GAS Switch from Colonizing Bacterium to Invasive Pathogen

GAS 从定植细菌转变为侵袭性病原体

• 批准号: 9232048
• 负责人: Victor Nizet
• 金额: $ 36.4万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2020-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9232048
• 关键词: Active Immunization; Adherence; Adopted; Alpha Cell; Animals; Antibodies; Antibody titer measurement; Antigens; Attention; Attenuated; Autophagocytosis; Bacteria; Biogenesis; Biological Assay; Blood Circulation; Carbohydrates; Cations; Cell Communication; Cell Wall; Complement; Conjugate Vaccines; Coupled; Developing Countries; Development; Disease; Disease model; Epithelial; Epithelial Cells; Epitopes; Funding; Genes; Genetic; Grant; Host Defense; Human; Immune; Immune Evasion; Immune Sera; Immunologics; In Vitro; Individual; Infection; Infectious Skin Diseases; Inflammatory; Inflammatory Response; Innate Immune System; Integration Host Factors; Investigation; Knockout Mice; Knowledge; Life; Lymphoid Tissue; Mediating; Microbial Biofilms; Modeling; Molecular; Molecular Genetics; Morbidity - disease rate; Mus; Natural Immunity; Necrotizing fasciitis; Nose; Outcome; Passive Immunization; Pathogenesis; Peptides; Phagocytes; Phagocytosis; Play; Prevention strategy; Proteins; Regimen; Regulation; Research; Resistance; Rheumatic Fever; Rheumatic Heart Disease; Role; Safety; Septicemia; Serotyping; Serum; Side; Skin; Source; Streptococcal Infections; Streptococcus pyogenes; Structure; System; Systemic infection; Time; Tissue Model; Toxic Shock Syndrome; Vaccination; Vaccine Antigen; Vaccines; Vertebral column; Virulence; Virulence Factors; Virulent; Vitronectin; Work; antimicrobial peptide; base; cross reactivity; human disease; human tissue; immune clearance; immune resistance; in vivo; in vivo Model; insight; killings; leukocyte activation; macrophage; mortality; mouse model; mutant; neutrophil; novel; novel therapeutics; pathogen; pressure; programs; public health relevance; response; success; tissue culture

 DESCRIPTION (provided by applicant): Group A Streptococcus (GAS) is a preeminent pathogen causing a wide spectrum of human diseases. The propensity of particular GAS strains to produce systemic infection defines its capacity to resist host innate immune clearance mechanisms. A clone of the GAS M1T1 serotype spread globally over the last 40 years as the leading cause of invasive infections. Our lab adopted a multifaceted approach to understanding GAS and host factors explaining diverse outcomes of this host-pathogen interaction, using invasive M1T1 GAS clone as a primary model. Our approach coupled precise, targeted of candidate virulence factor genes with in vitro, ex vivo and in vivo models of disease pathogenesis, including WT and knockout mouse lines. We hypothesized that the outcome of GAS infection is dictated by the action and regulation of these GAS virulence factors in response to selective pressures exerted by host innate immunity. In the first funding period, we examined more than two dozen individual virulence factors of the GAS M1T1 clone and their extra- and intracellular interaction with host neutrophils and macrophages, epithelial and endothelial barriers, and soluble immune effectors including antimicrobial peptides, complement proteins and antibodies. For this first renewal application, a key (originally unanticipated) discovery of the past year serves as the central focus for new investigation: our identification of the long-sought-after molecular genetic basis of the hallmark, species-defining, Lancefield group A cell wall carbohydrate antigen (GAC). Our genetic knowledge allowed us to generate the first, precise isogenic GAS M1T1 mutant lacking the Lancefield epitope, a GlcNAc side chain that extends from the polyrhamnose backbone of the antigen. Previously thought only to play a structural role in cell wall biogenesis, we demonstrated that the GlcNAc side-chain contributes to GAS disease pathogenesis by promoting GAS resistance to cationic defense peptides, serum and neutrophil killing, and a mutant lacking the GlcNAC side chain was markedly attenuated for virulence in vivo. The GlcNAc side-chain of GAC has been implicated in the immunopathogenesis of rheumatic heart disease, and we now have a genetic strategy for its elimination. Here we pursue a comprehensive analysis of the GAC GlcNAc side-chain in colonization and systemic virulence of GAS from different disease-associated serotypes, informed by the enhanced mechanistic understanding provided by studies of the original funding period. We will examine the role of the GAC GlcNAc side chain in GAS epithelial cell adherence and invasion, biofilm formation, intracellular survival, interaction with the autophagy system, resistance to macrophage killing, and modulation of leukocyte activation. In vivo, we will assess its role in GAS colonization, necrotizing skin infection and septicemia. Efficacy and safety of GlcNAc- deficient GAC as a universal vaccine antigen will be examined upon conjugation with three different proteins using an active immunization regimen in three different mouse models of GAS disease, with attention to antibody titers, promotion of opsono-phagocytosis and elimination of human tissue cross-reactivity.

