What is "lysogen"

n. (context biology English) A phage that can exist as a prophage within its host organism.

A lysogen or lysogenic bacterium is a bacterial cell in which a phage exists as DNA in its dormant state ( prophage). 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 repression 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.