Getting in the Way

A new treatment for HIV could lead to a cure for the disease, reports Scientific American's Bob Roehr. Finding ways to block HIV has been an ongoing process, and the pieces of the puzzle have been slowly uncovered over the years. First, researchers came to understand that HIV enters a cell by using a CD4 receptor molecule and then attaching to the CCR5 co-receptor. Then, researchers found that anyone with a delta-32 mutation to the gene that encodes CCR5 has fewer receptors on their cells and could be more resistant to HIV infection, Roehr says. "Inherit a mutant gene from both parents and the result is no CCR5 receptors at all, which makes it almost impossible for HIV to enter a cell. About 1 percent of Europeans have this double variant," he adds. The small molecule HIV drug maraviroc was a result of this discovery. Then, doctors treated a man with HIV who had developed leukemia with radiation to destroy his immune system and gave him a bone marrow transplant from a donor with the CCR5 mutation. His HIV had apparently been cured, Roehr says. Although destroying the immune system of every HIV patient isn't feasible, researchers took this discovery and built on it, developing a zinc fingers technology "that can home in on the CCR5 section of cellular DNA and artificially create a functional equivalent of the delta-32 mutation," he adds. The treatment is being tested.