些抑制空肠弯曲菌致病的关键特征的小分子，包括蛋白质糖基化和鞭毛组装。 这个项目将揭示关于一种重要的人类病原体--空肠弯曲杆菌的新知识。实验旨在确定糖化蛋白在宿主细胞联合和两种定植动物模型中的作用，包括鸡，空肠弯曲菌的天然宿主和人类感染的主要来源。这项工作包括一个组成部分，将把这一应用中的基础科学知识转化为研究和控制空肠弯曲菌感染的新试剂的开发。

DESCRIPTION (provided by applicant): Campylobacter jejuni is the most prevalent cause of bacterial gastroenteritis in the United States, and is also designated a Category B food-and waterborne pathogen under the NIAID Biodefense Research Agenda. Case numbers for C. jejuni annually surpass those of Escherichia coli, Shigella and, in some years, even Salmonella species. The Centers for Disease Control have estimated that there are up to 2 million illnesses from campylobacteriosis each year, considering reported and unreported cases. A large number of human cases are acquired by eating contaminated and poorly prepared chicken. Infection of humans results in inflammation of the lower intestinal tract that ultimately involves the colon and rectum. Despite the importance of the organism as a human pathogen, its mechanisms of virulence are poorly understood relative to those of other pathogens. Campylobacter colonization determinants were identified in a signature-tagged mutagenesis screen using a chick infection model. Among the genes identified in this screen were those required for N-linked protein glycosylation system, called pgl genes. The role of protein glycosylation in the biology and pathogenicity-related behavior of C. jejuni is not defined, but systematic genetic analysis of the N-linked glycome of C. jejuni has revealed a subset of these genes that are required for colonization in a chick model. Aim 1 will investigate three of these proteins and determine their roles in both in vivo and in vitro models of C. jejuni pathogenicity as well as the specific effect of protein glycosylation on them. Aim 2 will investigate the chick model further with two specific sub-aims: the first is to analyze the fate of mutant, poorly colonizing bacteria after oro-gastric inoculation and throughout the gastrointestinal tract and the second is to test the hypothesis that mutant bacteria that do not colonize the chicken with wild type efficacy induce a unique innate immune response that contributes to their poor colonization phenotype. Aim 3 will develop and apply assays for screening a library of small molecules for those that inhibit key traits of C. jejuni pathogenicity including protein glycosylation and flagellar assembly. This project will uncover new knowledge about an important human pathogen, Campylobacter jejuni. Experiments are designed to define the role of glycosylated proteins in host-cell association and in two animal models of colonization, including chickens, a natural reservoir of C. jejuni and major source of human infection. The work includes a component that will translate the knowledge from the basic science in this application to development of new reagents for studying and controlling C. jejuni infections.