Typhoid Pathogenesis and Immunity

伤寒发病机制和免疫

• 批准号: 8883985
• 负责人: Ferric C Fang
• 金额: $ 25.51万
• 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/8883985
• 关键词: Acute; Anabolism; Animal Model; Antigens; Apoptosis; Attenuated; Bacterial Genes; Biological Assay; Blood Cells; 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; Gram-Negative Bacteria; Hematopoietic stem cells; Human; Immune Sera; Immune response; Immunity; Infection; Intervention; Iron; Laboratories; Libraries; Life; 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; Signal Pathway; System; T-Cell Proliferation; T-Lymphocyte Subsets; Testing; Thymus Gland; Tissues; Transcriptional Regulation; Typhoid Fever; Typhoid Vaccine; Umbilical Cord Blood; Vaccinated; Vaccination; Vaccines; Vi capsular polysaccharide; Virulence; Virulent; adaptive immunity; caspase-3; chemokine; cytokine; 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（由适用提供）：人类病原体沙门氏菌（STY）每年引起超过2000万感染和200,000人死亡。我们的实验室开发了一种新型伤寒模型，该模型使用了植入脐带血的人类造血干细胞的人源性小鼠。这是第一个概括的小动物模型 急性造型感染的特征病理和致死性。我们还获得了证据表明，通过促进替代激活途径，造型在人类巨噬细胞中的持续存在，并表明可以用活的衰减造型疫苗菌株对人性化小鼠进行免疫，从而引起受保护的适应性免疫反应。该应用基于我们的初步观察，以检验中心假设，即沙门氏菌Typhi通过促进替代性巨噬细胞激活而逃避了人类的先天免疫，并需要适应性免疫学才能清除。该应用程序的具体目的是：1。确定允许造型在人类巨噬细胞中持续存在的机制。我们发现，造型在培养的人类巨噬细胞中持续存在，而STM会导致快速的细胞死亡。这是理解伤寒和非细域沙门氏菌感染的发病机理差异的重要线索。细胞表面标记，信号通路以及与巨噬细胞极化和凋亡相关的细胞因子/趋化因子将在人类巨噬细胞中分配，以了解沙门氏菌与人类巨噬细胞的沙门氏菌相互作用方面的血清特异性差异。 2。分析人源化小鼠中病毒所需的造型遗传位置。高复杂性转座子突变库鉴定了人源化小鼠造型增殖所需的细菌基因。屏幕已经确定了已知的和新颖的毒力确定剂，包括参与VI囊囊多糖产生和出口的基因，转录调控，中央代谢，O-抗原修饰和IV型Pilus生物合成。深入分析将确定反沉降转录调节剂的作用，新型的渗透酶复合物，铁摄取系统和IV型pili在伤寒发病机理中的作用。 3.将受保护的适应性免疫呼吸剂表征为人源性小鼠的造型疫苗。我们已经表明，人性化的小鼠在用活衰减的疫苗进行疫苗后会产生受保护的反应。详细的免疫特征将分析适应性免疫回报对人源化小鼠的疫苗，并确定疫苗吸收保护的机理。相关性：这些研究将提高我们对伤寒发病机理的理解，并建立一个新的研究平台，以评估候选伤寒疫苗。