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What are the viral particle (VP), plaque formation unit (PFU)?

April 26, 2017FORMATION particle pfu plaque viral VP

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What are the viral particle (VP), plaque formation unit (PFU)?

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Viral particles (VPs) represent the total number of viruses. VPs of purified adenoviruses could be measured by the absorbance at 260 nm. Viruses in DMEM should not be subject to OD260 assay because substances in the growth media interfere with absorption. Since VP includes both live and dead viruses, it does not distinguish the infectious or non-infectious viruses and thus is not a reliable indicator of virus titer. PFU (plaque formation unit) represents the number of infectious viruses because plaque formation assay is a biological assay (see below for details) and measures live viruses. Using PFU as the viral unit will yield more consistent results.