The role of aberrant gene expression in chlamydial persistence and reactivation

项目摘要/摘要： 衣原体目的细菌是真核细胞的胞内寄生虫。他们依靠的是一种 发育周期由网状小体(RB)、中间体(IB)和网状小体(IB)三种细胞形式组成 基本体(EB)。EB是有传染性的，但不会复制。RB在宿主细胞中复制，但 非传染性，而IB是过渡到EB形式的中间形式。完成这一开发- 精神周期是衣原体致病的核心。在这个目中，衣原体属包含 一些人类重要病原体的病原体。鹦鹉热引起人畜共患感染结果- 肺炎链球菌是一种可引起呼吸道疾病的人类病原体，与 动脉硬化。沙眼衣原体生物群是沙眼的病原体，是导致沙眼前期肺炎的主要原因。 全世界范围内的呼吸性失明，以及性传播疾病衣原体。无论结果如何- 在疾病中，所有衣原体物种都具有相同的专性细胞内生命周期和发育周期。 衣原体发育周期通过退出发育周期而对环境压力做出反应 形成“异常”的细胞形态，延缓感染性EBS的产生。然后，这些单元格表单可以重新进入 环境压力解除时的生产发展周期。据推测，这一重新- 应激条件有助于临床观察衣原体感染通常是慢性或 在相当数量的确诊病例中再次发生。我们已经开发了一个活细胞记者系统来跟踪 在单包涵体水平上实时进行细胞类型转换，并确定衣原体对应激的反应 在不同的治疗方法和不同的时间里，如肽聚糖抑制剂或营养应激等条件是不同的。招待- 与肽聚糖抑制剂联合治疗会导致RB到IB的发育受阻，产生异常的多倍体RBS。 这些异常细胞在表达IB报告器之前表达RB报告器约10小时，但从未表达过 要么向EB记者施压，要么获得传染性。营养胁迫，如色氨酸和铁饥饿，也有报道。 导致衣原体退出生产发育周期，形成“异常”的RBS。我们的实时细胞数据 这表明这些细胞不会表现出与那些用肽聚糖抑制剂处理的细胞相同的表型。 因此，目标1将确定反应的异常RBS的表型和基因表达谱。 产生具有传染性的EBS。从IB到EB的发展是一个缓慢的过程，需要大约10个小时才能达到最大EB 报告基因的表达。因此，我们假设IB可能通过停止去磷而对营养胁迫作出反应。 生长发育，直到营养胁迫被解决。然后IB可以重新进入生产的发育状态 有传染性的后代。因此，目标2将确定IB对EB转变的贡献。 坦斯。

Project Summary/Abstract: The bacteria in the Chlamydiales order are intracellular parasites of eukaryotic cells. They are reliant on a de- velopmental cycle consisting of three cell forms termed the reticulate body (RB), the intermediate body (IB) and the elementary body (EB). The EB is infectious but does not replicate. The RB replicates in the host cell but is non-infectious, while the IB is an intermediate form that transitions to the EB form. Completion of this develop- mental cycle is central to chlamydial pathogenesis. Within this order, the genus Chlamydia contains the causative agents of a number of important pathogens of humans. C. psittaci causes zoonotic infections result- ing in pneumonia, while C. pneumoniae is a human pathogen that causes respiratory disease and is linked to atherosclerosis. Biovars of C. trachomatis are the causative agents of trachoma, the leading cause of pre- ventable blindness worldwide, as well as the sexually transmitted disease Chlamydia. Irrespective of the result- ing disease, all chlamydial species share the same obligate intracellular life cycle and developmental cycle. The chlamydial developmental cycle reacts to environmental stresses by exiting the developmental cycle and forming “aberrant” cell forms and delaying the production of infectious EBs. These cell forms can then reenter the productive developmental cycle when the environmental stress is lifted. It is hypothesized that this re- sponse to stress conditions contributes to the clinical observation that chlamydial infections are often chronic or reoccur in a significant number of diagnosed cases. We have developed a live-cell reporter system to follow cell-type switching in real time at the single inclusion level and determined that Chlamydia’s response to stress conditions such as peptidoglycan inhibitors or nutrient stress differs between treatments and over time. Treat- ment with peptidoglycan inhibitors results in a block in RB to IB development creating aberrant polyploid RBs. These aberrant cells express the RB reporter for ~ 10 hours prior to expressing the IB reporter but never ex- press EB reporters or gain infectivity. Nutrient stress such as tryptophan and iron starvation are also reported to cause Chlamydia to exit the productive developmental cycle and form “aberrant” RBs. Our live cell data suggests that these cells do not exhibit the same phenotype as those treated with peptidoglycan inhibitors. Therefore Aim 1 will Determine the phenotype and gene expression profile of aberrant RBs that reacti- vate to produce infectious EBs. IB to EB development is a slow process taking ~10 hours until maximal EB reporter gene expression. We therefore hypothesize that the IB may respond to nutrient stress by halting de- velopment until the nutrient stress is resolved. The IB then could reenter the developmental state producing infectious progeny. Therefore Aim 2 will Determine the contribution of the IB to EB transition in persis- tence.