Shiga Toxin Production and Role in Pathogenesis

志贺毒素的产生及其在发病机制中的作用

• 批准号: 7262869
• 负责人: Alison A. Weiss
• 金额: $ 39.5万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-03-01 至 2012-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7262869
• 关键词: Address; Adenine; Affect; Amino Acids; Antibiotics; Bacteriophages; Binding; Blood Platelets; Cells; Cessation of life; Cleaved cell; Clinical; Coagulation Process; Colitis; Complication; Cultured Cells; Development; Diarrhea; Disease; Dose; Effector Cell; Endothelial Cells; Escherichia coli EHEC; Escherichia coli O157; Event; Family; Gene Expression; Genes; Hemolytic-Uremic Syndrome; Hybrids; Immune; In Vitro; Incidence; Infection; Inflammatory; Integration Host Factors; Intestines; Kidney; Lead; Life; Life Cycle Stages; Link; Lytic Phase; Mediator of activation protein; Modeling; Molecular; N glycosidase; Papio; Pathogenesis; Production; Protein Biosynthesis; RNA, Ribosomal, 28S; Recruitment Activity; Regulation; Research Personnel; Ribosomes; Role; Severity of illness; Shiga Toxin; Site; Thinking; Toxic effect; Toxin; United States; Variant; Viral; Virulence Factors; Virus; base; carbohydrate receptor; cytokine; globotriaosylceramide; in vivo; member; mouse model; mutant; neutrophil; pathogen; programs; receptor binding

DESCRIPTION (provided by applicant): E. coli O157:H7 is an emerging pathogen of major importance. Disease caused by E. coli O157:H7 is characterized by diarrhea, hemorrhagic colitis, and the potentially fatal complication, hemolytic uremic syndrome (HUS). Shiga toxin (Stx) is a major virulence factor of E. coli O157:H7. Two major antigenic variants of Shiga toxin, Stx1 and Stx2, share 55% amino acid homology, however Stx2 production has been associated with progression to severe disease, including HUS. We propose to examine two aspects of Shiga toxin in the pathogenesis of disease caused by E. coli O157:H7 - regulation of Shiga toxin production in the intestine and the molecular basis for the difference in potency between Stx1 and Stx2. The genes for Shiga toxin are encoded on bacterial viruses. Regulation of toxin production is strongly linked to factors that affect the virus life cycle, specifically factors that induce the viral lytic cycle, for example antibiotics such as ciprofloxicin. In Specific Aim 1 we will characterize factors that influence Stx2 expression in vitro and in vivo. In addition to amount of toxin production, the type of Shiga toxin produced during infection can influence the severity of disease, with Stx2 being by far the more potent toxin. While it is clear that Stx2 can induce cellular death, it is not clear that cellular death is required for development of HUS, and toxicity may occur at the organismal level. In Specific Aim 2 we will characterize hybrid Stx2/Stx1 mutants to determine why Stx2 is more potent than Stx1 using in vitro cell culture models. In Specific Aim 3 we will determine the potency of the hybrid mutants in vivo using a mouse model of disease. Understanding the viral, bacterial and host factors that influence Shiga toxin production and potency could lead to treatments that reduce the incidence of fatal disease.

描述（由申请人提供）：大肠杆菌 O157:H7 是一种重要的新兴病原体。由大肠杆菌 O157:H7 引起的疾病的特点是腹泻、出血性结肠炎和潜在致命的并发症溶血性尿毒症综合征 (HUS)。志贺毒素 (Stx) 是大肠杆菌 O157:H7 的主要毒力因子。志贺毒素的两个主要抗原变体 Stx1 和 Stx2 具有 55% 的氨基酸同源性，但 Stx2 的产生与严重疾病（包括 HUS）的进展有关。我们建议从两个方面研究志贺毒素在大肠杆菌 O157:H7 引起的疾病发病机制中的作用：肠道中志贺毒素产生的调节以及 Stx1 和 Stx2 效力差异的分子基础。志贺毒素的基因是由细菌病毒编码的。毒素产生的调节与影响病毒生命周期的因素密切相关，特别是诱导病毒裂解周期的因素，例如环丙沙星等抗生素。在具体目标 1 中，我们将描述影响 Stx2 体外和体内表达的因素。除了毒素产生量外，感染过程中产生的志贺毒素类型也会影响疾病的严重程度，其中 Stx2 是迄今为止更有效的毒素。虽然很明显 Stx2 可以诱导细胞死亡，但尚不清楚细胞死亡是否是 HUS 发生所必需的，并且毒性可能发生在有机体水平。在特定目标 2 中，我们将使用体外细胞培养模型来表征混合 Stx2/Stx1 突变体，以确定为什么 Stx2 比 Stx1 更有效。在具体目标 3 中，我们将使用小鼠疾病模型确定杂交突变体在体内的效力。了解影响志贺毒素产生和效力的病毒、细菌和宿主因素可能会导致减少致命疾病发生率的治疗方法。