Prophage

A prophage is a phage (viral) genome inserted and integrated into the circular bacterial DNA chromosome. A prophage, also known as a temperate phage, is any virus in the lysogenic cycle; it is integrated into the host chromosome or exists as an extrachromosomal plasmid. Technically, a virus may be called a prophage only while the viral DNA remains incorporated in the host DNA. This is a latent form of a bacteriophage, in which the viral genes are incorporated into the bacterial chromosome without causing disruption of the bacterial cell.