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 recently shown that this
prophage adopted 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 during this special
lysogenic mode.
The objective of this work is to better understand the bacterial – prophage interactions and to decipher the regulatory model of the active lysogenic cycle. Characterization of the three life cycles of the prophage: lytic, lysogenic and an active lysogenic is currently performed and is expected to reveal factors that control the phage during L. monocytogenes infection of mammalian cells.
Here we present preliminary experiments characterizing the prophage excision rate, plaque formation and transcription profile of its genes under lysogenic and lytic states. These experiments are the basis for future genome wide RNA-seq analysis of the phage and the bacteria under the different conditions.
