Study Finds Patients’ Bodies in Constant Battle With HIV

The immune system of AIDS patients is in a state of all-out war against a relentlessly multiplying virus, according to new research.

In rapid cycles of death and rebirth, the AIDS virus can evolve resistance to new drugs as quickly as a month after a patient begins taking them. The new findings underscore the immense difficulty of developing drugs to keep the infection in check. At the same time, the immune system’s ability to survive years of infection suggests it might retain an unusually strong capacity for regeneration even late in the disease if a way could be found to stop the virus’s reproduction.

Two studies published today in the journal Nature estimate that about half the AIDS virus particles in the bloodstream are killed every two days, only to be replaced by new microbes. The body’s daily casualties amount to about 2 billion virus-fighting lymphocytes, with a similar number of cells recruited and sent into battle to replace them.

This scenario describes the late stage of AIDS, when patients are already quite ill. Whether it is also true in the earlier, seemingly quiescent period of infection is uncertain.

Two research teams, working separately but using similar methods, quantified the production and destruction of the human immunodeficiency virus (HIV) and the immune system cells that are its principal target. The studies are the first precise measurements of day-to-day cellular activity during the long, slow decline in health that characterizes HIV infection.