LYSOGENY

type of life cycle that takes place in a bacteriophage following its infection of certain types of bacteria. In this cycle, the genome (the collection of genes in the nucleic-acid core of a virus) of the bacteriophage stably integrates into the chromosome of the host bacterium and replicates in concert with it. No progeny viruses are produced in the process. Instead, the infecting virus lies dormant within the bacterium's chromosome until the bacterium is exposed to certain stimuli, such as ultraviolet light. Following this induction event, the virus enters a life cycle in which its genome is excised from the host chromosome and begins to multiply, forming new progeny viruses. Ultimately the bacterial host is destroyed (lysed) and the virus particles are released into the environment and infect new bacterial cells. This process was first explained by the French biologist Andr Lwoff in the early 1950s.