M.tuberculosis Rpfs: Modulators of Reactivation

结核分枝杆菌 Rpfs：再激活调节剂

• 批准号: 7230029
• 负责人: JOANN M TUFARIELLO
• 金额: $ 24.18万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 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 2009-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7230029
• 关键词: Acquired Immunodeficiency Syndrome; Acute; Address; Bacillus (bacterium); Bacteria; Behavior; Calmette-Guerin Bacillus; Cause of Death; Cessation of life; Chromosomes; Chronic; Chronic Phase; Clinical; Count; Defect; Disease; Epidemic; Figs - dietary; Gene Expression Profile; Gene Family; Generations; Genes; Genus Mycobacterium; Growth; HIV Infections; Homologous Gene; Human; Hypoxia; Immune; Immune response; Immune system; Immunocompetent; In Vitro; Individual; Infection; Integration Host Factors; Kinetics; Knock-out; Knowledge; Lead; Left; Light; Micrococcus luteus; Mitosis; Modeling; Molecular; Multigene Family; Mus; Mycobacterium tuberculosis; Nitric Oxide Synthase; Organism; Pathogenesis; Personal Satisfaction; Persons; Phase; Phenotype; Physiological; Play; Population; Process; Proteins; Publications; Rate; Recrudescences; Resuscitation; Risk; Role; Steroids; System; Therapeutic Intervention; Tissues; Tuberculosis; burden of illness; cytokine; genome sequencing; in vivo; inhibitor/antagonist; latent infection; lifetime risk; mortality; mouse model; mutant; mycobacterial; novel; novel therapeutics; pathogen; reactivation from latency; response; senescence; therapeutic target

DESCRIPTION (provided by applicant): Tuberculosis (TB) is the leading cause of death due to a single bacterial pathogen. The AIDS epidemic has impacted the resurgence of TB, as HIV-infected persons have a 10% annual risk of reactivation vs. an -10% lifetime risk for immunocompetent persons. Since one-third of the world's population is infected with Mycobacterium tuberculosis (Mtb) and at risk for reactivation, it is crucial that the burden of latent infection be addressed if attempts to control the TB epidemic are to succeed. Despite the centrality of reactivation in Mtb pathogenesis, little is known about the mechanisms which maintain latency and permit the later recrudescence of disease. In particular, bacterial factors at play in re-emergence from dormancy remain elusive. Mtb encodes five genes with homology to the resuscitation-promoting factor (Rpf) of Micrococcus luteus. Rpf is a 16 kDa secreted protein which stimulates a 1000-fold increase in colony counts when added to "dormant" M. luteus. Mtb Rpfs also stimulate growth of stationary phase M. bovis BCG in vitro, yet the in vivo role of this gene family remains incompletely defined. I observed that rpfs can be deleted individually from the Mtb chromosome without obvious growth defects in vitro or in vivo, during acute infection. I have now found, using a murine TB latency model, that the Mtb Rv1009 (rpf) deletion mutant shows markedly delayed kinetics of reactivation following administration of a nitric oxide synthase inhibitor. To our knowledge this is the first Mtb mutant with a specific in vivo defect in reactivation. Fuller understanding of this phenotype should shed light on mechanisms of mycobacterial dormancy and reactivation, and may offer novel therapeutic targets. This proposal addresses the hypothesis that Rv1009 is a secreted factor which stimulates reactivation of "dormant" bacilli and examines the delayed reactivation phenotype of the Rv1009 mutant from three points of view: characterizing the underlying immune mechanisms using murine models of reactivation, exploring an anaerobic dormancy model as an in vitro correlate, and determining whether multi- Rpf knockouts display delayed reactivation. Relevance: Tuberculosis (TB) causes 2 million deaths per year. M. tuberculosis (Mtb) can remain dormant within infected individuals for decades before reactivating to cause disease. Because a better understanding of the reactivation process is critical to control of TB, this proposal focuses on an Mtb gene family believed to play a role in regulating reactivation from the dormant state.

描述（由申请人提供）：结核病（TB）是由单一细菌病原体引起的主要死亡原因。艾滋病的流行影响了结核病的死灰复燃，因为艾滋病毒感染者的年复燃风险为10%，而免疫能力正常的人的终生复燃风险为-10%。由于世界上三分之一的人口感染了结核分枝杆菌（Mtb）并有重新激活的风险，因此，如果要成功控制结核病流行的努力，就必须解决潜伏感染的负担。尽管再激活在结核分枝杆菌发病机制中处于中心地位，但对于维持潜伏并允许疾病后期复发的机制知之甚少。特别是，细菌因素在从休眠中重新出现的作用仍然难以捉摸。结核分枝杆菌编码5个与黄体微球菌复苏促进因子（Rpf）同源的基因。Rpf是一种16 kDa的分泌蛋白，当添加到“休眠”的M. luteus时，刺激菌落计数增加1000倍。Mtb Rpfs在体外也能刺激固定期牛分枝杆菌BCG的生长，但该基因家族在体内的作用仍不完全明确。我观察到，在体外或体内，急性感染期间，Mtb染色体上的rpfs可以被单独删除，而没有明显的生长缺陷。我现在发现，使用小鼠结核潜伏期模型，Mtb Rv1009 （rpf）缺失突变体在给予一氧化氮合酶抑制剂后表现出明显延迟的再激活动力学。据我们所知，这是第一个具有特异性体内再激活缺陷的Mtb突变体。对这种表型更全面的了解将有助于阐明分枝杆菌休眠和再激活的机制，并可能提供新的治疗靶点。本研究提出了Rv1009是一种刺激“休眠”杆菌再激活的分泌因子的假设，并从三个方面考察了Rv1009突变体的延迟再激活表型：利用小鼠再激活模型表征潜在的免疫机制，探索厌氧休眠模型作为体外相关性，并确定多Rpf敲除是否显示延迟再激活。相关性：结核病每年造成200万人死亡。结核分枝杆菌（Mtb）可以在感染者体内潜伏数十年，然后重新激活并引起疾病。由于更好地了解再激活过程对控制结核病至关重要，因此本研究将重点放在一个被认为在调节从休眠状态再激活中起作用的结核分枝杆菌基因家族上。