Two groups of people especially intrigue AIDS researchers: those who resist HIV infection despite repeated exposure to the virus and those who progress very slowly to AIDS after infection. Understanding what makes these individuals different could lead to new vaccines and treatments, and a study published this week in the early online edition of the journal AIDS brings scientists closer to that goal. It shows that a tiny variation in an immune system gene called RANTES can be a double-edged sword, substantially increasing one's susceptibility to HIV infection, but subsequently slowing down the disease's progress.
"This study offers the first genetic evidence that RANTES affects the risk of HIV transmission," says Dr. Anthony S. Fauci, M.D., director of the National Institute of Allergy and Infectious Diseases (NIAID). "It also adds to the evidence that RANTES can slow the progression to AIDS in HIV-positive individuals, lending support to the search for a drug that mimics this gene's action."
"Some people don't become infected with HIV despite repeated, high-risk behavior. And some HIV-positive people progress rapidly to AIDS while others never do. We wanted to see what tips the scales," says immunologist Philip M. Murphy, M.D., the study's senior author. Dr. Murphy and his colleagues looked at known RANTES gene variations in HIV-positive and HIV-resistant individuals who participate in the Multicenter AIDS Cohort Study (MACS), a project funded by NIAID. The MACS is the largest continually monitored group of HIV-infected and at-risk people in the world. The genetic differences Dr. Murphy's team studied, called single nucleotide polymorphisms, or SNPs ("snips") for short, are the smallest possible, involving a change in just one base pair, or "rung," of the DNA ladder.
Still, these tiny SNPs can have a big impact. One such SNP appears significantly more often in HIV-positive than in HIV-resistant individuals. In fact, the scie
Contact: Jeff Minerd
NIH/National Institute of Allergy and Infectious Diseases