Virulence of the Opportunistic Pathogen Rhodococcis Equi

机会性病原体马红球菌的毒力

• 批准号: 7343180
• 负责人: MARY HONDALUS
• 金额: $ 31.55万
• 依托单位: UNIVERSITY OF GEORGIA
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-02-01 至 2011-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7343180
• 关键词: Actinobacteria class; Actinomyces; Address; Affect; Attenuated; Bacteria; Binding; Binding Sites; Biological Assay; Biology; Breathing; Cellular biology; Clinical; Complex; Data; Defect; Development; Disease; Disruption; Epidemic; Event; Gene Family; Genes; Genetic; Goals; Granulomatous; Growth; HIV; High temperature of physical object; Homologous Gene; Host Defense; Immunity; In Vitro; Individual; Infection; Inflammation; Investigation; Ions; Knowledge; Life; Light; Lipoproteins; Location; Lysosomes; Macrophage Cell Biology; Malignant Neoplasms; Methods; Molecular; Molecular Mechanisms of Action; Monitor; Mus; Mutagenesis; Mycobacterium tuberculosis; Nature; Obstruction; Oxidative Stress; Pathogenesis; Pathway interactions; Persons; Phagocytosis; Phagosomes; Phenotype; Physiology; Plasmids; Pneumonia; Positioning Attribute; Process; Production; Proteins; Recombinants; Regulation; Regulatory Pathway; Regulon; Reporter; Research; Research Personnel; Resources; Rhodococcus equi; Role; Signal Transduction; Soil; Stimulus; Sum; Surface; System; Temperature; Testing; Time; Virulence; Work; attenuation; base; chemotherapy; expectation; genetic analysis; genetic manipulation; in vivo; innovation; insight; intracellular parasitism; killings; macrophage; member; mortality; mouse model; mutant; novel; pathogen; programs; promoter; resistance factors; response; tool; trafficking

With the arrival of the HIV epidemic and the increase in individuals undergoing chemotherapy for various cancers, the understudied zoonotic opportunistic pathogen Rhodococcus equi has emerged as cause of life- threatening pneumonia in persons of compromised immunity. Rhodococcal pneumonia is characterized by pyogranulomatous inflammation with cavitation, which can be misdiagnosed as Mycobacterium tuberculosis infection. R. equi is a common soil-borne facultative actinomycete which, when inhaled, resists innate killing mechanisms and readily multiplies in macrophages of susceptible hosts, likely by perturbation of endosomal trafficking. Little is known about the molecular basis for R. equi pathogenesis, and prior to our recent work, few tools existed to allow a thorough genetic analysis of this bacterium. Recently, we have developed the genetic methods to construct defined mutants of R. equi and have also created an efficient transposon mutagenesis system. Using these new tools, we demonstrated that vapA (virulence associated p/otein A), a gene present on the virulence plasmid of R. equi, is required for intracellular growth and full virulence. Deletion of vapA attenuates the bacterium, rendering it incapable of growth in vivo and unable to replicate in macrophages cultured in vitro. Our long-term goal is to completely dissect the genetic basis for R. equi virulence. We propose to do so by first expanding our understanding of vapA, which is to date the only known R. equi virulence determinant. The first AIM of this work is to identify the mechanism of action of vapA. To do so, we will define the intracellular events post phagocytosis of both wild type R. equi and the vapA deletion mutant. Specifically we will characterize the process of phagosomal maturation in wild type R. equi infected macrophages and test the influence of VapA on phagosome acidification and fusion with lysosomes. We will identify interacting host protein partners of VapA. The second AIM is to characterize the R. equi virulence regulon through the examination of regulators of vapA expression, VirR (yjrulence regulator) and VarA (yap regulator). We will identify the specific signals transduced by these regulators and identify additional genes controlled by them. We will establish the effects of deletion mutants of virR and varA on R. equi virulence. Finally, we will identify the binding sites of the regulators to the vapA promoter. These studies addressing the molecular mechanisms of R. equi pathogenesis will further our understanding of macrophage cell biology and will yield insight into the biology of actinomycete host-pathogen relationships in general.

随着艾滋病毒疫情的到来和因各种原因接受化疗的人数增加 癌症，一种未被研究的人畜共患机会性病原体马红球菌已经成为生命的原因-- 免疫力低下者的威胁肺炎。流行性肺炎的特点是 伴有空洞的化脓性肉芽肿性炎症可误诊为结核分枝杆菌 感染。马立克氏杆菌是一种常见的土壤传播的兼性放线菌，当被吸入时，它能抵抗先天死亡。 易感宿主巨噬细胞的机制和易增殖，可能是由于内体的扰动 贩卖人口。对马立克氏杆菌致病的分子基础知之甚少，在我们最近的工作之前， 几乎没有工具可以对这种细菌进行彻底的基因分析。最近，我们开发了 构建马立克氏杆菌明确突变体的遗传方法，也创造了一个有效的转座子 诱变系统。使用这些新工具，我们证明了VapA(毒力相关p/otein A)，a 马立克氏杆菌毒力质粒上存在的基因是细胞内生长和完全毒力所必需的。 VapA的缺失会削弱细菌，使其不能在体内生长，也不能在体内复制 巨噬细胞体外培养。我们的长期目标是彻底剖析马立克氏杆菌的遗传基础 致命性。我们建议这样做，首先扩大我们对VapA的理解，这是迄今为止唯一的 已知的马立克氏杆菌毒力决定因素。这项工作的第一个目的是确定其作用机制。 蒸气。为此，我们将定义野生型马立克氏杆菌和马立克氏杆菌吞噬后的细胞内事件。 VapA缺失突变体。具体地说，我们将描述野生型R。 等感染巨噬细胞并检测VapA对吞噬小体酸化和融合的影响 溶酶体。我们将确定VapA相互作用的宿主蛋白伙伴。第二个目标是描述 通过检测VapA表达调节子Virr(Yjrulence)的毒力调节子 调节器)和VARA(YAP调节器)。我们将识别这些调节器传递的特定信号，并 确定由它们控制的其他基因。我们将建立病毒和病毒缺失突变体的影响 马立克氏杆菌致病力的变异。最后，我们将确定调节子与VapA启动子的结合位点。 这些针对马立克氏杆菌致病分子机制的研究将进一步加深我们对马立克氏杆菌致病机理的理解。 巨噬细胞生物学，并将深入了解放线菌宿主与病原体的生物学关系 总体而言。