The Roles of Conserved outer-membrane proteins in SFG rickettsia pathogenesis

保守外膜蛋白在 SFG 立克次体发病机制中的作用

• 批准号: 8228058
• 负责人: Juan J Martinez
• 金额: $ 37.17万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-03-02 至 2012-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8228058
• 关键词: Address; Adherence; Adhesions; Aerosols; Antibiotic Therapy; Arthropod Vectors; Bacteria; Bacterial Adhesins; Binding; Bioterrorism; Bite; Blood Vessels; Boutonneuse Fever; Brain; Cell Culture Techniques; Cell Line; Cells; Complex; Coupled; Development; Disease; Elements; Endothelial Cells; Endothelium; Escherichia coli; Family; Fever; Future; G22P1 gene; Gene Family; Generations; Genes; Genome; Goals; Gram-Negative Bacteria; Health; Human; IL8 gene; Immune Sera; Immune response; Immunity; In Vitro; Infection; Infection Control; Inflammation; Inflammatory; Interleukin-1; Interleukin-6; Interstitial Pneumonia; Invaded; Knockout Mice; Latex Bead; Ligands; Lung; Mammalian Cell; Mediating; Membrane Proteins; Modeling; Molecular; Morbidity - disease rate; Mus; Open Reading Frames; Pathogenesis; Play; Process; Proteins; Pulmonary Edema; Receptor Cell; Recombinants; Recruitment Activity; Research; Rickettsia; Rickettsia Infections; Rickettsia conorii; Role; Signal Pathway; Site; Skin; Spottings; Surface Antigens; Ticks; United States; Virulence Factors; antimicrobial; congenic; cytokine; human tissue; in vivo; interest; member; mortality; novel; pathogen; programs; receptor; research study; transmission process; uptake

DESCRIPTION (provided by applicant): Rickettsia conorii, a member of the spotted fever group (SFG) rickettsia is an obligate intracellular tick borne pathogen and is the causative agent of Mediterranean spotted fever. Aerosol transmission of rickettsia can occur and therefore, represents a bioterrorist threat for the United States. The pathogenesis of R. conorii upon transmission into the host depends on the pathogen's ability to bind to and invade target host cells. Annotation of several sequenced rickettsial genomes has identified a large family of genes termed surface cell antigens (sca) that resemble autotransporter proteins and virulence factors in Gram-negative bacteria. While many genes in this family are degenerate or split, at least 4 genes, sca0 (rompA), sca1, sca2, and sca5 (rompB) are present as complete open reading frames in R. conorii and many other SFG rickettsia. Previous results have demonstrated that Sca0 (rOmpA) and Sca5 (rOmpB) are important for the adhesion to and subsequent invasion of non-phagocytic mammalian cells and in the generation of protective humoral immune responses. However, very little is known about the function of other outermembrane proteins in SFG rickettsia pathogenesis. We have identified the first rickettsial protein-host cell receptor pair (rOmpB-Ku70) that plays an important role in the establishment of a successful infection within target human cells. Interestingly, our results have also suggested that while rOmpB-Ku70 interactions are important during the invasion process, other conserved SFG rickettsia proteins, namely rOmpA, Sca1 and Sca2, likely play important roles during pathogenesis. The experiments outlined in this proposal will address the following research interests: i. The contributions of rOmpB and Ku70 to colonization will be analyzed by using recombinant E. coli, purified proteins and protein coupled latex beads. The induction of host signaling pathways involved in the uptake process will also be analyzed using a cell culture model. ii. We will determine the contribution of rOmpB and Ku70 to the initiation and progression of SFG rickettsial disease in a murine model of infection using wild-type and Ku70 knockout mice. iii. We will also determine the roles of conserved surface antigens, namely rOmpA, Sca1 and Sca2 in mediating invasion of non-phagocytic mammalian cells. The roles of these proteins in generating protective humoral immune responses will be examined in a murine model of infection. In addition, we will identify novel ligands that interact with these conserved surface proteins in the hopes of identifying new receptors that play roles in the pathogenesis of SFG rickettsia. PUBLIC HEALTH RELEVANCE: Rickettsia conorii, the causative agent of Mediterranean spotted fever, is transmitted by tick bite inoculation into the skin of the human host. Damage to target endothelial cells especially in the lungs and brain can result in the most severe manifestations of disease including pulmonary edema and interstitial pneumonia. Although infections are controlled by broad-spectrum antibiotic therapies, untreated or misdiagnosed Mediterranean spotted fever can results in severe morbidity and mortality. With the threat of the potential use of Rickettsiae and other bacteria as agents for biological terrorism, understanding the complex interplay between the pathogen and host cells is vital for the future development of novel anti-microbials and therapies.

