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Updated: Jun 19, 2025
09:03
Forward Genetic Approaches in Chlamydia trachomatis
Published on: October 23, 2013
12.9K
Chlamydia suis undergoes interclade recombination promoting Tet-island exchange
Helena Seth-Smith1, Sankhya Bommana2, Deborah Dean2,3
1Institute of Veterinary Pathology, University of Zurich, Zurich, Switzerland.
BMC Genomics
|July 26, 2024
Summary
Tetracycline resistance in Chlamydia suis arose from a single horizontal gene transfer event. Interclade recombination of the tetracycline resistance (TetR) island occurred after this event, with variations observed between field and in vitro strains.
Area of Science:
- Bacterial genomics
- Antimicrobial resistance evolution
- Molecular evolution
Background:
- Chlamydiaceae are obligate intracellular bacteria causing various diseases.
- Chlamydia suis is unique in naturally acquiring tetracycline resistance (TetR) via a genomic island (Tet-island).
- The Tet-island is integrated within the invasin-like gene (inv) in C. suis.
Purpose of the Study:
- To investigate the interclade recombination of the Tet-island in C. suis field strains.
- To compare recombination patterns between field strains and in vitro-generated recombinants.
- To understand the evolutionary dynamics of tetracycline resistance acquisition in C. suis.
Main Methods:
- Comparative genomic analysis of whole genome sequences.
- Phylogenetic analysis of the invasin-like gene (inv) and the Tet-island.
- Analysis of recombination patterns in 35 C. suis field strains and 63 in vitro-generated recombinants.
Main Results:
- The phylogeny of inv more closely mirrored the Tet-island phylogeny than the whole genome, supporting recombination as the transfer mechanism.
- Significant differences in recombination distribution were observed between in vitro and field strains.
- Interclade recombination events involving the Tet-island showed greater variability in length downstream compared to upstream.
Conclusions:
- The study supports a single ancestral horizontal gene transfer event for the Tet-island.
- Interclade recombination explains the presence of tetracycline resistance in both C. suis clades.
- Understanding these recombination events is crucial for tracking antimicrobial resistance in Chlamydia.
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