The viruses are inoculated to a specimen. After specific contact time (2 hr as a standard time but can be varied up to 24 hr), the remaining infectious virus is counted and the reduction rate is calculated by the comparison between the antiviral product test specimen and the reference specimen. The quantification of virus infection titre is performed by plaque assay or TCID50 method.
Examples of viruses used are Influenza A virus (H3N2, H1N1,229E ,Etc.) and Feline calicivirus, however other species of virus are available on request.