Modelling the Onset of Virulence in Pathogenic Bacteria

Bacterial virulence is a multifactorial process. In this chapter, we review some known mechanisms used by bacteria to trigger their production of virulence factors. We develop the idea that although the onset of virulence shows up an abrupt transition, the modelling of this dynamics can be classified in two qualitatively distinct infectious transitions which are respectively called “shift” or “switch.” We review methods enabling one to determine the types of behaviour that can be exhibited by a given model and we consider applications in three cases of virulence factor regulation. We conclude that in most cases a “successful” infection would require that the onset of virulence follows an irreversible switch behaviour.