权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Evasion of complement-mediated killing by pathogenic rickettsial species

致病性立克次体物种逃避补体介导的杀伤

基本信息

批准号：
8430190
负责人：
Juan J Martinez
金额：
$ 22.2万
依托单位：
LOUISIANA STATE UNIV A&M COL BATON ROUGE
依托单位国家：
美国
项目类别：
财政年份：
2013
资助国家：
美国
起止时间：
2013-02-15 至 2015-01-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8430190
关键词：
Actins Address Adhesions Alternative Complement Pathway Antibiotic Therapy Antibodies Antigens Arthropod Vectors Arthropods Bacteremia Bacteria Bacterial Adhesins Binding Binding Proteins Bioinformatics Bioterrorism Bite Blood Blood Circulation Blood Vessels Boutonneuse Fever Brain Categories Cells Centers for Disease Control and Prevention (U.S.)Complement Complement Factor H Complex Deposition Development Disease Disease Progression Endothelial Cells Endothelium Equilibrium Escherichia coli Family Fever Future Gene Family Genes Genome Goals Gram-Negative Bacteria Hematogenous Homologous Gene Human Human Factor H Immune system In Vitro Incubated Infection Infection Control Interstitial Pneumonia Invaded Investigation Liquid substance Lung Mammalian Cell Mammals Mediating Membrane Modeling Molecular Molecular Analysis Morbidity - disease rate Mus Mutagenesis National Institute of Allergy and Infectious Disease Open Reading Frames Organ Organism Pathogenesis Phase Plasma Proteins Proteobacteria Pulmonary Edema Research Resistance Rickettsia Rickettsia Infections Rickettsia conorii Rickettsia rickettsii Rocky Mountain Spotted Fever Role Serum Serum Proteins Skin Spottings Surface Antigens System Ticks Tissues Typhus Virulence Yersinia bacterial resistance bactericide base cell motility defined contribution disorder prevention human disease human tissue in vivo in vivo Model interest killings member mortality mutant neutralizing antibody novel pathogen programs public health relevance research study resistance factors tool transmission process

项目摘要

DESCRIPTION (provided by applicant): The Gram-negative ¿-proteobacteria of the genus Rickettsia are small (0.3-0.5 x 0.8-1.0 ?m), obligate intracellular organisms. They are categorized into two major groups, the Spotted Fever Group (SFG) and Typhus Group (TG), which can be distinguished by antigenicity and intracellular actin-based motility. Members of this genus are responsible for severe human diseases and several species including R. conorii and R. rickettsii, have been classified as Category B and C Priority Pathogens by the National Institute of Allergy and Infectious Diseases (NIAID) and as the Select Agents (R. rickettsii) by the Centers for Disease Control and Prevention (CDC) for their potential use as tools for biological terrorism. We have recently determined that in the absence of neutralizing antibodies, a model SFG rickettsial species, R. conorii the etiologic agent of Mediterranean spotted fever (MSF), is able to evade complement-mediated killing in human and murine serum. These results suggested that R. conorii and possibly other rickettsial species likely have evolved active mechanisms to evade the bactericidal effects of complement deposition as the pathogen disseminates in the bloodstream to target organs and tissues. We have identified two highly conserved rickettsial antigens, rOmpB/Sca5 and RC1281/Adr1, which are sufficient to mediate survival in ex-vivo human serum models of rickettsia bacteremia. We have demonstrated that R. conorii interact with human Factor H (fH), a fluid phase regulator of the alternative complement pathway and that rOmpB co-immunopreciptates with human fH, demonstrating its ability to serve as a bona fide fH binding protein (fHbp). We have also demonstrated that R. conorii survival is compromised when incubated in human serum depleted of fH suggesting that specific rickettsial interactions with serum components are critical to survival. Homologues to rOmpB and RC1281 exist in all pathogenic rickettsiae suggesting that the ability to actively perturb complement-mediated killing in the blood is a novel virulence attribute for this class of pathogens. The experiments outlined in this proposal will address the following research interests: i. The contribution of rickettsial fH binding proteins to serum resistance will be analyzed in vitr using surrogate expression systems in E. coli. We will initially determine the significance of rOmpB and RC1281 to serum resistance in vitro and will also determine the mechanisms underlying the evasion of complement-mediated killing. ii. The contribution of generated targeted insertion mutants in rompB/sca5 and rc1281 will be analyzed using in vitro and in vivo models of R. conorii and R. rickettsii infection.

描述（由申请人提供）：立克次体属的革兰氏阴性变形菌较小（0.3-0.5 x 0.8-1.0？m），专性细胞内生物。它们被分为两个主要的组，斑点热组（SFG）和斑疹伤寒组（TG），这可以通过抗原性和细胞内肌动蛋白为基础的运动来区分。该属的成员负责严重的人类疾病和几个物种，包括R。conorii和R.立克次氏体已被美国国家过敏和传染病研究所（NIAID）分类为B类和C类优先病原体，并被分类为选择性病原体（R.立克次氏体），因为它们可能被用作生物恐怖主义的工具。我们最近确定，在缺乏中和抗体的情况下，SFG立克次体的模式种，R。地中海斑点热（MSF）的病原体康氏酵母能够逃避人和鼠血清中补体介导的杀伤。这些结果表明，R.当病原体在血流中传播到靶器官和组织时，康氏立克次体和可能的其它立克次体物种可能已经进化出主动机制来逃避补体沉积的杀菌作用。我们已经确定了两个高度保守的立克次体抗原，rOmpB/Sca 5和RC 1281/Adr 1，这是足以介导的生存在离体立克次体菌血症的人血清模型。我们证明了R. conorii与人因子H（fH）相互作用，所述人因子H是旁路补体途径的液相调节剂，并且rOmpB与人fH共免疫沉淀，证明了其作为真正的fH结合蛋白（fHbp）的能力。我们还证明了R.当在缺乏fH的人血清中孵育时，康氏立克次体的存活受到损害，这表明立克次体与血清组分的特异性相互作用对存活至关重要。rOmpB和RC 1281的同源物存在于所有致病性立克次氏体中，这表明在血液中主动干扰补体介导的杀伤的能力是这类病原体的新毒力属性。本提案中概述的实验将涉及以下研究领域： I.将在E.杆菌我们将首先确定rOmpB和RC 1281对体外血清抗性的意义，并确定逃避补体介导的杀伤的机制。二.将使用R的体外和体内模型分析rompB/sca 5和rc 1281中产生的靶向插入突变体的贡献。conorii和R.立克次体感染