Gérard H C, Krausse-Opatz B, Wang Z, Rudy D, Rao J P, Zeidler H, Schumacher H R, Whittum-Hudson J A, Köhler L, Hudson A P
Department of Immunology and Microbiology, Wayne State University School of Medicine, Gordon H. Scott Hall, 540 East Canfield Ave., Detroit, MI 48201, USA.
Mol Microbiol. 2001 Aug;41(3):731-41. doi: 10.1046/j.1365-2958.2001.02550.x.
During persistent infection, the intracellular bacterial pathogen Chlamydia trachomatis is viable but severely attenuates the production of new, infectious elementary bodies (EBs). To investigate the reasons for this lack of new EB output, we analysed the expression of chlamydial genes encoding products required for DNA replication and cell division, using in vitro models of active versus persistent infection and synovial tissue samples from patients with chronic Chlamydia-associated arthritis. Hep-2 cells were infected with K serovar C. trachomatis and harvested at t = 0-48 h post-infection (p.i; active). Human monocytes were infected similarly and harvested at t = 1-7 days p.i. (persistent). RNA preparations from infected/uninfected cells and patient samples were subjected to reverse transcription-polymerase chain reaction (RT-PCR) targeting polA, dnaA, mutS and parB mRNA, related to chlamydial DNA replication/segregation; these were expressed in infected Hep-2 cells from 11 to 48 h p.i; ftsK and ftsW, related to cell division, were expressed similarly. Real-time PCR analyses demonstrated that significant accumulation of chlamydial chromosome began at about 12 h p.i. in infected Hep-2 cells. In infected human monocytes, polA, dnaA, mutS and parB mRNA were produced from days 1-7 p.i. and were weakly expressed in patient samples. Real-time PCR indicated the continuing accumulation of chlamydial chromosome during the 7 day monocyte infection, although the rate of such accumulation was lower than that occurring during active growth. However, transcripts from ftsK and ftsW were detected only at 1 day p.i. in infected monocytes but not thereafter, and they were absent in all patient samples. Thus, genes whose products are required for chlamydial DNA replication are expressed during persistence, but transcription of genes whose products are required for cytokinesis is severely downregulated. These data explain, at least in part, the observed attenuation of new EB production during chlamydial persistence.
在持续性感染期间，细胞内细菌病原体沙眼衣原体仍具有活力，但会严重减弱新的感染性原体（EB）的产生。为了探究新EB产量不足的原因，我们利用活跃感染与持续性感染的体外模型以及慢性衣原体相关关节炎患者的滑膜组织样本，分析了编码DNA复制和细胞分裂所需产物的衣原体基因的表达情况。用K血清型沙眼衣原体感染Hep-2细胞，并在感染后（p.i.；活跃期）0至48小时收获。以类似方式感染人单核细胞，并在感染后1至7天收获（持续性）。对感染/未感染细胞及患者样本的RNA制剂进行逆转录聚合酶链反应（RT-PCR），靶向与衣原体DNA复制/分离相关的polA、dnaA、mutS和parB mRNA；这些基因在感染后的Hep-2细胞中于感染后11至48小时表达；与细胞分裂相关的ftsK和ftsW也有类似表达。实时PCR分析表明，衣原体染色体在感染后的Hep-2细胞中约12小时开始显著积累。在感染的人单核细胞中，polA、dnaA、mutS和parB mRNA在感染后1至7天产生，并在患者样本中弱表达。实时PCR表明，在单核细胞感染的7天期间，衣原体染色体持续积累，尽管这种积累速度低于活跃生长期间。然而，ftsK和ftsW的转录本仅在感染的单核细胞感染后1天被检测到，之后未再检测到，且在所有患者样本中均不存在。因此，衣原体DNA复制所需产物的基因在持续性感染期间表达，但胞质分裂所需产物的基因转录严重下调。这些数据至少部分解释了在衣原体持续性感染期间观察到的新EB产生的减弱现象。
