There are three types of persistent infections, latent, chronic and slow, in which the virus stays inside the host cell for prolonged periods of time.  During latent infections there is minimal to no expression of infected viral genome. The genome remains within the host cell until the virus is ready for replication.  Chronic infections have similar cellular effects as acute cytocidal infections but there is a limited number of progeny and viruses involved in transformation.  Lastly, slow infections have a longer incubation period in which no physiological, morphological or subcellular changes may be involved.