Lysogen

A lysogen or lysogenic phage is a phage that can exist as a DNA in its dormant state (prophage) within its host organism. A prophage is either integrated into the host bacteria's chromosome or more rarely exists as a stable plasmid within the host cell. The prophage expresses gene(s) that repress the phage's lytic action, until this suppression is disrupted (see lytic cycle). Currently a variety of studies are being conducted to see whether other genes are active during lysogeny, examples of which include phage-encoded tRNA and virulence genes.