HIV-1 Life Cycle Implications For Research

An analysis by two US research groups of HIV-1 infection has shown that far from existing in a dormant state through the "latency period" between infection and the onset of symptoms, the virus is constantly replicating, and is matched only by the replacement of cells by the immune system, according to a report in the journal Nature (January 19).

Using a number of anti-HIV drugs, the researchers were able to induce a rapid reduction in free virus in the plasma within a few days. This reduction is associated with an increase in the number of circulating CD4 T cells. A drawback of the treatment is the rapid appearance of drug-resistant mutations. The researchers note that whether the target is viral polymerase or protease, resistant virus is detectable within a week.

The research groups, extrapolating from changes in the blood of the patients in the study, said that between 108 and 109 virions were being cleared every day, equivalent to 30% of the total. As the level of blood-borne viremia show only gradual changes over many months, the daily rates of viral destruction and production must be comparable. Therefore, say the researchers, a total of 2 x 109 cells per day must have been produced following drug treatment.