In 2008, one man, Timothy Ray Brown, was cured of HIV. Also known as the "Berlin patient," Brown was considered cured of his infection after receiving two bone-marrow transplants to treat a separate disease he had been diagnosed with a few years earlier: acute myeloid leukemia. The bone marrow he received came from a donor whose genes carried a rare mutation that made them resistant to HIV, known as CCR5-delta 32, which was transferred on to Brown. Traces of the virus were seen in his blood a few years later, but remained undetectable despite him not being on antiretroviral treatment, meaning he was still clinically cured of his infection, according to his clinicians. Despite various attempts on patients after him by scientists using this same approach, including a similar transplant in two Boston patients, Brown remains the only person known about who has been cured of HIV.

But a new study presented Sunday at the 2016 Towards an HIV Cure Symposium -- ahead of the 21st International AIDS conference in Durban, South Africa, this week -- revealed data on a new set of HIV positive patients whose reservoirs of HIV have fallen to very low levels after receiving a range of stem cell transplants similar to Brown's. READ MORE