What: Viral load—the amount of virus in the blood of an HIV-infected person—has long been viewed as the chief indicator of how quickly someone infected with HIV infection progresses to AIDS. New data published in Nature Immunology builds on previous work that suggests that several other factors in addition to viral load significantly contribute to disease progression rates.
Researchers led by Sunil Ahuja, M.D., of the University of Texas Health Science Center in San Antonio, examined genetic information from more than 3,500 HIV-1 infected and uninfected individuals. They found that individuals who had specific combinations of two genes—CCR5, which helps facilitate HIV entry into the cell, and CCL3L1, an immune response gene—were much more likely to have reduced immune responses and a greater decline in CD4 T cells, two hallmarks of progressive HIV disease. Further, the researchers found that in HIV-infected subjects, viral load contributed only 9 percent to the variability in rate of progression to AIDS; variations in CCR5 and CCL3L1 combined accounted for 6 percent variability in AIDS progression rates.
The findings may have implications for the care of HIV-infected individuals in terms of being able to more effectively predict the course of HIV disease. With further research, this work may lead to additional markers, which along with viral load may serve as indicators of HIV progression. The study was funded by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health.