Timothy Brown still remembers his reaction to the diagnosis of HIV.
"I was terrified. I knew people who were struggling with the disease. Some of my friends had already died from it," Mr Brown said.
"At that time most of us viewed an HIV diagnosis as a death sentence."
A year later, however, it became possible to treat Mr Brown with a combination of drugs which kept him from developing AIDS.
In 2006 he was diagnosed with acute myeloid leukaemia and was to receive a bone marrow transplant.
"I underwent total body irradiation to wipe out my body's immune system before receiving the transplant. I still have no trace of HIV in my body."