Lysogenic conversion is when a temperate phage induces a change in the phenotype of the bacteria infected that is not part of a usual phage cycle. Changes can often involve the external membrane of the cell by making it impervious to other phages or even by increasing the pathogenic capability of the bacteria for a host.
As an example, Corynebacterium diphtheriae produces the toxin of diphtheria only when it is infected by the phage β. In this case, the gene that codes for the toxin is carried by the phage, not the bacteria.
Lysogeny, or the lysogenic cycle, is one of two methods of viral reproduction (the lytic cycle is the other).
An example of a virus that enters the lysogenic cycle is herpes, which first enters the lytic cycle after infecting a human, then the lysogenic cycle before travelling to the nervous system where it resides in the nerve fibers as an episomal element.
In some interactions between lysogenicphages and bacteria, lysogenicconversion may occur.
The lysogenicities of the strains, the sensitivities of the strains to the phages and the sensitivities of the phage-resistant mutants to phages were studied to clarify the specificities of the phages.
Conversion was accomplished by a positive conversion effector, which was a phage characteristic expressed by the prophage and vegetatively reproducing phage.
Lysogenization with phage 188 of phage-sensitive strains conferred on the lysogenized cells the ability to acquire chromosome and plasmid resistance markers.
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