Plaque Reduction Assay

Plaque-based assay is a standard method used to determine virus concentration in terms of infectious dose. Viral plaque assays determine the number of plaque forming units (pfu) in a virus sample, which is one measure of virus quantity.

This assay is used to evaluate the virucidal efficacy of liquid, aerosol, trigger-spray microbicides intended for use on inanimate, nonporous environmental surfaces, treated surfaces and textiles, and Chemical, natural, and synthetic compounds. This practice may be employed with most viruses, which can be grown in cultured cells.

Methodology

• A confluent monolayer of host cells is infected with the virus and the infected cell area will create a plaque (an area of infection surrounded by uninfected cells) which can be seen with an optical microscope.
• In this rapid test, the test compound is added only in two different concentrations to infected cells, and the number of formed plaques is counted and compared to controls (untreated infected cells).
• Finally, percentage reduction in plaques formation in comparison to control is recorded.

• Results are presented as inhibition percentage of the used test compound