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Evolution of a pathogen: a comparative genomics analysis identifies a genetic pathway to pathogenesis in
Jason W Sahl1, John D Gillece, James M Schupp
1Department of Pathogen Genomics, Translational Genomics Research Institute, Flagstaff, Arizona, United States of America. jsahl@tgen.org
Plos One
|February 1, 2013
Summary
Genomic analysis reveals that Acinetobacter baumannii
Area of Science:
- Microbiology
- Genomics
- Evolutionary Biology
Background:
- Acinetobacter baumannii is a significant global nosocomial pathogen.
- Other Acinetobacter species, particularly within the Acinetobacter calcoaceticus-baumannii (Acb) complex, are linked to severe human infections.
- The genetic drivers behind A. baumannii's widespread virulence remain incompletely understood.
Purpose of the Study:
- To conduct a comprehensive genomic comparison across the Acinetobacter genus.
- To identify gene acquisition and loss events contributing to the genus's expansion.
- To elucidate the evolutionary basis of A. baumannii's emergence as a dominant pathogen.
Main Methods:
- Whole genome sequencing of 136 Acinetobacter isolates, including 67 newly sequenced genomes.
- Phylogenetic analysis to establish evolutionary relationships within the Acinetobacter genus.
- Blast Score Ratio (BSR) analysis for global genomic feature comparison.
Main Results:
- Whole genome phylogeny confirmed A. baumannii as a monophyletic clade and the Acb complex as a well-supported monophyletic group.
- BSR analysis revealed significant gene loss and acquisition during A. baumannii evolution.
- Virulence-associated genes are more conserved in the Acb complex and A. baumannii compared to other Acinetobacter species.
Conclusions:
- Acquisition of specific virulence factors likely underpins the persistence and virulence of A. baumannii.
- Novel transcriptional regulatory features identified in the Acb complex offer targets for understanding virulence evolution.
- Comparative genomics provides insights into the diversification and pathogenic potential within the Acinetobacter genus.
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