Colonization and Pathogenicity Determinants of C. jejuni

描述（由申请人提供）：空肠弯曲杆菌是美国细菌性肠胃炎最常见的原因，并且在NIAID生物防御研究议程下也被指定为B类食物和水传播病原体。空肠梭菌每年的病例数超过了大肠杆菌、志贺氏菌，在某些年份甚至超过了沙门氏菌。美国疾病控制中心（Centers for Disease Control）估计，考虑到报告和未报告的病例，每年有多达200万人因弯曲杆菌病而患病。大量人间病例是由于食用了受污染和处理不当的鸡肉而感染的。人类感染会导致下肠道发炎，最终波及结肠和直肠。尽管该生物作为人类病原体的重要性，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鉴定在签名标记诱变筛选使用鸡感染模型。在筛选中发现的基因中，有n -连锁蛋白糖基化系统所需的基因，称为pgl基因。蛋白质糖基化在空肠梭菌的生物学和致病性相关行为中的作用尚未明确，但对空肠梭菌n -连锁糖基的系统遗传分析已经揭示了这些基因的一个子集是在鸡模型中定植所必需的。目的1将研究其中的三种蛋白，并确定它们在体内和体外空肠梭菌致病性模型中的作用，以及蛋白质糖基化对它们的具体影响。目的2将进一步研究鸡模型，有两个特定的子目标：第一是分析突变体，在口腔胃接种后和整个胃肠道中定植不良的细菌的命运；第二是验证假设，即不能以野生型效力定植鸡的突变体细菌诱导独特的先天免疫反应，导致其定植不良表型。目标3将开发和应用筛选小分子文库的方法，以抑制空肠梭菌致病性的关键特征，包括蛋白质糖基化和鞭毛组装。

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.