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Differential expression of genes encoding membrane proteins between acute and continuous Chlamydia pneumoniae
Richard J Hogan1, Sarah A Mathews, Andrei Kutlin
1Centre for Molecular Biotechnology/Cooperative Research Centre for Diagnostics, School of Life Sciences, Level 5, Q-Block, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4000, Australia.
Abstract:
Chlamydia pneumoniae is associated with several chronic human diseases, including chronic obstructive pulmonary disease and atherosclerotic cardiovascular disease. During chronic disease, organisms are believed to exist in a persistent phase that is not well understood at the genetic level. Long-term in vitro continuous infections are spontaneously persistent and are less susceptible than in vitro acute infections to treatment with antibiotics, and are therefore particularly relevant as an in vitro model of in vivo chronic disease. Real-time reverse transcriptase-PCR (r-t RT-PCR) was used to quantitate transcript copy numbers of 13 genes in continuous and acute infections with C. pneumoniae. The set of genes studied encodes proteins with known or predicted functions in the cell membrane, the inclusion membrane, cell division, metabolism, and immunopathology. Significant upregulation was seen for five genes (CPn0483, nlpD, ompA, pmp1 and porB) in continuous cultures. The genes omcB, pmp1, and porB, all of which encode membrane proteins, shared similar patterns of expression over both acute and continuous profiles. These results show that Chlamydia in the long-term continuous model of persistence have a unique transcription profile, adding to our knowledge of regulation of this important stage of chlamydial growth.
Insights
Chlamydia pneumoniae exhibits unique gene expression during chronic infections. Understanding this persistent phase is crucial for developing effective treatments for associated diseases.
Area of Science:
- Microbiology
- Molecular Biology
- Infectious Diseases
Background:
- Chlamydia pneumoniae is linked to chronic conditions like COPD and cardiovascular disease.
- The genetic basis of C. pneumoniae persistence during chronic infection remains poorly understood.
- Long-term in vitro continuous infections serve as a relevant model for in vivo chronic disease.
Purpose of the Study:
- To investigate the transcriptional profile of C. pneumoniae during persistent infection.
- To identify specific genes with altered expression during chronic C. pneumoniae infection.
Main Methods:
- Quantitative analysis of gene expression using real-time reverse transcriptase-PCR (r-t RT-PCR).
- Comparison of transcript copy numbers for 13 genes between acute and continuous C. pneumoniae infections.
- Genes studied encode proteins involved in cell membrane, inclusion membrane, cell division, metabolism, and immunopathology.
Main Results:
- Five genes (CPn0483, nlpD, ompA, pmp1, porB) were significantly upregulated in continuous (persistent) infections.
- Genes encoding membrane proteins (omcB, pmp1, porB) showed similar expression patterns in both acute and continuous infections.
- C. pneumoniae in long-term continuous culture displays a distinct transcriptional signature.
Conclusions:
- Persistent C. pneumoniae infections exhibit a unique gene transcription profile.
- These findings enhance understanding of the regulatory mechanisms governing chlamydial persistence.
- The study provides insights into the genetic regulation of C. pneumoniae during chronic disease states.