0157:H7 INTIMIN AND STX--PATHOGENESIS IN A MOUSE MODEL

说明(改编自应用程序) 自20世纪80年代初以来，肠出血性大肠杆菌(EHEC)一直是 被认为是腹泻和出血性结肠炎的原因。最严重的 EHEC感染的并发症是溶血性尿毒症综合征(HUS)， 主要是在儿童中。虽然现在已经认识到EHEC菌株属于 可引起HUS的多种血清型中，O157：H7是主要的EHEC血清型 在世界上许多地方，它一直是最常见的与 食源性暴发。EHEC O157：H7毒力决定因素包括志贺毒素 (STX)，一种染色体致病岛，称为肠细胞基因座 LE，编码粘附素内蛋白，并介导附着和 消除(AE)活性，以及溶血素(HlyA)，一种丝氨酸蛋白酶 (ESPP)，以及一种与梭状芽孢杆菌同源的质粒编码的粘附素 艰难梭菌毒素B(Efal)。我们开发了一种柠檬酸杆菌的小鼠模型 依赖Lee编码基因产物和AE的齿状结肠炎 殖民活动。在这个模型中，哺乳的小鼠发展出显著的 结肠粘膜损伤，与严重结肠炎和死亡有关。 另一方面，成年小鼠出现结肠上皮增生和一种 轻度结肠炎，典型的亚临床症状。我们最近发现， 增加轮状芽孢杆菌的接种量(10-9cfu，灌胃)会导致 成年小鼠出现明显的粘膜损伤和严重的结肠炎。我们现在建议 通过引入个体建立O157：H7急性乙型病毒性肠炎小鼠模型 从EHEC O157：H7到轮状芽胞杆菌的毒力决定簇及其使用 感染成年小鼠的菌株。具体地说，我们将1)描述 O157：H7在AE结肠炎小鼠模型中的作用，2)表征 STX在这个AE结肠炎小鼠模型中的作用，以及3)粘膜反应的特征 体外和体内对O157：H7内膜和STX的作用。总的来说，这项工作将 允许我们测试依赖AE的粘膜损伤和结肠炎的假设 影响肠道中的STX易位。它还应该导致 研究O157：H7致病机理和致病机制的小鼠模型的建立 测试针对这一重要问题的预防和治疗方法 食源性疾病。

DESCRIPTION (adapted from the application) Since the early 1980s, enterohemorrhagic Escherichia coli (EHEC) has been recognized as a cause of diarrhea and hemorrhagic colitis. The most serious complication of EHEC infection is hemolytic uremic syndrome (HUS), which occurs primarily in children. While it is now recognized that EHEC strains belonging to a variety of serotypes can cause HUS, O157:H7 is the dominant EHEC serotype in many parts of the world and has been the type most commonly associated with foodborne outbreaks. EHEC O157:H7 virulence determinants include shiga toxins (Stx), a chromosomal pathogenicity island called the locus for enterocyte effacement (LEE) that encodes the adhesin intimin and mediates attaching and effacing (AE) activity, as well as a hemolysin (HlyA), a serine protease (EspP), and an plasmid-encoded adhesin with homology to the Clostridium difficile toxin B (Efal). We have developed a mouse model of Citrobacter rodentium colitis that is dependent on LEE-encoded gene products and AE activity for colonization. In this model, suckling mice develop significant mucosal damage in the colon, which is associated with severe colitis and death. Adult mice, on the other hand, develop colonic epithelial hyperplastic and a milder colitis that is typically subclinical. We have recently discovered that an increased inoculum of C. rodentium (10-9 CFU, intragastric) leads to significant mucosal damage and severe colitis in adult mice. We now propose to develop a mouse model of AE colitis for O157:H7 by introducing individual virulence determinants from EHEC O157:H7 into C. rodentium and using these strains to infect adult mice. Specifically, we will 1) characterize the role of O157: H7 intimin in this mouse model of AE colitis, 2) characterize the role of Stx in this mouse model of AE colitis, and 3) characterize the mucosal response to O157:H7 intimin and to Stx in vitro and in vivo. Overall, this work will allow us to test the hypothesis that AE-dependent mucosal damage and colitis influence Stx translocation from the gut. It should also lead to the development of a mouse model for studies of O157:H7 pathogenesis and for testing preventive and therapeutic approaches directed against this important foodborne illness.