Fig. 5.

Surface detection is a host-nonspecific signal that activates virulence. (A) Schematic of proposed model in which bacterial cells detect host surfaces through mechanical cues during initial attachment. The induction of virulence through this detection mechanism establishes an environment that is suitable for bacterial colonization of the host. (B) An ‘AND’ gate model for surface-activated virulence in which both surface sensing (mediated by PilY1) and quorum sensing (mediated by LasR) are required for activating virulence.