Important note: Information in this article was accurate in 1999. The state of the art may have changed since the publication date.

Thursday May 27 2:17 AM ET

A team led by Linqi Zhang of Rockefeller University reported in Thursday's New England Journal of Medicine that the number of white blood cells that harbor HIV may decline over time. However, they estimated, it will take "roughly seven to 10 years of continuous, truly effective therapy ... to eliminate this reservoir" and actually cure a patient.

Because it is difficult to maintain treatment for that long, they said, doctors must find a better way to kill off the cells that silently harbor the virus. In a more pessimistic study, published in the same issue of the Journal, a group led by Manohar R. Furtado of Northwestern University Medical School in Chicago concluded that HIV lingers in cells for so long, it appears that the virus "cannot be eradicated (at all) with current treatments."

As older infected cells die off, they said, human immunodeficiency virus may be infecting new white blood cells. The result would be a continuously-replenished supply of cells capable of reactivating AIDS once a patient stops taking his medicine.

"Unless this quasi-steady state eventually disappears with longer periods of therapy or can be overcome by the use of more potent therapies or alternative approaches that block the potential spread of virus within tissues," they said, "HIV-1 may never be eradicated."

A study published earlier this year in Nature Medicine estimated that it would take 60 years of treatment to eliminate the virus.

"These findings are not unexpected," Dr Anthony Fauci, director of the National institute of Allergies and Infectious Diseases (NIAID), which helped fund both studies, said in a statement.

"What all these studies underscore is the pressing need to develop more effective, less toxic medications that can be used over the long term to suppress HIV, as well as novel strategies to then purge residual virus from the body and boost the immune system," he added.

New AIDS drugs are able to remove much of the HIV virus from the body. But researchers have long known that many copies of the virus lurk in white blood cells, ready to reactivate the deadly infection.

The new research is an attempt to assess how long it would take for all the infected white blood cells to die off naturally. Generally, about half the infected cells die every six months.

But because only one surviving cell is needed to initiate a new infection, it can take a long time for the body to rid itself of cells that harbor HIV. And if infected cells are able to pass on the virus to newer cells, even at a slow rate, the risk of AIDS continues.

In an editorial in the Journal, Dr. Roger J. Pomerantz of Thomas Jefferson University in Philadelphia warned that the task of eradicating HIV may be even more complicated if it turns out that the virus can lurk in the eyes, the testicles and the central nervous system. Most AIDS drugs, he said, may not be able to reach those areas.
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Always watch for outdated information. This article first appeared in 1999. This material is designed to support, not replace, the relationship that exists between you and your doctor.

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