TCID50

This chapter focuses on TCID50.The TCID50 assay measures infectious cytocidal virions. The host cells are grown in confluent monolayers to which various dilutions of the virus are added. The virus replicates and the progeny virus that is released into the supernatant fluid is free to infect any other cell. The cytopathological damage is allowed to develop usually over a period of days. The TCID50 is defined as the dilution of virus required to infect 50% of the cell cultures inoculated. It is a quantal assay of viral infectivity in that each infected well yields only one piece of information, namely, is there CPE or not? The TCID 50 titer does not tell how many infectious units may be present in a given sample, but only that this dose or dilution will produce CPE in 50% of the cell cultures inoculated.