In virology, superinfection is the process by which a cell that has previously been infected by one virus gets co-infected with a different strain of the virus, or another virus, at a later point in time. 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 HIV 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.
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, such as Clostridium difficile overgrowth post antibiotic treatment.
Superinfection immunity in Lambda phages
When a cell is undergoing the lysogenic cycle and infected with a lambda phage (making it a lambda lysogen), other lambda phages that infect it are not able to undergo lytic development and produce progeny. The incoming phage can inject its DNA into the cell, but the DNA is immediately repressed and no transcription of genes or translation of phage proteins initiates. Therefore, lambda lysogens are immune to infection by other lambda phage particles. This occurs because the lambda lysogen is continuously producing cI repressor proteins to the point where the amount of cI proteins in the cell exceeds the amount needed to inhibit the replication of more than one phage. These repressor proteins bind to the superinfecting phage DNA operators to block transcription of the phage's genes by the cell and viral polymerase enzymes.
|This article about a disease, disorder, or medical condition is a stub. You can help Wikipedia by expanding it.|