A bacterial cell harbouring the genome of a bacteriophage integrated into the bacterial cell's chromosomal DNA. Lysogens are latent forms of bacteriophages. A lysogenized phage genome is often referred to as a prophage. Prophages sometimes encode genes for toxins that are expressed by their bacterial host cell. Examples include diphtheria toxin, scarlet fever toxin, Staphylococcus aureus Panton-Valentine leukocidin, and enterotoxin A.