Expert: Florence M Rollwagen - 4/22/2009

Question
On the molecular level, how do viruses control replication in latency? How do they maintain being in the latent state?

Answer
Hi Brett:  Thanks for your question.  This is a very lengthy and complex subject which can't be fully addressed in this format.  I'll give you an outline and some sources.

Viral latency is the ability of viruses to lie dormant in the host without causing infection.

There are several different mechanisms, depending on which virus we're talking about.

Herpesviruses use episomal latency, in which the viral genome lies naked in the cytoplasm.  This is susceptible to the action of ribozymes, but is otherwise quite effective.   Shingles occurrence very many years after chickenpox infection is an example.  http://en.wikipedia.org/wiki/Virus_latency

Other viruses, such as the retroviruses establish latency by integrating the viral genome into the host genome.  HIV is an example of this one.

Latency associated transcripts (LAT) are found in viral genomes.  These serve to inhibit the host normal metabolic activities (including apoptosis) and regulates the viral genome:
http://en.wikipedia.org/wiki/HHV_Latency_Associated_Transcript

Here is a more thorough review for human papilloma virus: http://cme.medscape.com/viewarticle/440152

Here's another one for herpes:  http://www.virology.ws/2009/04/03/how-herpes-simplex-virus-exits-latency/

Hope this helps.  Write back if you have more questions.

FM Rollwagen, PhD