title: Evolution of virulence in emerging epidemics.
abstract: Theory predicts that selection for pathogen virulence and horizontal transmission is highest at the onset of an epidemic but decreases thereafter, as the epidemic depletes the pool of susceptible hosts. We tested this prediction by tracking the competition between the latent bacteriophage λ and its virulent mutant λcI857 throughout experimental epidemics taking place in continuous cultures of Escherichia coli. As expected, the virulent λcI857 is strongly favored in the early stage of the epidemic, but loses competition with the latent virus as prevalence increases. We show that the observed transient selection for virulence and horizontal transmission can be fully explained within the framework of evolutionary epidemiology theory. This experimental validation of our predictions is a key step towards a predictive theory for the evolution of virulence in emerging infectious diseases.
authors.affiliation: Centre d'Ecologie Fonctionnelle et Evolutive (CEFE) - UMR 5175, Montpellier, France. berngruber@gmail.com
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Berngruber
authors.forename: Rémy
authors.initials: R
authors.lastname: Froissart
authors.forename: Marc
authors.initials: M
authors.lastname: Choisy
authors.forename: Sylvain
authors.initials: S
authors.lastname: Gandon
mesh_terms: D010582:Bacteriophage lambda / Q000472:pathogenicity*; D005075:Biological Evolution; D021821:Communicable Diseases, Emerging / Q000453:epidemiology / Q000635:transmission* / Q000821:virology; D018562:Disease Transmission, Infectious; D058872:Epidemics; D004926:Escherichia coli / Q000821:virology*; D005434:Flow Cytometry; D054884:Host-Pathogen Interactions; D008954:Models, Biological; D009154:Mutation; D014774:Virulence