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（通过应用程序提供）：革兰氏阴性�-人力素属的蛋白细菌很小（0.3-0.5 x 0.8-1.0？m），强制性细胞内生物。它们分为两个主要组，分别是斑点发烧组（SFG）和Typhus组（TG），可以通过抗原性和基于细胞内肌动蛋白的运动来区分。该属的成员负责严重的人类疾病，包括R. conorii和R. rickettsii在内的几种物种已被美国国家过敏和感染性疾病研究所（NIAID）（NIAID）归类为B和C优先病原体，并将其用于疾病控制和预防用途的恐怖主义（R. rickettsii）（R. rickettsii）（R. rickettsii）。我们最近确定，在没有中和抗体的情况下，SFG立克物种，R。Conorii，地中海发现发烧的病因（MSF），能够逃避人类和鼠类血清中的完全介导的杀伤。这些结果表明，Conorii和其他可能的立克物种可能发展了活跃的机制，以逃避完成沉积的细菌作用，因为病原体在血液中传播到靶器官和组织。我们已经确定了两种高度组成的立克抗原，ROMPB/SCA5和RC1281/ADR1，它们足以在Rickettsia细菌的前体血清模型中内侧存活。我们已经证明，R。conorii与人类因子H（FH）相互作用，即替代完成途径的流体相调节剂人体因子H（FH），并且ROMPB共免疫将与人FH共免疫沉淀，证明了其作为真正的FIDE FHE FH结合蛋白（FHBP）的能力。我们还证明，当在人类血清中孵育FH中，康罗伊河河河河河波菌的存活率受到损害，这表明特定的风险群与血清成分对生存至关重要。在所有致病性风险中都存在ROMPB和RC1281的同源物，这表明在血液中积极扰动完成介导的杀害的能力是这类病原体的一种新型病毒属性。该提案中概述的实验将解决以下研究兴趣：我。人力体FH结合蛋白对血清抗性的贡献将在VITR中使用大肠杆菌中的替代表达系统进行分析。我们最初将确定ROMPB和RC1281对体外血清耐药性的重要性，还将确定补体介导的杀戮演变的基础机制。 ii。将使用R. conorii和R. rickettsii感染的体外和体内模型分析ROMPB/SCA5和RC1281中产生的靶向插入突变体的贡献。