Typhoid Pathogenesis and Immunity

伤寒发病机制和免疫

基本信息

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
项目类别：
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

项目摘要

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 万例感染和 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。我们还获得了证据表明 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。该应用程序基于我们的初步观察，以测试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的中心假设。该应用程序的具体目的是： 1. 确定 STy 在人类巨噬细胞中持续存在的机制我们发现 STy 在培养的人类巨噬细胞中持续存在，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、信号传导途径以及细胞因子/趋化因子，以了解沙门氏菌的血清型特异性差异2. 分析人源化小鼠中毒力所需的 STy 基因位点一个高复杂性转座子突变体库已鉴定出人源化小鼠中 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，包括相关基因。在 Vi 荚膜多糖的产生和输出、转录调控、中枢代谢、O 抗原修饰和 IV 型菌毛生物合成中的深入分析将确定其作用。伤寒发病机制中的反沉默转录调节因子、新型通透酶复合物、铁摄取系统和 IV 型菌毛。 3. 表征人源化小鼠对 STy 疫苗的保护性适应性免疫反应。我们已经表明，人源化小鼠在接种活疫苗后会产生保护性反应。详细的免疫学特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的理解。发病机制并建立一个新的研究平台来评估候选伤寒疫苗。