Regulation of cohabiting phage-elements in Listeria monocytogenes

Most bacterial pathogens are lysogens, namely carry DNA of phages within their genome, which referred to as prophages. While these prophages have the potential to turn under stress into infective viruses that kill their host in a matter of minutes, it remains unclear how pathogens manage to survive this internal threat under the stresses imposed in the mammalian niche. Several years ago, we uncovered a dynamic pathogen-phage interaction, in which an infective prophage promotes the virulence of its host, the bacterial pathogen Listeria monocytogenes (Lm), via an unusual adaptive behaviour, termed active lysogeny. More recently, we discovered that the prophage, though fully infective, is non-autonomous, completely dependent on regulatory factors derived from another inactive phage-element that reside within the Lm chromosome. These findings lead us to expose an intimate cross-regulatory network between the two cohabiting phage elements, that promotes bacteria-phage cooperation in the mammalian environment. In this talk I will present our recent published and unpublished data.