May 21, 2003
Canadian and U.S. scientists reported Thursday that people who stay healthy years after HIV infection are more likely than other HIV patients to be infected with virus that has a particular protein alteration. The finding offers another possible explanation why a small number of people with HIV never develop AIDS, and points toward new therapies that might prevent the progression of HIV in other patients, as well.
Experiments with an HIV protein -- viral protein R (Vpr) -- revealed that altering or deleting the protein greatly decreased the number of immune cells destroyed by HIV, the process that enables HIV to progress to AIDS. Treatments that block Vpr may help infected people to stay healthy, said study author Dr. Andrew Badley of the Mayo Clinic in Rochester, Minnesota. "Since mutations in Vpr can alter the outcome of HIV disease, it is possible, if not likely, that we can develop inhibitors of Vpr that may also modify disease outcome," Badley said.
In the small number of HIV patients known as nonprogressors, levels of the virus remain low, even without treatment, and AIDS does not develop. Badley and colleagues examined the makeup of HIV extracted from the blood of people with HIV, some of whom were nonprogressors. Once researchers identified that a particular HIV mutation was present more often in nonprogressors, they designed HIV samples that contain normal or mutated forms of Vpr, and some samples lacking the protein. Badley and his team then mixed those different forms of HIV with human blood cells, and discovered that each type of virus had a different effect on immune cells.
Badley explained that HIV in nonprogressors likely succeeds in killing immune cells, but at such a slow rate, people are able to make new immune cells fast enough that their immune system does not become compromised. He noted that he and his colleagues are currently looking at developing Vpr inhibitors. "Certainly, we're talking a number of years, as opposed to a number of months" before a new treatment would be available for people, he said. The full study, "Vpr R77Q Is Associated with Long-Term Nonprogressive HIV Infection and Impaired Induction of Apoptosis," is published in the May 15 issue of the Journal of Clinical Investigation (2003;111(10):1547-1554).
05.15.03; Alison McCook