 描述（由适用提供）：A组链球菌（气）是一种杰出的病原体，导致了广泛的人类疾病。特定气体菌株产生全身感染的承诺定义了其抵抗宿主先天免疫清除机制的能力。在过去40年中，气体M1T1血清型的克隆是侵入性感染的主要原因。我们的实验室采用了一种多方面的方法来理解气体和宿主因素，以使用侵入性M1T1气体克隆作为主要模型来解释这种宿主病原体相互作用的潜水员结果。我们的方法耦合了精确的，以候选病毒因子基因的靶向，其体外，体内和体内疾病发病机理的模型，包括WT和敲除小鼠系。我们假设气体感染的结果是由这些气体病毒因素的作用和调节决定的，以响应宿主先天免疫学施加的选择性压力。在第一个资金期间，我们检查了气体M1T1克隆的二十多个单个病毒因子及其与宿主中性粒细胞和巨噬细胞的细胞外和细胞内相互作用，上皮和内皮屏障，以及固体免疫效应，包括抗菌药物petides，补体蛋白质和抗体。对于第一次续订应用程序，过去一年的钥匙（最初是意外的）发现是新投资的核心重点：我们确定 标志性，物种定义的Lancefield A组A细胞壁碳水化合物抗原（GAC）的长期分子遗传基础。我们的遗传知识使我们能够生成缺乏兰斯菲尔德表位的第一个精确的同基因M1T1突变体，这是一种从抗原的polyrhamnose骨架延伸的GlcNAC侧链。以前认为仅在细胞壁生物发生中起着结构性作用，我们证明了GlcNAC侧链通过促进气体耐气性对阳离子防御肽，血清和中性粒细胞杀死的耐气性，并且缺乏GlcNAC链链的突变体对病毒In Vivo的病毒显着减轻。 GAC的GlcNAC侧链已隐含在风湿性心脏病的免疫发作中，我们现在有了其进化的遗传策略。在这里，我们对来自不同疾病相关的血清型的GAC GLCNAC侧链进行了全面分析，并通过对原始资金期间的研究提供了增强的机械理解，从而得出了来自不同疾病相关的血清型的气体病毒。我们将研究GAC GlcNAC侧链在气体上皮细胞粘附和侵袭，生物膜形成，细胞内存活，与自噬系统的相互作用，对巨噬细胞杀伤的耐药性以及白细胞活化的调节的作用。在体内，我们将评估其在气体定植，坏死性皮肤感染和败血病中的作用。在三种不同的小鼠气体疾病的小鼠模型中，将使用三种不同的蛋白质与三种不同的蛋白质进行结合，将其与三种不同的蛋白质进行结合时，将检查GLCNAC缺乏GAC作为通用疫苗抗原的功效和安全性，并注意抗体滴度，对抗体滴度，促进Opsono-Phagococococococococococipos来并促进人类组织交叉症的消除。