A bone marrow transplant from an HIV resistant donor has made it possible for a second person in the world to be cleared from an HIV infection 100 per cent. The man in London received stem cells and he was declared completely freed from the virus within 18 months of stopping the antiretroviral drug therapy. The highly sensitive test used on him did not detect any traces of the virus left in the blood of the patient, giving the world hope for the development of an effective AIDS cure.