Genetic Tests Predict AIDS Vulnerability
By Randy Dotinga, HealthDay Reporter
HealthDayNews — Researchers have developed genetic tests and a statistical formula to measure the body’s ability to prevent HIV from developing into AIDS.
They say they can predict whether the virus has enough pre-programming to evade the immune system’s defense systems.
The researchers also say they’ve discovered that African-Americans have higher levels of immunity, perhaps because the virus in the United States has learned to target the immune systems of Caucasians.
While the findings are potentially significant, they won’t yield new treatments anytime soon, the researchers say.
The findings “give us insight into the evolution of the virus, which is its primary weapon,” says Thomas Kepler, interim director of the Center for Bioinformatics and Computational Biology at Duke University, and co-author of a study in the June 22 issue of the journal Nature Medicine.
Kepler and his colleagues examined genetic tests performed on the blood samples of 562 HIV-positive men enrolled in a Chicago AIDS study.
The researchers focused on two immune system molecules — known as human leukocyte antigen A and B — that bring pieces of suspect intruders to T-cells for inspection. The T-cells, the soldiers of the immune system, then decide whether to destroy the intruders.
“The strategy that humans have evolved is to carry a fairly large number of the [antigens], in the hopes that one of them will be sufficient to deal with any given pathogen,” Kepler says.
The problem with HIV is that some of the immune system antigens don’t do a good job of responding to the intruders. To figure out which ones do the best job, the researchers developed a statistical method to compare various types of antigens to the level of HIV in the blood of the Chicago study patients.
The researchers found that more common types of antigens had a tougher time fighting off the virus. Patients with less common types — particularly those found in African-Americans — were more easily able to battle the infection.
The AIDS virus may have learned how to attack the most common immune system antigens in Caucasians, Kepler says.
“Our hypothesis is that HIV has evolved to attack the largest target, while leaving the smaller targets behind. It [the virus] just decided that the best strategy is to learn how to deal with the most common weapons in the human armament,” he explains.
In Africa, where AIDS is mainly a disease of blacks, the virus may have done the same thing, he says. There, a similar study might show that the immune systems of whites are best equipped to resist the virus, Kepler says.
While the study findings could help researchers who are working on an AIDS vaccine, they may not immediately result in better treatments for AIDS patients, Kepler adds.
Another expert agrees.
“The science may have profound applications for future research, but it will probably mean nothing medically today,” says Michael Allerton, HIV operations policy leader with Kaiser Permanente Health Plan in Northern California.
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On the Net:
U.S. Centers for Disease Control and Prevention
National Institute of Allergy and Infectious Diseases
Center for Bioinformatics and Computational Biology
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