Plaque Forming Unit

**Semantic type:** Quantitative Concept

**Definition:** A measure of viable infectious entities (e.g. viral particles or group of particles) in the specimen or product defined as the smallest quantity that can produce a cytopathic effect in the host cell culture challenged with the defined inoculum, visible under the microscope and/or to the naked eye as a plaque. A number of plaque forming units (PFU) per unit volume is a conventional way to refer the titer of an infective entity in a specimen or preparation.

**Synonyms:** - PFU - PFU - PFU - PLAQUE-FORMING UNITS - PLAQUE-FORMING UNITS - PLAQUE-FORMING UNITS - [PFU] - [PFU] - [PFU] - [PFU] - [PFU] - plaque forming unit - plaque forming units - {PFU} - {PFU}