Scientists have discovered why some people who are infected with the AIDS virus have a rapid downhill course, becoming gravely ill and dying within a few years, while most infected people live for years without major symptoms.
The key is a gene that acts like a molecular rheostat, turning up or down the activity of another gene that produces a protein the AIDS virus uses as a doorway to enter cells.
A normal variant of the rheostat gene accelerates the onslaught of the AIDS virus in about a fifth of people whose HIV infection progresses rapidly.
About one person in 10 has the gene variant, which is described in a report in today's issue of the journal Science.
As a result, said Dr. Stephen J. O'Brien, the head of the group that discovered the gene's effect, "if they get infected with HIV, they'll go fast." O'Brien is chief of the laboratory of genomic diversity at the National Cancer Institute in Frederick, Md.
Scientists say the discovery might help them devise treatment strategies, but not actual treatments for HIV.
O'Brien said the discovery's immediate importance was in evaluating AIDS vaccines, because it was important to know a group's genetic susceptibility in deciding whether a vaccine slowed the course of the disease.
But, researchers say, the result is most significant as a harbinger of the future of disease research.
It fleshes out a picture of HIV infections that illustrates how a gene that appears to have no obvious relationship to a disease can determine the outcome of the complex battle between the body, with all its cells and organs, and a disease.
"AIDS is leading the way," said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.
Doctors treating AIDS patients have long been interested in the unpredictable nature of the disease. While, on average, the time from infection with HIV to disease is about 10 years, there are people at either end of a wide spectrum.
"People with HIV come to the clinic and could live for more than 15 years and be healthier than you or I," said Dr. Sunil Ahuja, an AIDS researcher at the University of Texas Health Science Center in San Antonio. Or, he said, "they could die two or three years later."
With just a few years of concentrated effort, AIDS researchers have discovered genetic variations that normally have no consequence, yet can cause the most striking features of infections with HIV.
Pub Date: 12/04/98