Typhoid Pathogenesis and Immunity

伤寒发病机制和免疫

• 批准号: 9208114
• 负责人: Ferric C Fang
• 金额: $ 47.23万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-06 至 2020-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9208114
• 关键词: Acute; Anabolism; Animal Model; Antigens; Apoptosis; Attenuated; Bacterial Genes; Biological Assay; Blood Cells; CASP3 gene; Calcium/calmodulin-dependent protein kinase; Cell Death; Cell Survival; Cell surface; Cells; Cessation of life; Characteristics; Clinical; Complex; Enzyme-Linked Immunosorbent Assay; Evaluation; Event; Fetal Liver; Gene Expression Regulation; Genes; Genetic; Genetic Determinism; Genetic Transcription; Gram-Negative Bacteria; Hematopoietic stem cells; Human; Immune Sera; Immune response; Immunity; Immunize; Immunologics; Infection; Intervention; Iron; Laboratories; Libraries; Macrophage Activation; Metabolism; Methods; Modeling; Modification; Monitor; Morbidity - disease rate; Mus; Natural Immunity; O Antigens; Operon; Organism; Pathogenesis; Pathology; Pathway interactions; Physiology; Pilum; Production; Research; Role; STAT1 gene; Salmonella; Salmonella infections; Salmonella typhi; Salmonella typhimurium; Serum Immunologic; Signal Pathway; System; T-Cell Proliferation; T-Lymphocyte Subsets; Testing; Thymic Tissue; Transcriptional Regulation; Typhoid Fever; Typhoid Vaccine; Umbilical Cord Blood; Vaccinated; Vaccination; Vaccines; Vi capsular polysaccharide; Virulence; Virulent; adaptive immune response; adaptive immunity; chemokine; cytokine; humanized mouse; improved; insight; macrophage; metal metabolism; mortality; mouse model; mutant; novel; pathogen; permease; prevent; public health relevance; response; uptake

 DESCRIPTION (provided by applicant): The human pathogen Salmonella Typhi (STy) causes more than 20 million infections and 200,000 deaths each year. Our laboratory has developed a novel model of typhoid fever that uses humanized mice engrafted with human hematopoietic stem cells obtained from umbilical cord blood. This is the first small animal model to recapitulate the characteristic pathology and lethality of acute STy infection. We have also obtained evidence to suggest that STy persists in human macrophages by promoting an alternative pathway of activation and shown that humanized mice can be immunized with a live attenuated STy vaccine strain to engender protective adaptive immune responses. This application builds upon our preliminary observations to test the central hypothesis that Salmonella Typhi evades human innate immunity by promoting alternative macrophage activation and requires adaptive immunity for clearance. The specific aims of the application are to: 1. Determine the mechanisms that allow STy to persist in human macrophages. We have found that STy persists in cultured human macrophages whereas STm causes rapid cell death. This is an important clue to understanding differences in the pathogenesis of typhoidal and non-typhoidal Salmonella infections. Cell surface markers, signaling pathways, and cytokines/chemokines associated with macrophage polarization and apoptosis will be assayed in human macrophages to understand serovar-specific differences in Salmonella interaction with human macrophages. 2. Analyze STy genetic loci required for virulence in humanized mice. A high-complexity transposon mutant library has identified bacterial genes required for STy proliferation in humanized mice. The screen has identified both known and novel virulence determinants including genes involved in Vi capsular polysaccharide production and export, transcriptional regulation, central metabolism, O-antigen modification, and type IV pilus biosynthesis. In-depth analysis will determine the roles of a counter-silencing transcriptional regulator, a novel permease complex, iron uptake systems and type IV pili in typhoid pathogenesis. 3. Characterize protective adaptive immune responses to STy vaccines in humanized mice. We have shown that humanized mice develop protective responses following vaccination with live attenuated STy. Detailed immunological characterization will analyze adaptive immune responses to vaccination of humanized mice and determine the mechanism of vaccine-elicited protection. Relevance: These studies will advance our understanding of typhoid pathogenesis and establish a new research platform for the evaluation of candidate typhoid vaccines.

 描述（由申请人提供）：人类病原体伤寒沙门氏菌 (STy) 每年导致超过 2000 万人感染和 20 万人死亡。我们的实验室开发了一种新型伤寒模型，该模型使用移植了从脐带血中获得的人类造血干细胞的人源化小鼠。这是第一个重现的小动物模型 急性 STy 感染的特征性病理学和致死率。我们还获得的证据表明，STy 通过促进另一种激活途径而持续存在于人类巨噬细胞中，并表明人源化小鼠可以用减毒活 STy 疫苗株进行免疫，以产生保护性适应性免疫反应。该应用建立在我们初步观察的基础上，以测试中心假设，即伤寒沙门氏菌通过促进替代性巨噬细胞激活来逃避人类先天免疫，并需要适应性免疫来清除。该应用的具体目标是： 1. 确定 STy 在人类巨噬细胞中持续存在的机制。我们发现 STy 持续存在于培养的人类巨噬细胞中，而 STm 会导致细胞快速死亡。这是了解伤寒和非伤寒沙门氏菌感染发病机制差异的重要线索。将在人类巨噬细胞中检测与巨噬细胞极化和细胞凋亡相关的细胞表面标志物、信号通路以及细胞因子/趋化因子，以了解沙门氏菌与人类巨噬细胞相互作用的血清型特异性差异。 2. 分析人源化小鼠毒力所需的 STy 遗传位点。高复杂性转座子突变体文库已鉴定出人源化小鼠 STy 增殖所需的细菌基因。该筛选已鉴定出已知和新的毒力决定因素，包括参与 Vi 荚膜多糖生产和输出、转录调控、中枢代谢、O 抗原修饰和 IV 型菌毛生物合成的基因。深入分析将确定反沉默转录调节因子、新型通透酶复合物、铁吸收系统和 IV 型菌毛在伤寒发病机制中的作用。 3. 表征人源化小鼠对 STy 疫苗的保护性适应性免疫反应。我们已经证明，人源化小鼠在接种减毒活 STy 疫苗后会产生保护性反应。详细的免疫学表征将分析人源化小鼠对疫苗接种的适应性免疫反应，并确定疫苗引起的保护机制。相关性：这些研究将增进我们对伤寒发病机制的理解，并为评估候选伤寒疫苗建立新的研究平台。