Important note: Information in this article was accurate in 1997. The state of the art may have changed since the publication date.
The Associated Press; 50 Rockefeller Plaza, New York, NY 10020 - Friday, November 14, 1997; 5:25 a.m. EST
Paul Recer, AP Science Writer
The finding, reported today, means that patients may have to take the AIDS drugs for the rest of their lives to hold the virus at bay. It also suggests that new types of treatment will be needed to stamp out the final embers of HIV infection.
Three separate teams of scientists said they found evidence that the human immunodeficiency virus hides in inactive white blood cells in patients who have been taking the drug cocktail for up to three years and seem otherwise virtually free of the virus.
Two papers, by researchers from four different laboratories, are in the journal Science. Another paper, by scientists at the National Institutes of Health, will be published later this month in the Proceedings of the National Academy of Sciences.
Combinations of drugs that block two enzymes used by HIV to reproduce have been enormously effective in stopping the infection. In thousands of patients, HIV in the blood has been reduced to nearly undetectable levels, and CD4 blood cells, the principal target of HIV, have rallied to normal readings.
The success of the drugs raised hopes by some experts that HIV could be eradicated completely from the bodies of patients.
"Although we held out hope that the eradication hypothesis might pan out, I don't think that people really thought it would," said Dr. Joel Gallant of Johns Hopkins University, one of the co-authors of a paper in Science.
He said a prediction that the drug cocktail might effect a cure "was overly optimistic" and based on a mathematical model that is not consistent with what doctors find in the clinics.
Despite the disappointment, Dr. Robert F. Siliciano of Johns Hopkins said that studies did find good news. He said none of the latent viruses studied had developed a resistance to the drug cocktail that has so successfully controlled the infection.
This means, he said, that as long as HIV patients continue to carefully and diligently take the three-drug cocktail, "they have an excellent chance of surviving the infection for a long time without developing symptoms of the disease."
All three of the studies found the latent virus in what are called resting CD4 lymphocytes. These are immune system white blood cells that are primed to defend against antigens from bacteria or from other foreign molecules. Until they encounter antigens that are their specific target, the blood cells are inactive, or resting.
The researchers found that HIV had injected its DNA, or genetic instructions, into the DNA of a small fraction of these resting blood cells.
It is believed that when the resting blood cells were awakened, as by a new infection, then the DNA of the cells would start making new HIV, perhaps sending the virus on a new infective rampage. The researchers conducted laboratory experiments that showed that the latent HIV would start reproducing once the resting blood cells became active.
"Originally, there was hope that these resting cells would decay and after a certain amount of time they would all be gone," said Dr. Joseph B. Margolick, another Hopkins co-author. "That has not happened."
Some patients in the studies have been taking the drug cocktail for up to three years and their resting blood cells still contain virus.
Dr. David Ho of the Aaron Diamond AIDS Research Center in New York, a co-author of one of the studies, said that scientists now may start searching for a ways to eradicate the latent virus. That would require a new treatment mechanism, he said, because all of the AIDS drugs now in use attack the virus only when it is reproducing.
Copyright 1997/The Associated Press. Reproduced with permission. Reproduction of this article (other than one copy for personal reference) must be cleared through the Permissions Desk, The Associated Press, 50 Rockefeller Plaza, New York, NY 10020.
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Copyright © 1997 - Associated Press. Reproduction of this article (other than one copy for personal reference) must be cleared through the AP Permissions Desk.
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