Lysogenic cycle

) can release it, causing proliferation of new phages via the lytic cycle. Lysogenic cycles can also occur in eukaryotes, although the method of incorporation of DNA is not fully understood.

Mixed cycles

Following are some types of viruses that replicate by the lysogenic cycle, but also partly by the lytic cycle.

Bacteriophages

Some DNA phages, called temperate phages, only lyse a small fraction of bacterial cells; in the remaining majority of the bacteria, the phage DNA becomes integrated into the bacterial chromosome and replicates along with it. In this lysogenic state, the information contained in the viral nucleic acid is not expressed. The model organism for studying lysogeny is the lambda phage. Roughly 50-60 nucleotides are taken out of the lysogenic pathway and used.

Lysogenic conversion

In some interactions between lysogenic phages and bacteria, lysogenic conversion may occur. It 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.

Examples:
* "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.
* "Vibrio cholerae" is a non-toxic strain that can become toxic, producing cholera toxin, when it is infected with the phage CTXφ.
* "Clostridium botulinum" causes botulism.
* "Streptococcus pyogenes" causes scarlet fever.
* Shiga toxin
* Tetanus

References

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lysogenic cycle — noun A form of viral reproduction involving the fusion of the nucleic acid of a bacteriophage with that of a host, followed by proliferation of the resulting prophage See Also: lytic cycle … Wiktionary
lytic cycle — noun The normal process of viral reproduction involving penetration of the cell membrane, nucleic acid synthesis and lysis of the host cell See Also: lysogenic cycle … Wiktionary
Bacteriophage — This article is about a biological infectious particle; for other uses, see phage (disambiguation). A bacteriophage (from bacteria and Greek φάγειν phagein to eat ) is any one of a number of viruses that infect bacteria. The term is commonly used … Wikipedia
Transduction (genetics) — Transduction Transduction is the process by which DNA is transferred from one bacterium to another by a virus.[1] It also refers to the process whereby foreign DNA is introduced into another cell via a viral vector. Trans … Wikipedia
lysogeny — The phenomenon by which a bacterium is infected by a temperate bacteriophage whose DNA is integrated into the bacterial genome and replicates along with the bacterial DNA but remains latent or unexpressed; triggering of the lytic cycle may occur… … Medical dictionary
Lysogen — A lysogen or lysogenic phage is a phage that can exist as a prophage within its host organism. A prophage is the phage DNA in its dormant state, and is either integrated into the host bacteria s chromosome or more rarely exists as a stable… … Wikipedia
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