Molecular-genetic analysis of TB persistence and latency

结核病持续性和潜伏期的分子遗传学分析

• 批准号: 6901858
• 负责人: John D. McKinney
• 金额: $ 40.63万
• 依托单位: ROCKEFELLER UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6901858
• 关键词: African; Mycobacterium tuberculosis; bacterial genetics; clinical research; disease /disorder model; gene expression; gene mutation; genetic screening; host organism interaction; human subject; laboratory mouse; latent bacterial disease; polymerase chain reaction; tuberculosis

DESCRIPTION (provided by applicant): Tuberculosis (TB) is rivaled only by AIDS as a communicable cause of death. Infection is lifelong and may reactivate following an asymptomatic (latent) interval of variable duration. It is estimated that nearly two billion individuals worldwide have been exposed to Mycobacterium tuberculosis. Exposed (tuberculin-positive) individuals have a 5-10% lifetime risk of developing active TB. The risk rises to nearly 10% per year for individuals with HIV/AIDS, indicating a key role for the host immune response in maintaining TB latency. Chemoprophylaxis of latent TB to prevent reactivation requires months of drug therapy, a regimen that many individuals are unwilling or unable to complete. The development of better tools for TB control will hinge on the elucidation of the adaptive mechanisms that allow latent M. tuberculosis to persist in the face of host immunity and chemotherapy. Towards that goal, this application is focused on the identification of mycobacterial "persistence factors" and "defense factors" via signature-tagged mutagenesis (STM), a method for simultaneous screening of multiple mutants in mice. Two genetic screens are described. The persistence (per) screen will identify M. tuberculosis mutants that are specifically impaired in their ability to persist at later stages of infection in mice. The defense (def) screen will identify mutants whose attenuated phenotype in immune-competent mice is reversed in mice with specific immune deficiencies. These screens will identify mycobacterial genes involved in long-term persistence and defense against host immune mechanisms, respectively. The role of these genes in latent persistence will be assessed in the "Cornell model" of chemotherapy-induced latency and reactivation in mice. Our studies in the mouse will serve as a springboard for linked studies in humans. Relevance to human infection will be explored by analyzing the expression of per/def genes in the lungs of mice and humans via real-time RT-PCR with molecular beacons. Bacterial correlates of protection and pathogenesis will be identified by comparison of gene expression profiles in latent v. active human lesions, respectively. These studies will elucidate the host/pathogen interactions that determine the state of infection-latency or active disease-and may point the way to novel interventions against TB.

描述（由申请人提供）： 作为一种传染性死亡原因，结核病 (TB) 仅次于艾滋病。 感染是终生的，并且可能在无症状（潜伏）后重新激活 可变持续时间的间隔。估计有近二十亿 全世界都有人接触过结核分枝杆菌。裸露 （结核菌素阳性）个体终生有 5-10% 的患病风险 活动性结核病。对于患有此病的个人来说，这种风险每年增加近 10% HIV/艾滋病，表明宿主免疫反应在维持结核病方面发挥着关键作用 延迟。对潜伏结核病进行化学预防以防止其重新激活需要数月时间 药物治疗，这是许多人不愿意或无法进行的治疗方案 完全的。开发更好的结核病控制工具将取决于 阐明潜伏结核分枝杆菌的适应性机制 面对宿主免疫和化疗坚持不懈。为了这个目标，这 应用重点是分枝杆菌“持久性”的鉴定 通过签名标记诱变（STM）的“因子”和“防御因子”， 在小鼠体内同时筛选多个突变体的方法两个遗传 屏幕进行了描述。持久性（每）屏幕将识别 M。 结核病突变体的能力特别受损 在小鼠感染后期持续存在。防御（def）屏幕将 鉴定出在免疫活性小鼠中减毒表型的突变体 在患有特定免疫缺陷的小鼠中，这种情况发生了逆转。这些屏幕将 识别参与长期持久性和防御的分枝杆菌基因 分别针对宿主免疫机制。这些基因的作用 将在化疗引起的“康奈尔模型”中评估潜在的持久性 小鼠的潜伏期和重新激活。我们对小鼠的研究将有助于 作为人类相关研究的跳板。与人类感染的相关性 将通过使用分子信标的实时 RT-PCR 分析小鼠和人类肺部中 per/def 基因的表达来探索。细菌 将通过比较确定保护和发病机制的相关性 分别在人类潜在病变和活动性病变中的基因表达谱。 这些研究将阐明决定宿主/病原体的相互作用 感染状态——潜伏期或活动性疾病——并可能为新的发现指明道路 结核病干预措施。