October 22, 2007
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.
"CCL3L1 and CCR5 influence cell-mediated immunity and affect HIV-AIDS pathogenesis via viral entry-independent mechanisms" by Matthew J. Dolan et al. Nature Immunology (Published online Sunday, October 21, 2007). DOI: 10.1038/ni1521 (2007).
Anthony S. Fauci, M.D., NIAID Director, and Opendra Sharma, Ph.D., a program officer in NIAID's Division of AIDS Pathogenesis and Basic Research Branch, are available to comment on this article.
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