描述（由申请人提供）：Rickettsia conorii，斑点发烧组（SFG）的成员Rickettsia是一种强制性细胞内tick虫发育的病原体，是地中海发现发烧的病原体。可以发生立克的气溶胶传播，因此代表了美国的生物恐怖主义威胁。转移到宿主时，圆锥体的发病机理取决于病原体与靶宿主细胞结合和侵入靶宿主细胞的能力。几个测序的立克基因组的注释已经确定了一个称为表面细胞抗原（SCA）的大家族，它们类似于革兰氏阴性细菌中的自转运蛋白和毒力因子。尽管该家族中的许多基因是退化或分裂的，但至少4个基因，SCA0（ROMPA），SCA1，SCA2和SCA5（ROMPB）作为R. Conorii和许多其他SFG Rickettsia中的完全开放式阅读帧存在。先前的结果表明，SCA0（ROMPA）和SCA5（ROMPB）对于对非噬细胞哺乳动物细胞的粘附和随后的侵袭以及保护性体液免疫反应的产生至关重要。然而，对于其他OUTEREMBRANE蛋白在SFG立克sia发病机理中的功能知之甚少。我们已经确定了第一个立克蛋白宿主宿主受体对（ROMPB-KU70）在靶标人细胞中成功感染中起重要作用的重要作用。有趣的是，我们的结果还表明，虽然ROMPB-KU70相互作用在入侵过程中很重要，但其他保守的SFG Rickettsia蛋白，即Rompa，SCA1和SCA2，在发病机理中可能起重要作用。该提案中概述的实验将解决以下研究兴趣：i。 ROMPB和KU70对定植的贡献将通过使用重组大肠杆菌，纯化的蛋白质和蛋白质耦合乳胶珠来分析。还将使用细胞培养模型分析摄取过程中涉及的宿主信号通路的诱导。 ii。我们将使用野生型和ku70敲除小鼠在鼠类感染模型中确定ROMPB和KU70对SFG立克疾病的起始和进展的贡献。 iii。我们还将确定保守的表面抗原的作用，即Rompa，SCA1和SCA2在介导非吞噬哺乳动物细胞的侵袭中的作用。这些蛋白质在产生保护性体液免疫反应中的作用将在鼠感染模型中检查。此外，我们将确定与这些保守的表面蛋白相互作用的新型配体，以期识别新的受体在SFG人力素的发病机理中起着作用。公共卫生相关性：地中海斑点发烧的病原体立克西亚·康罗伊（Rickettsia conorii）是通过tick咬接种传播到人类宿主皮肤的。靶向内皮细胞的损害，尤其是在肺和大脑中，可能会导致疾病最严重的表现，包括肺水肿和间质性肺炎。尽管感染受到广谱抗生素疗法的控制，但未经治疗或误诊的地中海发现发烧会导致严重的发病率和死亡率。随着可能使用立克西亚和其他细菌作为生物恐怖主义的药物的威胁，了解病原体和宿主细胞之间的复杂相互作用对于新型抗菌和疗法的未来发展至关重要。