CO-REGULATION OF INFECTIVE AND DEFECTIVE PROPHAGES PROMOTES LISTERIA MONOCYTOGENES VIRULENCE

Most bacterial pathogens are lysogens, namely carry DNA of phages within their genome, referred to as prophages. While these prophages have the potential to turn under stress into infective viruses which kill their host bacterium in a matter of minutes, it is unclear how pathogens manage to survive this internal threat under the stresses imposed by their invasion into mammalian cells. Several years ago, we uncovered a novel pathogen-phage interaction, in which an infective prophage promotes the virulence of its host, the bacterial pathogen Listeria monocytogenes (Lm), via adaptive behaviour. More recently, we discovered that the prophage, though fully infective, is non-autonomous- completely dependent on regulatory factors derived from inactive prophage remnants that reside within the Lm chromosome. These findings led us to uncover intimate cross-regulatory interactions between different phage elements that promote bacteria-phage cooperative behaviours under mammalian infection. In this talk I will present our recent unpublished data.