View source for Biology:Viral plaque

{{Short description|Visible structure formed by virus propagation within a cell culture}}
[[File:M. smegmatis plaque.jpg|thumb|Plaques from a virus isolated from a compost heap near UCLA. The bacterium is ''M. smegmatis.'']]

A '''viral plaque''' is a visible structure formed after introducing a viral sample to a [[Biology:Cell culture|cell culture]] grown on some [[Biology:Substrate|nutrient medium]]. The [[Biology:Virus|virus]] will replicate and spread, generating regions of cell destruction known as '''plaques'''. For example, [[Biology:Vero cell|Vero cell]] or other tissue cultures may be used to investigate an influenza virus or [[Biology:Coronavirus|coronavirus]], while various [[Biology:Microbiological culture|bacterial cultures]] would be used for bacteriophages.<ref>{{Citation |last=Abedon |first=Stephen T. |title=Detection of Bacteriophages: Phage Plaques |date=2018 |url=https://doi.org/10.1007/978-3-319-40598-8_16-1 |work=Bacteriophages: Biology, Technology, Therapy |pages=1–32 |editor-last=Harper |editor-first=David R. |access-date=2023-12-02 |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-319-40598-8_16-1 |isbn=978-3-319-40598-8 |s2cid=89660218 |editor2-last=Abedon |editor2-first=Stephen T. |editor3-last=Burrowes |editor3-first=Benjamin H. |editor4-last=McConville |editor4-first=Malcolm L.}}</ref><ref>{{cite journal |last1=Youil |first1=R |last2=Su |first2=Q |last3=Toner |first3=T. J |last4=Szymkowiak |first4=C |last5=Kwan |first5=W-S |last6=Rubin |first6=B |last7=Petrukhin |first7=L |last8=Kiseleva |first8=I |last9=Shaw |first9=A. R |last10=DiStefano |first10=D |date=2004-09-01 |title=Comparative study of influenza virus replication in Vero and MDCK cell lines |url=https://www.sciencedirect.com/science/article/pii/S0166093404001016 |journal=Journal of Virological Methods |volume=120 |issue=1 |pages=23–31 |doi=10.1016/j.jviromet.2004.03.011 |pmid=15234806 |issn=0166-0934}}</ref>

Counting the number of plaques can be used as a method of [[Virus quantification|virus quantification]]. These plaques can sometimes be detected visually using colony counters, 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 [[Engineering:Microscope|microscope]], or using techniques such as staining (e.g. neutral red for eukaryotes<ref>{{cite journal| doi = 10.1099/0022-1317-5-3-419| issn = 0022-1317| volume = 5| issue = 3| pages = 419–427| last = Finter| first = N. B| title = Dye Uptake Methods for Assessing Viral Cytopathogenicity and Their Application to Interferon Assays| journal = Journal of General Virology| access-date = 2012-03-26| date = 1969-10-01| url = http://vir.sgmjournals.org/content/5/3/419| doi-access = free}}</ref> or giemsa for bacteria<ref name="Marvin1969">{{cite journal
| last1 = Marvin | first1 = D. A.
| last2 = Hohn | first2 = B.
| title = Filamentous bacterial viruses
| journal = Bacteriological Reviews
| volume = 33
| issue = 2
| pages = 172–209
| year = 1969
| doi = 10.1128/br.33.2.172-209.1969
| pmid = 4979697
| pmc = 378320
}}</ref>)  or [[Biology:Immunofluorescence|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 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.<ref>{{cite journal |last1=Ramesh |first1=Nachimuthu |last2=Archana |first2=Loganathan |last3=Madurantakam Royam |first3=Madhav |last4=Manohar |first4=Prasanth |last5=Eniyan |first5=Kandasamy |date=2019-06-17 |title=Effect of various bacteriological media on the plaque morphology of Staphylococcus and Vibrio phages |journal=Access Microbiology |volume=1 |issue=4 |pages=e000036 |doi=10.1099/acmi.0.000036 |doi-access=free |issn=2516-8290 |pmc=7470289 |pmid=32974524}}</ref>

==See also==
* [[Biology:Assay|Assay]]
* [[Biology:Viral culture|Viral culture]]
* [[Biology:Virus|Virus]]
* [[Virus quantification]]
* [[Biology:Virology|Virology]]

==References==
{{reflist}}

==External links==
* An image of [http://www.microbiologybytes.com/video/Bacteriophages.html Bacteriophage plaques in agar]

{{DEFAULTSORT:Viral Plaque}}
[[Category:Virology]]

{{Sourceattribution|Viral plaque}}