Plenary Lecture: HIV dynamics and Load: Implications for Therapy and Eradication
April 11, 1997
Dr. John Mellors, et al
This plenary presentation gave a good overview of HIV replication during the asymptomatic phase of the infection. Although there are only low levels of infectious HIV, virus is being made and removed very rapidly. An analogy would be a rushing stream, only a small amount of water at any one point but a lot of water passing by. This rapid virus production throughout the asymptomatic phase of HIV has two major implications.
For the technically minded: about 1010 virions are produced each day; free virion half-life, 0.19 day; infected lymphocyte, half life 2.2 days; generation time, 2.5 days to give about 140 generations of virus replications per year; 109 to 1010replication cycles per day; mutation rate, 3x10-5/bp per cycle.
These factors lead to the conclusion that antiviral therapies, that give only partial control of HIV replication, are doomed to eventual failure. Each 10-fold (log) reduction in viral load has been estimated to lower the risk of clinical progression by 65%. Therefore, therapy should aim aggressively for a complete stop in replication:
Virus load as a prognostic factor.Higher virus load is correlated with:
However, CD4 cell count is an independent prognostic factor. J Cuffin (XI International Conference on AIDS, Vancouver, 1996) suggested an analogy, a train heading for rocks on the track. The speed of the train represents the viral load, the distance from the rocks represents the CD4 cell count. The lower the speed (viral load) and the greater the distance (CD4cell count) the better the prognosis.
Cure?Complete eradication of HIV unlikely, but avoiding progression to AIDS for prolonged time with continuous therapy is becoming a real possibility.
This article was provided by TheBodyPRO.com. It is a part of the publication The 10th Annual International Society For Antiviral Research Conference.