September 21, 2012
Researchers at the University of California, Los Angeles, have discovered why some HIV positive individuals progress more rapidly than others to full-blown AIDS. The research was published in the Journal of Virology. Slow progressors carry the gene called HLA-B*57 (B57) an immune gene variant found in less than five percent of the population, but in 40-85 percent of slow progressors. Among those with the B57 gene, the speed of disease progression also varies. The key to the variation is a killer T-cell immune response occurring early in the HIV infection. It targets a section or epitope of the HIV protein known as IW9. The researchers compared only the killer T-cell responses among those with the B57 gene, using blood taken shortly after HIV infection from 14 HLA-B57 carriers with known infection dates and known long-term outcomes. It was found that those whose killer T-cell immune response targeted the IW9 epitope early in the infection had significantly longer times until onset of AIDS than those who did not. The researchers note that the study sample was small -- 14 subjects -- and that the study should be repeated with a larger number of subjects. Also, the results point to a correlation with, rather than causation of slower disease progression among B57 carriers who target the IW9 epitope soon after infection.
The full report was published in the Journal of Virology (October 2012; 86:10505-10516).