A VIRUS which invades a bacterium (see BACTERIA). Containing either single-stranded or double-stranded DNA or RNA, a particular phage generally may infect one or a limited number of bacterial strains or species. After infection, once phage nucleic acid has entered the host cell, a cycle may result whereby the bacteria are programmed to produce viral components, which are assembled into virus particles and released on bacterial lysis (disintegration). Other (temperate) phages induce a non-lytic, or lysogenic, state, in which phage nucleic acid integrates stably into and replicates with the bacterial chromosome. The relationship can revert to a lytic cycle and production of new phages. In the process the phage may carry small amounts of donor bacterial DNA to a new host: the production of diphtheria toxin by Corynebacterium diphtheriae and of erythrogenic toxin by Streptococcus pyogenes are well-known examples of this e?ect.... bacteriophage
n. an interaction between a *bacteriophage and its host in which a latent form of the phage (prophage) exists within the bacterial cell, which is not destroyed. Under certain conditions (e.g. irradiation of the bacterium) the phage can develop into an active form, which reproduces itself and eventually destroys the bacterial cell.... lysogeny
n. the transfer of DNA from one bacterium to another by means of a *bacteriophage (phage). Some bacterial DNA is incorporated into the phage. When the host bacterium is destroyed the phage infects another bacterium and introduces the DNA from its previous host, which may become incorporated into the new host’s DNA.... transduction
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