Pathogenicity of Shiga Toxin-Producing E. coli

产志贺毒素大肠杆菌的致病性

• 批准号: 6679345
• 负责人: Alison Davis O'Brien
• 金额: $ 19.14万
• 依托单位: HENRY M. JACKSON FDN FOR THE ADV MIL/MED
• 依托单位国家: 美国
• 财政年份: 1983
• 资助国家: 美国
• 起止时间: 1983-08-01 至 2008-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6679345
• 关键词: Enterobacteriaceae; Escherichia coli 0157:H7; Escherichia coli infections; Rodentias; Shigella dysenteriae; adhesin; antigen antibody reaction; bacillary dysentery; bacteria infection mechanism; bacterial cytopathogenic effect; bacterial genetics; cell adhesion; clinical research; hemolytic anemia; host organism interaction; human tissue; laboratory mouse; molecular pathology; protein structure function; receptor binding; renal failure; shiga toxin; swine; toxin metabolism; vaccine development; virulence

DESCRIPTION (provided by applicant): Enterohemorrhagic Escherichia coli (EHEC) O157:H7 belongs to a subset of Shiga toxin-producing E coli (STEC) that makes Shiga toxin (Stx) type 1 or type 2 (or a variant thereof), or both toxins, harbors pO157 (or a related plasmid) and expresses the adhesin intimin. Intimin is the product of the eae gene that is contained within a -43 kb pathogenicity island called the locus of enterocyte effacement or LEE. EHEC O157:H7 is the most common cause of bloody diarrhea (also called hemorrhagic colitis or HC) in the U.S. with an estimated incidence of 73,480 cases per annum. Moreover, the hemolytic uremic syndrome (HUS), a sequela of O 157:H7 infection, is the most frequent basis for acute kidney failure in U.S. children. The incidence of non-O157:H7 disease in this country is about half that of O157:H7, or 36,740 cases per year. Worldwide, the single most common serotype of STEC associated with human illness is O157:H7 but other serotypes have also been linked to development of HC and the HUS. The majority of such non-O157 isolates from humans are intimin positive, but intimin-negative strains of STEC have also been incriminated as causes of serious human disease. Because of the potential severity of STEC infection and because O157:H7 has a very low infectious dose 50% and can be spread from person to person, the bacterium is considered a category B biological threat by CDC. The long-term goals of this project are to define at the molecular, cellular, and whole animal levels the pathogenic mechanisms by which STEC cause disease and to develop strategies for prevention and treatment of STEC-mediated HC and HUS. The specific aims are to: 1. assess the cell biology and distribution of the elastase-activatable, highly potent, phage-encoded Stx2d toxin; 2. define the structure function relationship between intimin-gamma of E. coli O157:H7 and the eukaryotic receptor nucleolin and determine whether nucleolin also engages other types of intimin; 3. test the theory that the interaction between intimin-y and nucleolin on the host cell surface activates an intracellular response that is essential for EHEC O157:I-'17 adherence; 4. explore the hypotheses that O157:H7 strain 86-24 can induce intestinal A/E lesions in orally-infected mice if the strain is altered to express Citrobacter rodentium intimin alone or in concert with other C. rodentium LEE-encoded proteins and that such a strain more efficiently delivers Stx2 systemically than does wild-type and is, therefore, more virulent, and; 5. continue to evaluate as vaccine candidates the C-terminal fragments of intimin-gamma from EHEC O 157:H7 and intimin-alpha from enteropathogenic E. coli (EPEC) as well as Stxl and Stx2 toxoids for capacity to elicit antibodies that inhibit adherence of EHEC O157:H7 and EPEC to tissue culture cells and to neutralize Stxl and Stx2, respectively, and to assess the protective efficacy of these immunogens alone or in combination when given to animals either parenterally or orally in transgenic plant cells.

描述（由申请人提供）：肠出血性大肠杆菌 (EHEC) O157:H7 属于产志贺毒素大肠杆菌 (STEC) 的一个子集，可产生志贺毒素 (Stx) 1 型或 2 型（或其变体），或这两种毒素都含有 pO157（或相关质粒）并表达粘附素 intimin。 Intimin 是 eae 基因的产物，该基因包含在一个 -43 kb 致病岛内，称为肠细胞消失位点或 LEE。 EHEC O157:H7 是美国血性腹泻（也称为出血性结肠炎或 HC）的最常见原因，估计每年发病率为 73,480 例。此外，溶血性尿毒症综合征 (HUS)（O 157:H7 感染的后遗症）是美国儿童急性肾衰竭的最常见原因。该国非 O157:H7 疾病的发病率约为 O157:H7 疾病的一半，即每年 36,740 例。在世界范围内，与人类疾病相关的最常见的 STEC 血清型是 O157:H7，但其他血清型也与 HC 和 HUS 的发展有关。大多数此类从人类中分离出来的非 O157 菌株均为 intimin 阳性，但 Intimin 阴性 STEC 菌株也被认为是导致严重人类疾病的原因。由于 STEC 感染的潜在严重性以及 O157:H7 的感染剂量非常低（50%）并且可以在人与人之间传播，因此该细菌被 CDC 视为 B 类生物威胁。该项目的长期目标是在分子、细胞和整个动物水平上明确 STEC 引起疾病的致病机制，并制定预防和治疗 STEC 介导的 HC 和 HUS 的策略。具体目标是： 1. 评估弹性蛋白酶可激活、高效、噬菌体编码的 Stx2d 毒素的细胞生物学和分布； 2. 明确大肠杆菌O157:H7的intimin-gamma与真核受体核仁素之间的结构功能关系，并确定核仁素是否也与其他类型的intimin结合； 3. 测试宿主细胞表面的 intimin-y 和核仁素之间的相互作用激活细胞内反应的理论，该反应对于 EHEC O157:I-'17 粘附至关重要； 4. 探索以下假设：如果 O157:H7 菌株 86-24 被改变以单独表达 Citrobacter rodentium intimin 或与其他 C. rodentium LEE 编码蛋白协同表达，则该菌株可以诱导口腔感染小鼠的肠道 A/E 病变，并且这种菌株比野生型更有效地全身传递 Stx2，因此毒性更强； 5. 继续评估作为候选疫苗的 EHEC O 157:H7 的 intimin-gamma 和肠病性大肠杆菌 (EPEC) 的 intimin-alpha 的 C 末端片段以及 Stxl 和 Stx2 类毒素引发抑制粘附的抗体的能力将EHEC O157:H7和EPEC分别加入组织培养细胞并中和Stxl和Stx2，并评估保护功效当在转基因植物细胞中肠胃外或口服给予动物时，这些免疫原单独或组合使用。