pfu calculation
One of the most important procedures in virology is to measure the virus titer – the concentration of viruses in a sample. A widely used method for determining the quantity of infectious virus is the plaque assay. This technique was first used to calculate the titers of bacteriophage stocks. Renato Dulbecco modified this procedure for use in animal virology in 1952, and it has since been used for reliable determination of the titers of a number of different viruses.