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Elucidating the molecular mechanisms of bacterial virulence using non-mammalian hosts
S Mahajan-Miklos1, L G Rahme, F M Ausubel
1Microbia Inc., One Kendall Square Building 1400W, Suite 1418, Cambridge, MA 02139, USA.
Abstract:
Several strains of the human opportunistic pathogen Pseudomonas aeruginosa infect plants, nematodes and insects. Our laboratory has developed a multihost pathogenesis system based on the P. aeruginosa clinical isolate PA14, in which non-mammalian hosts are used to screen directly for virulence-attenuated mutants. The majority of PA14 mutants isolated using non-mammalian hosts also displayed reduced virulence in a burned mouse model. Surprisingly, only a few host-specific virulence factors were identified, and many of the P. aeruginosa mutants were attenuated in virulence in all the hosts. These studies illustrate the extensive conservation in the virulence mechanisms used by P. aeruginosa to infect evolutionarily diverged hosts, and validate the multihost method of screening for virulence factors relevant to mammalian pathogenesis. Through the use of genetically tractable hosts, the multihost pathogenesis model also provides tools for elucidating host responses and dissecting the fundamental molecular interactions that underlie bacterial pathogenesis.
Insights
Pseudomonas aeruginosa uses conserved virulence mechanisms across diverse hosts. A multihost system effectively screens for bacterial pathogenesis factors relevant to human infections.
Area of Science:
- Microbiology
- Pathogenesis
- Bacterial Virulence
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen infecting various hosts, including humans, plants, and insects.
- Understanding its virulence mechanisms is crucial for combating infections.
- Previous studies have identified some host-specific virulence factors.
Purpose of the Study:
- To develop and validate a multihost pathogenesis system for screening Pseudomonas aeruginosa virulence mutants.
- To identify conserved and host-specific virulence factors.
- To explore the utility of non-mammalian hosts for studying mammalian pathogenesis.
Main Methods:
- Utilized the clinical isolate Pseudomonas aeruginosa PA14.
- Developed a multihost pathogenesis system employing non-mammalian hosts (plants, nematodes, insects).
- Screened for virulence-attenuated mutants using these hosts.
- Validated findings in a burned mouse model.
Main Results:
- The majority of mutants attenuated in non-mammalian hosts also showed reduced virulence in the mouse model.
- Few host-specific virulence factors were identified.
- Many Pseudomonas aeruginosa mutants exhibited broad-spectrum virulence attenuation across all tested hosts.
Conclusions:
- Bacterial pathogenesis mechanisms are highly conserved across evolutionarily divergent hosts.
- The multihost screening method is effective for identifying virulence factors relevant to mammalian pathogenesis.
- This model system aids in dissecting host-pathogen interactions and host responses.