Expression of Chlamydia trachomatis genes encoding products required for DNA synthesis and cell division during active versus persistent infection

Abstract

SummaryDuring 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 ¼ 0 -48 h post-infection (p.i.; active). Human monocytes were infected similarly and harvested at t ¼ 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.

Molecular Mimicry of an HLA-B27-derived Ligand of Arthritis-linked Subtypes with Chlamydial Proteins

“…Therefore, peptides produced by degradation of this protein might be available soon for presentation on infected cells. It is also noteworthy that, contrary to other genes such as those involved in cytokinesis, bacterial genes involved in DNA replication are expressed during chlamydial persistence, in which the bacteria modify their cell cycle and survive into the cytoplasmic inclusions of the host cell (65). Persistent Chlamydiae may be the dominant forms in the joints of ReA patients, where they might be a source of chronic antigenic stimulation.…”

Effect of the steroid receptor antagonist RU486 (mifepristone) on an IFNγ-induced persistent Chlamydophila pneumoniae infection model in epithelial HEp-2 cells

“…The expression level for this target molecule appears to be arrested in persistent infection, implying that the molecule is directly associated with bacterial maturation through acceleration of the developmental cycle. The alteration of chlamydial gene expression in the persistent infection was well documented [16,17,26,29]. In particular, the persistent stage of the bacteria was characterized by the downregulation of a broad range of genes, associating with metabolism and cell division; in contrast the genes regulating DNA repair and replication were normally expressing even in the persistent stage [29].…”

“…Therefore, whether the drug could modify bacterial gene expression of 16S rRNA and hsp60, which are essential for all metabolically active stages of C. pneumoniae, including noninfectious RBs in infected cells [15,20,29], was assessed by RT-PCR analysis, with determining inclusion formation and the number of infectious progenies. However, interestingly, our data indicated a possibility that these gene expression were unlikely to enough reflect bacterial viability in persistent stage induced by IFN, although further study for seeking more appropriate gene makers reflecting bacterial viability in the stage should be needed.…”

“…The alteration of chlamydial gene expression in the persistent infection was well documented [16,17,26,29]. In particular, the persistent stage of the bacteria was characterized by the downregulation of a broad range of genes, associating with metabolism and cell division; in contrast the genes regulating DNA repair and replication were normally expressing even in the persistent stage [29]. Therefore, it is possible that these genes regarding metabolism and/or cell division are attractive candidates as target molecule of RU486, although further study should be needed.…”

Role of Chlamydia in the Development of Ocular Adnexal Lymphoma

“…Under in vitro conditions, RBs block division and maintain a stable association with the infected cell and become the "aberrant" or persistent bodies with enlarged forms, altered gene expression profile and multiple nucleoids instead of undergoing rapid replication and differentiating into infectious EBs. During persistent growth, aberrant RBs continue chromosome replication but fail to divide [36]. These events constitute the basis of clinical persistence leading to chronic sequelae.…”