ESTABLISHING ACTIVE LYSOGENY, A BACTERIAL-PHAGE INTERACTION THAT SUPPORTS COOPERATION

The human bacterial pathogen Listeria monocytogenes harbors a prophage within its genome, which is known to reproduce by both lytic and lysogenic cycles. We have previously shown that this prophage adopts an unusual behavior when L. monocytogenes infects mammalian cells. During macrophage cells infection the prophage, which is inserted within comK gene, excises its genome leaving an intact comK gene that is necessary to facilitate bacterial phagosomal escape. Even though, phage excision occurs, it does not lead to generation of progeny virions and bacterial lysis, suggesting that the prophage cooperates with it host to promote successful mammalian cells infection. We termed this novel phage behavior active lysogeny, as the prophage is highly active transcriptionally and genomically yet preserves the lysogenic mode. Transcriptome analysis has demonstrated a distinct phage transcription profile under each life cycle (lysogenic, lytic and active lysogeny) insinuating a specific regulatory mechanism for each mode. Multiple studies in the lab indicate that both bacterial and phage factors are involved in maintaining active lysogeny, which will be describe.