When someone becomes infected with HIV, the amount of virus in the blood spikes as the virus multiplies. After this peak, the amount of virus in the blood, known as the viral load, gradually decreases and then levels off, a period during which patients do not exhibit symptoms of their disease. The viral load during this leveling out is an indication of how well the patients' own immune system is battling the virus, and this is the point in the infection's natural history that the researchers studied.
The CHAVI investigators wanted to study those patients who had many sequential blood samples taken during this plateau in viral load. Before their analyses began collaborators in the EuroChavi consortium, coordinated by Amalio Telenti at the University of Lausanne, sifted through data collected from more than 30,000 patients who had blood samples taken as a part of nine studies in Europe and Australia. They arrived at 486 patients who had had multiple blood tests documenting viral loads after infection and before they started receiving antiretroviral treatment.
The three polymorphisms were identified after all the blood samples of the selected patients were screened for more than 555,000.
Additionally, the researchers discovered many other genetic variants that may confer protection for patients but whose effects did not reach statistical significance in the study. However, some of these polymorphisms could ultimately be shown to play a major role when future analyses involving more patients are performed, the researchers said.
Patients involved in the study came from Switzerland, Italy, United Kingdom, Australia, Spain, and Denmark. The genetic analysis was performed at Duke and the University Lausanne, Switzerland. CHAVI is a consortium of scientists from Duke, Harvard, Oxford, University of North Carolina-Chapel Hill, and