Virulence of the Opportunistic Pathogen Rhodococcis Equi

机会性病原体马红球菌的毒力

• 批准号: 7758845
• 负责人: MARY HONDALUS
• 金额: $ 31.23万
• 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 2013-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7758845
• 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; 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; 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; Tuberculosis; 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.

随着艾滋病毒流行的到来以及接受各种化疗的人数增加 癌症中，尚未得到充分研究的人畜共患机会致病菌马红球菌已成为导致生命的原因—— 免疫力低下的人可能会患上肺炎。红球菌肺炎的特点是 脓性肉芽肿性炎症伴空洞，可误诊为结核分枝杆菌 感染。马罗氏菌是一种常见的土传兼性放线菌，吸入后可抵抗先天杀伤 机制并很容易在易感宿主的巨噬细胞中繁殖，可能是通过内体的扰动 贩运。人们对马罗氏菌发病机制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遗传分析。最近，我们开发了 遗传方法构建了马罗氏菌的确定突变体，并创建了有效的转座子 诱变系统。使用这些新工具，我们证明了 vapA（毒力相关 p/otein A），一种 马罗氏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 的缺失会削弱细菌的活性，使其无法在体内生长，也无法在体内复制。 体外培养的巨噬细胞。我们的长期目标是彻底剖析 R.equito 的遗传基础 毒力。我们建议首先扩大我们对 vapA 的理解，这是迄今为止唯一的 已知R.equi毒力决定因素。这项工作的第一个目的是确定作用机制 蒸气A。为此，我们将定义野生型马马和马马的吞噬作用后的细胞内事件 vapA 缺失突变体。具体来说，我们将描述野生型 R 中吞噬体成熟的过程。 马感染巨噬细胞并测试VapA对吞噬体酸化和融合的影响 溶酶体。我们将鉴定 VapA 的相互作用宿主蛋白伙伴。第二个目标是描述 R. equal 毒力调节通过 vapA 表达调节因子 VirR (yjrulence 调节器）和 VarA（yap 调节器）。我们将识别这些调节器传导的特定信号，并 识别由它们控制的其他基因。我们将确定 virR 和 virR 缺失突变体的影响 varA 对 R. equal 毒力。最后，我们将确定调节因子与 vapA 启动子的结合位点。 这些针对马罗氏菌发病机制的分子机制的研究将进一步加深我们的理解 巨噬细胞细胞生物学，并将深入了解放线菌宿主-病原体关系的生物学 一般来说。

项目成果

Conjugal transfer of a virulence plasmid in the opportunistic intracellular actinomycete Rhodococcus equi.

机会性细胞内放线菌马红球菌中毒力质粒的接合转移。

• DOI: 10.1128/jb.01210-12
• 发表时间: 2012
• 期刊: Journal of bacteriology
• 影响因子: 3.2
• 作者: Tripathi,VN;Harding,WC;Willingham-Lane,JM;Hondalus,MK
• 通讯作者: Hondalus,MK

Site-specific integration of Streptomyces PhiC31 integrase-based vectors in the chromosome of Rhodococcus equi.

• DOI: 10.1111/j.1574-6968.2008.01298.x
• 发表时间: 2008-10
• 期刊: FEMS microbiology letters
• 影响因子: 2.1
• 作者: Hong Y;Hondalus MK
• 通讯作者: Hondalus MK

IcgA is a virulence factor of Rhodococcus equi that modulates intracellular growth.

IcgA 是马红球菌的毒力因子，可调节细胞内生长。

• DOI: 10.1128/iai.01670-13
• 发表时间: 2014
• 期刊: Infection and immunity
• 影响因子: 3.1
• 作者: Wang,Xiaoguang;Coulson,GarryB;Miranda-Casoluengo,AleksandraA;Miranda-Casoluengo,Raúl;Hondalus,MaryK;Meijer,WimG
• 通讯作者: Meijer,WimG