Unusual viral infection Unusual virus reactivation 2022-08-14T12:00:00Z Reactivation is the mechanism whereby a latent virus that has infected a host cell switches to a lytic stage, undergoing productive viral replication and allowing the virus to spread. This term refers to reactivation regarded as unusual because of frequency, intensity, location, or nature of the virus, in the sense that the reactivation would not be observed in an immunocompetent host.