Definition web:
  Viral Plaque Assays

In viral plaque assays, visible structures are formed in a cell culture contained within some nutrient medium (such as agar). By propagating within the cell cultures, the viruses generate zones of cell destruction known as plaques. These plaques can be detected visually—sometimes with the naked eye, and sometimes through other techniques such as staining, microscopy, hemadsorption or immunofluorescence, to name a few. By detecting and evaluating these plaques, a researcher can gauge virus activity and effectiveness, as well as enumerate effective viruses.

(See Biology of Microorganisms, 8th Edition, M. T. Madigan, J. M. Martinko and J. Parker, © 1997, Prentice Hall, pp 255-257; Principles of Microbiology and Immunology, Bernard D. Davis et al., © 1968, Harper and Row, Publishers, pp.660-661.)

In viral plaque assays, the plaques formed are enumerated, either manually or using automated image analysis techniques.

See also: Assays