Investigating virulence functions of mastitis-associated Extraintestinal pathogenic Escherichia coli relevant to human disease

研究与人类疾病相关的乳腺炎相关肠外致病性大肠杆菌的毒力功能

• 批准号: 10439133
• 负责人: David L. Erickson
• 金额: $ 37.88万
• 依托单位: BRIGHAM YOUNG UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-01-13 至 2024-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10439133
• 关键词: Anabolism; Animal Model; Animals; Anti-Bacterial Agents; Antibiotic Resistance; Bacteria; Bar Codes; Case Fatality Rates; Cattle; Clinical; Collection; Complement; DNA; Dairy Products; Dangerousness; Data; Disease; Environment; Escherichia coli; Escherichia coli Infections; Food; Frequencies; Genes; Genetic; Goals; Health; Host Defense; Human; Infection; Intestines; Kidney; Knowledge; Lead; Life; Mammals; Measures; Meat; Methods; Molecular; Mus; Neonatal meningitis; Nutritional Immunity; Pathogenesis; Phagocytosis; Phenotype; Phylogenetic Analysis; Pneumonia; Population; Production; Public Health; Resistance; Resistance to infection; Risk Assessment; Role; Route; Sepsis; Septicemia; Serum; Skin; Soft Tissue Infections; Source; Spleen; Structure; Testing; Tissues; Urinary tract infection; Vaccination; Virulence; Virulence Factors; Virulent; Work; Zoonoses; base; capsule; cell killing; disorder prevention; experimental study; exposed human population; fitness; functional genomics; genome wide screen; gut colonization; human disease; human model; human pathogen; improved; innovation; mastitis; mouse model; mutant; neutrophil; new therapeutic target; novel; novel therapeutic intervention; pandemic disease; pathogen; pathogenic Escherichia coli; pathogenic bacteria; prevent; therapeutic target; transmission process; Anabolism; Animal Model; Animals; Anti-Bacterial Agents; Antibiotic Resistance; Bacteria; Bar Codes; Case Fatality Rates; Cattle; Clinical; Collection; Complement; DNA; Dairy Products; Dangerousness; Data; Disease; Environment; Escherichia coli; Escherichia coli Infections; Food; Frequencies; Genes; Genetic; Goals; Health; Host Defense; Human; Infection; Intestines; Kidney; Knowledge; Lead; Life; Mammals; Measures; Meat; Methods; Molecular; Mus; Neonatal meningitis; Nutritional Immunity; Pathogenesis; Phagocytosis; Phenotype; Phylogenetic Analysis; Pneumonia; Population; Production; Public Health; Resistance; Resistance to infection; Risk Assessment; Role; Route; Sepsis; Septicemia; Serum; Skin; Soft Tissue Infections; Source; Spleen; Structure; Testing; Tissues; Urinary tract infection; Vaccination; Virulence; Virulence Factors; Virulent; Work; Zoonoses; base; capsule; cell killing; disorder prevention; experimental study; exposed human population; fitness; functional genomics; genome wide screen; gut colonization; human disease; human model; human pathogen; improved; innovation; mastitis; mouse model; mutant; neutrophil; new therapeutic target; novel; novel therapeutic intervention; pandemic disease; pathogen; pathogenic Escherichia coli; pathogenic bacteria; prevent; therapeutic target; transmission process

