Explanation

Prophage is the DNA of a bacteriophage that is repressed for lytic functions and that is maintained in the host bacterium in a stable state. The phage genome may be integrated into the DNA of its bacterial host and may be replicated along with the host DNA, as is the case for bacteriophage lambda or may be maintained as extrachromoromal-DNA, as in the case for bacteriophage $P_{1}$.