Friday, September 26, 2014

How Did This Man Rid Himself Of HIV?

Timothy Ray Brown, known by many researchers as "the Berlin patient," is the only person to have been cured of an HIV infection. 

Timothy Ray Brown, known by many researchers as "the Berlin patient," is the only person to have been cured of an HIV infection 

Researchers are closer to unraveling the mystery of how Timothy Ray Brown, the only human cured of HIV, defeated the virus, according to a new study. Although the work doesn’t provide a definitive answer, it rules out one possible explanation.

Brown remains one of the most studied cases in the HIV epidemic’s history. In 2006, after living with the virus for 11 years and controlling his infection with antiretroviral drugs (ARVs), he learned that he had developed acute myeloid leukemia. (The leukemia has no known relationship to HIV infection or treatment.) Chemotherapy failed, and the next year Brown, an American then living in Berlin, received the first of two bone marrow transplants—a common treatment for this cancer—and ditched his ARVs. When HIV-infected people stop taking ARVs, levels of HIV typically skyrocket within weeks. Yet researchers scouring Brown’s blood over the past 7 years have found only traces of the viral genetic material, none of which can replicate.

Today, researchers point to three different factors that could independently or in combination have rid Brown’s body of HIV. The first is the process of conditioning, in which doctors destroyed Brown’s own immune system with chemotherapy and whole body irradiation to prepare him for his bone marrow transplant. His oncologist, Gero Hütter, who was then with the Free University of Berlin, also took an extra step that he thought might not only cure the leukemia but also help rid Brown’s body of HIV. He found a bone marrow donor who had a rare mutation in a gene that cripples a key receptor on white blood cells the virus uses to establish an infection. (For years, researchers referred to Brown as “the Berlin patient.”) The third possibility is his new immune system attacked remnants of his old one that held HIV-infected cells, a process known as graft versus host disease.

In the new study, a team led by immunologist Guido Silvestri of Emory University in Atlanta, designed an unusual monkey experiment to test these possibilities.

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