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Evolution of virulence in emerging epidemics.
Thomas W Berngruber1, Rémy Froissart, Marc Choisy
1Centre d'Ecologie Fonctionnelle et Evolutive (CEFE) - UMR 5175, Montpellier, France. berngruber@gmail.com
Plos Pathogens
|March 22, 2013
Summary
Virulence and transmission evolve during epidemics. A study on bacteriophages in E. coli showed virulent strains initially dominate but decline as susceptible hosts become scarce, validating evolutionary epidemiology predictions.
Area of Science:
- Evolutionary biology
- Epidemiology
- Microbiology
Background:
- Pathogen virulence and transmission dynamics are key factors in epidemic spread.
- Evolutionary epidemiology theory predicts transient selection for virulence.
Purpose of the Study:
- To experimentally test the prediction that selection for pathogen virulence is highest at epidemic onset.
- To investigate the competition between latent and virulent bacteriophages in a controlled environment.
Main Methods:
- Utilized continuous cultures of Escherichia coli.
- Tracked the competition between latent bacteriophage lambda (λ) and its virulent mutant lambda cI857 (λcI857) during experimental epidemics.
Main Results:
- The virulent mutant λcI857 was strongly favored during the early stages of the epidemic.
- The virulent strain lost competitive advantage as host prevalence increased.
- Observed transient selection for virulence and horizontal transmission.
Conclusions:
- Experimental results align with predictions from evolutionary epidemiology theory.
- Validated theoretical predictions regarding the evolution of virulence during epidemics.
- Provides a foundation for predicting virulence evolution in emerging infectious diseases.
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