The discoverer of phage, Felix d'Herelle , refused to believe in the existence of a phage carrier state, whereas his key opponent, Jules Bordet , insisted taht at least some viruses lacked virulent characteristics. The implications of research on lysogeny for gene regulation, cancer, and animal virology are widespread and extremely important. Bacteriophage lambda has a dsDNA genome of 48,502 bp. In the capsid, the chromosome is a linear dsDNA molecule with 12 nt ssDNA cohesive termini. The linear dsDNA circularizes as a result of annealing between the complementary 3' overhanging cos sites.
Subsequent events depend on whether lytic or lysogenic growth occurs.
If lytic growth occurs, DNA replication then occurs followed by synthesis of the capsid proteins to package the newly-replicated phage. In this form of replication, the product of the O gene binds to four 19 bp palindromes at the origin of replication. Subsequently, the product of the P gene, along with the host cell DnaB protein binds to the origin to establish a replisome . Late replication of bacteriophage lambda is designed to produce many copies of the genome in a form suitable for packaging into new phage capsids. How the phage switches from one form of replication to another is not known.