A viral plaque is a visible structure formed after introducing a viral sample to a
cell culture
Cell culture or tissue culture is the process by which cells are grown under controlled conditions, generally outside of their natural environment. The term "tissue culture" was coined by American pathologist Montrose Thomas Burrows. This te ...
grown on some
nutrient medium
A growth medium or culture medium is a solid, liquid, or semi-solid designed to support the growth of a population of microorganisms or cells via the process of cell proliferation or small plants like the moss ''Physcomitrella patens''. Differe ...
. The
virus
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea.
Since Dmitri Ivanovsky's 1 ...
will replicate and spread, generating regions of cell destruction known as plaques. For example,
Vero cell
Vero cells are a lineage of cells used in cell cultures. The 'Vero' lineage was isolated from kidney epithelial cells extracted from an African green monkey (''Chlorocebus'' sp.; formerly called ''Cercopithecus aethiops'', this group of monkeys ha ...
or other tissue cultures may be used to investigate an
influenza virus
''Orthomyxoviridae'' (from Greek ὀρθός, ''orthós'' 'straight' + μύξα, ''mýxa'' 'mucus') is a family of negative-sense RNA viruses. It includes seven genera: ''Alphainfluenzavirus'', ''Betainfluenzavirus'', '' Gammainfluenzavirus'', ' ...
or
coronavirus
Coronaviruses are a group of related RNA viruses that cause diseases in mammals and birds. In humans and birds, they cause respiratory tract infections that can range from mild to lethal. Mild illnesses in humans include some cases of the com ...
, while various
bacterial cultures would be used for
bacteriophages.
Counting the number of plaques can be used as a method of
virus quantification
Virus quantification involves counting the number of viruses in a specific volume to determine the virus concentration. It is used in both research and development (R&D) in commercial and academic laboratories as well as production situations whe ...
. These plaques can sometimes be detected visually using
colony counter
In microbiology, colony-forming unit (CFU, cfu or Cfu) is a unit which estimates the number of microbial cells (bacteria, fungi, viruses etc.) in a sample that are viable, able to multiply via binary fission under the controlled conditions. Cou ...
s, in much the same way as bacterial colonies are counted; however, they are not always visible to the naked eye, and sometimes can only be seen through a
microscope
A microscope () is a laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisibl ...
, or using techniques such as staining (e.g. neutral red for eukaryotes
or
giemsa
Giemsa stain (), named after German chemist and bacteriologist Gustav Giemsa, is a nucleic acid stain used in cytogenetics and for the histopathological diagnosis of malaria and other parasites.
Uses
It is specific for the phosphate groups of ...
for bacteria
) or
immunofluorescence. Special computer systems have been designed with the ability to scan samples in batches.
The appearance of the plaque depends on the host strain, virus and the conditions. Highly virulent or
lytic
The lytic cycle ( ) is one of the two cycles of viral reproduction (referring to bacterial viruses or bacteriophages), the other being the lysogenic cycle. The lytic cycle results in the destruction of the infected cell and its membrane. Bacter ...
strains create plaques that look clear (due to total cell destruction), while strains that only kill a fraction of their hosts (due to partial resistance/lysogeny), or only reduce the rate of cell growth, give turbid plaques. Some partially lysogenic phages give bull's-eye plaques with spots or rings of growth in the middle of clear regions of complete lysis.
See also
*
Assay
*
Viral culture
Viral culture is a laboratory technique in which samples of a virus are placed to different cell lines which the virus being tested for its ability to infect. If the cells show changes, known as cytopathic effects, then the culture is positive.
...
*
Virus
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea.
Since Dmitri Ivanovsky's 1 ...
*
Virus quantification
Virus quantification involves counting the number of viruses in a specific volume to determine the virus concentration. It is used in both research and development (R&D) in commercial and academic laboratories as well as production situations whe ...
*
Virology
Virology is the Scientific method, scientific study of biological viruses. It is a subfield of microbiology that focuses on their detection, structure, classification and evolution, their methods of infection and exploitation of host (biology), ...
References
External links
* An image o
Bacteriophage plaques in agar
{{DEFAULTSORT:Viral Plaque
Virology
Bacteriophages