Like PRNT assays, neutralization assays test the ability of a compound to neutralize live virus. However, unlike PRNT assays they aren’t limited to viruses that cause plaques. These assays are typically performed in a 96-well or 384-well plates (microneutralization assay) and are generally less labor intensive that PRNT. To perform these assays, a monolayer of permissive cells are seeded in microwell plates overnight before infecting them with virus in the presence of absence of a test compound such as a small molecule or antibody. The wells treated with the compound are then compared to the wells without treatment, and well treated with a positive or negative control. The concentration of compound that reduced the virus by 50% is denoted IC50 or EC50.