A cure for HIV may have been found by doctors in Germany who were treating a man for acute myeloid leukemia. The man also had Human Immunodeficiency Virus, commonly known as HIV.

The man who is thought to have been cured from HIV is Timothy Ray Brown. He is a U.S. citizen who is living in Berlin. During his treatment for the leukemia he underwent chemotheapy, which was followed by a bone marrow transplant. The bone marrow was provided by a person that had a rare mutation which made them virtually immune to HIV.

More than three years after the treatement, tests on Brown can find no signs of HIV infection. Levels of HIV antibodies in his blood have dropped. Viral load testing (RNA) and tests for viral DNA within his cells, which would normally indicate the presence of HIV, come back negative.

It’s suspected that the combination of chemotherapy and the bone marrow transplant from a person with the rare mutation are what have caused this apparent miracoulous recovery from HIV. But doctors say it is still far from a proven cure and that treatment could be difficult. Only 1 of every 100 Caucasians in northern and western Europe have the special mutation that Brown’s transplant doner carried. And this is the only patient that has undergone this treatment.

In an AIDS on msnbc.com story, Jerome Zack, a University of California, Los Angeles, researcher who studies HIV but was not a part of the study, said:  “I’m extremely excited about the result. It suggests that at least in this one individual, there’s a long-term benefit to this approach.”

The study was published in the medical journal Blood this week.