A programme for the construction of a lambda phage.

Infection of a sensitive host by the lambdoid coliphages can cause death of the bacterial cell by lysis or can lead to a lysogenic cell, with the viral DNA stably integrated into the host chromosome. These alternative responses both require the coordination of several host and phage functions, and lambda infection follows a well controlled developmental plan. The lytic and lysogenic pathways of lambdoid infection are reviewed, with emphasis on the variety of control mechanisms involved in the commitment to a particular pathway.