superinfection

In virology, superinfection is the process by which a cell, that has previously been infected by one virus, gets coinfected with a different strain of the virus, or another virus at a later point in time.^[1] Viral superinfections of serious conditions can lead to resistant strains of the virus, which may prompt a change of treatment. For example, an individual superinfected with two separate strains of the HIV virus may contract a strain that is resistant to antiretroviral treatment. The combined infection has also been shown to reduce the overall effectiveness of the immune response.^[2]

In medicine, superinfection is an infection following a previous infection, especially when caused by microorganisms that are resistant or have become resistant to the antibiotics used earlier.

Superinfection, according to Dorland's illustrated medical dictionary, is a condition produced by sudden growth of a type of bacteria, different from the original offenders in a wound or lesion under treatment.

Superinfection in Lambda phage

When a cell is a lambda lysogen, another lambda phage that infects is not able to undergo lytic development and produce phage. The incoming phage can inject DNA, but the DNA is immediately shut down and no transcription/translation of the lambda initiates. Therefore, lambda lysogens are immune to infection by another lambda phage particle. The reason is that the lysogen is continuously producing cI repressor. The amount of cI protein exceeds the amount needed to shut down more than one phage. The extra repressor binds to the superinfecting phage DNA and prevents its transcription.

References

1. ^ http://www.avert.org/hivtypes.htm
2. ^ http://www.caps.ucsf.edu/pubs/FS/revsuperinfection.php

See also

• Coinfection
• Reassortment
• Antibiotic resistance
• HIV superinfection

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