Latent viruses are those viruses that can incorporate their genetic material into the genetic material of the infected host cell. Because the viral genetic material can then be replicated along with the host material, the virus becomes effectively "silent" with respect to detection by the host. Latent viruses usually contain the information necessary to reverse the latent state. The viral genetic material can leave the host genome to begin the manufacture of new virus particles.

The molecular process by which a virus becomes latent has been explored most fully in the bacteriophage designated lambda. The lysogenic process is complex and involves the interplay between several proteins that influence the transcription of genes that either maintain the latent state or begin the so-called lytic process, where the manufacture of new virus begins.

Bacteriophage lambda is not associated with disease. However, other viruses that...