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Live-Cell Forward Genetic Approach to Identify and Isolate Developmental Mutants in Chlamydia trachomatis
Published on: June 10, 2020
Evolutionary dynamics of ompA, the gene encoding the Chlamydia trachomatis key antigen
Alexandra Nunes1, Maria J Borrego, Baltazar Nunes
1Department of Infectious Diseases, National Institute of Health, Lisbon, Portugal.
Journal of Bacteriology
|September 29, 2009
Summary
Host immune pressure drives mutations in Chlamydia trachomatis major outer membrane protein (MOMP), particularly in antigenic regions. Successful genotypes exhibit lower mutation rates, suggesting enhanced immune system evasion.
Area of Science:
- Microbiology
- Immunology
- Evolutionary Biology
Background:
- Chlamydia trachomatis is a leading cause of bacterial sexually transmitted infections and trachoma globally.
- The major outer membrane protein (MOMP) is a key antigen, acting as a porin and adhesin, with its variability previously studied mainly for epidemiological purposes.
Purpose of the Study:
- To investigate the evolutionary dynamics of Chlamydia trachomatis MOMP under host immune pressure.
- To analyze the impact of mutations on MOMP's secondary structure and antigenic regions in urogenital Chlamydia trachomatis isolates.
Main Methods:
- Analysis of evolutionary dynamics of MOMP in 795 urogenital Chlamydia trachomatis isolates.
- Consideration of MOMP secondary structure and antigenic region locations.
- Comparison of mutation rates between different genotypes.
Main Results:
- One-third of isolates showed mutations not previously described, with amino acid alterations sixfold more frequent in B-cell epitopes.
- The most successful genotypes (E and F) had significantly lower mutation rates (60.3-fold lower) than other genotypes.
- Mutations were observed near T-cell antigenic clusters and within residues critical for porin function, suggesting adaptation for stability and flexibility.
Conclusions:
- Host immune pressure significantly influences MOMP evolution, favoring mutations in antigenic regions.
- Lower mutation rates in successful genotypes (E and F) suggest superior immune evasion capabilities rather than specific virulence factors.
- MOMP plasticity allows adaptation to environmental pressures, potentially enhancing chlamydial infectivity, persistence, and transmission.
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