Abstract/Project Summary Extraintestinal Escherichia coli (ExPEC) are bacteria that live in the intestines of mammals and cause life- threatening illnesses when they infect other tissues. The societal burden due to this group of pathogens is vast and growing, in part because of increasing antibiotic resistance and a lack of vaccination options. Urosepsis, pneumonia and neonatal meningitis are human diseases caused by these strains. Our long-term goal is to understand the molecular mechanisms of pathogenesis of ExPEC that circulate in animals and humans. Many animals are susceptible to these pathogens and represent reservoirs for human infection. The central hypothesis of this application, based on substantial preliminary data, is that some mastitis strains of bovine origin also have the potential to cause disease in multiple hosts including humans. This is a novel finding, based on evidence that includes genetic similarities with human ExPEC lineages, virulence in Galleria mellonella infections, resistance to human serum, and the ability to cause sepsis and urinary tract infections in mice. The objective of this work is to characterize virulence factors that allow some mastitis-associated strains to infect multiple hosts and cause extraintestinal disease. A genome-wide screen for mastitis strain M12 virulence factors led to the discovery of a cluster of capsule biosynthesis genes encoding a Group 3 capsule. Group 3 capsules are present in many ExPEC strains, but their roles are not well defined. An unencapsulated mutant strain was unable to infect spleens or kidneys of mice. Additional mastitis-associated strains in our collection also encode Group 3 capsules, which may promote virulence by helping these bacteria avoid neutrophil phagocytosis. Neutrophils are critically important for defense against many bacterial pathogens including ExPEC, but we do not fully comprehend the mechanisms whereby ExPEC resist being engulfed or killed by these cells. The objectives of this proposal will be accomplished with three specific aims: (1) Estimate the fraction of mastitis-associated E. coli that can cause disease in established models of human ExPEC infection. We will utilize novel DNA barcoding strategies to measure competitive fitness of multiple strains in these experiments. (2) Characterize the role of Group 3 capsules found in mastitis-associated strains in conditions relevant to human disease. We will test whether these capsules promote resistance to killing by neutrophils or serum and during experimental infections. (3) Identify all of the genes that are needed for production of the M12 Group 3 capsule, including those both inside and outside the capsule locus. Since building the capsule is a critical virulence function, this could identify targets for new therapies. This proposal is innovative because it is based on the novel concept that mastitis-associated strains are potential human pathogens. It is significant because it will provide greater understanding of the molecular basis for ExPEC virulence in multiple hosts, and the relationships between ExPEC found in different environments. These findings may inform new ways to prevent disease caused by these bacteria and improve public health.

摘要/项目摘要 肠外大肠杆菌（Expec）是生活在哺乳动物肠中并导致生命的细菌 - 当他们感染其他组织时，威胁疾病。由于这组病原体造成的社会负担很大 并成长，部分原因是抗生素耐药性增加和缺乏疫苗接种选择。尿素， 肺炎和新生儿脑膜炎是由这些菌株引起的人类疾病。我们的长期目标是 了解动物和人类循环的Expec发病机理的分子机制。许多 动物容易受到这些病原体的影响，代表了人类感染的储层。中央 基于大量初步数据的该应用的假设是牛的某些乳腺炎菌株 来源也有可能在包括人类在内的多个宿主中引起疾病​​。这是一个新颖的发现， 基于包括与人类专家谱系的遗传相似性的证据，在Galleria中的毒力 梅洛内拉感染，对人血清的抗性以及引起脓毒症和尿路感染的能力 老鼠。这项工作的目的是表征允许某些乳腺炎相关菌株的毒力因子 感染多个宿主并引起肠外疾病。乳腺炎菌株M12的全基因组筛查 毒力因子导致发现了编码3组胶囊的胶囊生物合成基因簇。 3组胶囊存在于许多Expec菌株中，但它们的作用并未得到很好的定义。一个未包容 突变株无法感染小鼠的脾或肾脏。我们的其他乳腺炎相关菌株 收集还编码3组胶囊，这可能通过帮助这些细菌来促进毒力 中性粒细胞增多症。中性粒细胞对于防御许多细菌病原体至关重要 包括expec，但我们不完全理解expec抗拒被吞噬或 被这些细胞杀死。该提案的目标将以三个特定的目的来实现：（1） 估计乳腺炎相关的大肠杆菌的分数，该大肠杆菌在既定的人类模型中可能引起疾病 Expec感染。我们将利用新颖的DNA条形码策略来衡量多重的竞争适应性 这些实验中的菌株。 （2）表征在乳腺炎相关菌株中发现的3组胶囊的作用 在与人类疾病有关的条件下。我们将测试这些胶囊是否促进了对杀戮的抵抗 中性粒细胞或血清以及实验感染。 （3）确定所有所需的基因 生产M12组3胶囊，包括胶囊基因座内部和外部的胶囊。自从 建立胶囊是一种关键的毒力功能，这可以识别新疗法的靶标。这个建议 具有创新性，因为它基于新颖的概念，即乳腺炎相关菌株是潜在的人类 病原体。这很重要，因为它将对Expec的分子基础有更深入的了解 多种宿主的毒力，以及在不同环境中发现的Expec之间的关系。这些 调查结果可能为预防这些细菌引起的疾病并改善公共卫生的新方法提供信息。