NOVEL E. COLI 0157:H7 INTESTINAL COLONIZATION FACTORS

说明(改编自应用程序) 典型的大肠杆菌O157：H7感染的基本第一阶段是定植 在肠道中。到目前为止，只有一种细菌因素被证明可以 外膜蛋白内膜蛋白O157：H7介导肠粘连 最初是在首席调查员的实验室里发现的。 然而，各种观察表明，额外的肠道 定植因素可能在大肠杆菌O157：H7和 总体目标是产生志贺毒素的O157：H7以外的血清型大肠杆菌 本项目的主要目的是研究大肠杆菌O157：H7和 非O157：H7出血性肠出血性大肠杆菌定植于肠道。我们的方法将 专注于四个具体目标。其中三个具体目标将集中在 新近发现的三种潜在定殖因子的特征 EHEC。这些因素中有两个与先前描述的粘附素在 其他肠道致病菌与第三因子没有明显的同源性 先前描述的粘附素。对于这些因素中的每一个，我们将构建 结构基因的同源非极性突变并检测突变体 新鲜分化的肠上皮细胞系的粘附性降低 采集人类肠道上皮细胞，并在灵知生菌仔猪模型中 疾病的威胁。被证明参与了三部小说中的任何一部 肠道粘连因素将为疫苗提供新的靶点 发展。第四个目标将集中在一种新的监管机制上 最具特征性的肠出血性肠出血性大肠杆菌的定植因子--内膜蛋白。我们最近展示了 粘附素和III型分泌系统的体外表达 编码在Lee致病岛上的基因受自身诱导物正向调节 正常菌群大肠杆菌菌株表达的分子，即群体感应。我们 建议通过构建一个测试群体感应在体内是否活跃的 O157：H7衍生产品不再对法定人数感应和测试做出响应 在猪模型中的殖民。如果群体感应在体内是活跃的，这将 基于抑制的潜在治疗干预开辟新领域 群体感应机制，从而减少肠道组织的表达 殖民因素。

DESCRIPTION (adapted from the application) The essential first stage of typical E. coli O157:H7 infection is colonization of the intestinal tract. To date, only one bacterial factor has been shown to mediate intestinal adherence by O157:H7, the outer membrane protein intimin which was originally discovered in the Principal Investigator's laboratory. However, a variety of observations indicate that additional intestinal colonization factors may play a role in disease due to E. coli O157:H7 and Shiga toxin-producing E. coli of serotypes other than O157:H7 The overall goal of this project is to investigate the mechanisms by which E. coli O157:H7 and non-O157:H7 enterohemorrhagic E. coli colonize the intestine. Our approach will be focused in four specific aims. Three of the specific aims will focus on characterization of three newly discovered potential colonization factors of EHEC. Two of these factors have homology to previously described adhesins in other enteric pathogens and the third factor has no obvious homology to previously described adhesins. For each of these factors we will construct isogenic non-polar mutations in the structural gene and test the mutants for decreased adherence in differential intestinal epithelial cell lines, freshly harvested human intestinal epithelial cells, and in a gnotobiotic piglet model of disease. The demonstrated involvement of any of the three novel colonization factors in intestinal adherence would provide new targets for vaccine development. The fourth aim will focus on a novel regulatory mechanism of the best-characterized EHEC colonization factor, intimin. We recently showed that in vitro expression of the intimin adhesin and the type III secretion system encoded on the LEE pathogenicity island is positively regulated by autoinducer molecules expressed by normal flora E. coli strains, i.e., quorum sensing. We propose to test whether quorum sensing is active in vivo by constructing an O157:H7 derivative that no longer responds to quorum sensing and testing it for colonization in a pig model. If quorum sensing is active in vivo, this would open up a new area for potential therapeutic intervention based on inhibiting the quorum sensing mechanism, thereby decreasing expression of intestinal colonization factors.