title: What is a pathogen? Toward a process view of host-parasite interactions.
abstract: Until quite recently and since the late 19(th) century, medical microbiology has been based on the assumption that some micro-organisms are pathogens and others are not. This binary view is now strongly criticized and is even becoming untenable. We first provide a historical overview of the changing nature of host-parasite interactions, in which we argue that large-scale sequencing not only shows that identifying the roots of pathogenesis is much more complicated than previously thought, but also forces us to reconsider what a pathogen is. To address the challenge of defining a pathogen in post-genomic science, we present and discuss recent results that embrace the microbial genetic diversity (both within- and between-host) and underline the relevance of microbial ecology and evolution. By analyzing and extending earlier work on the concept of pathogen, we propose pathogenicity (or virulence) should be viewed as a dynamical feature of an interaction between a host and microbes.
authors.affiliation: a Université Laval ; Québec , Canada.
authors.forename: Pierre-Olivier
authors.initials: PO
authors.lastname: Méthot
authors.forename: Samuel
authors.initials: S
authors.lastname: Alizon
mesh_terms: D000818:Animals; D001419:Bacteria / Q000472:pathogenicity; D005075:Biological Evolution; D005658:Fungi / Q000472:pathogenicity; D014644:Genetic Variation; D006790:Host-Parasite Interactions; D054884:Host-Pathogen Interactions; D006801:Humans; D014774:Virulence / Q000235:genetics*; D014780:Viruses / Q000472:pathogenicity
keywords: disease; ecology; evolution; infection; process; virulence