-- Doctors in Germany report they have cured an HIV

-- Doctors in Germany report they have cured an HIV-positive American of the AIDS virus after performing a stem cell transplant to treat his leukemia.

But experts caution that while the man's outcome seems promising, the risky procedure might not work on otherwise healthy people with HIV and probably won't yield an overall cure for AIDS. Still, if the patient's HIV doesn't resurface, this would mark the first time HIV has been wiped out in any patient.

In 2007, Timothy Ray Brown received a stem cell transplant to treat his leukemia, a cancer of the blood. The procedure involves destroying a patient's natural immune system with chemotherapy and radiation, then boosting it back up by inserting bone marrow or blood stem cells from a healthy donor.

Brown's donor was not only a perfect match for his blood and bone marrow type but also happened to have a rare, inherited genetic mutation that makes carriers virtually immune to HIV. The donor's cells took root in Brown's body and multiplied. Three years later, Brown's leukemia is in remission, and he's also HIV-negative.

The German doctors' findings were published last week in Blood, the journal of the American Society of Hematology. "Our results strongly suggest that cure of HIV has been achieved in this patient," they wrote.

Other experts warn that HIV could still be present -- but dormant and undetectable -- in the patient's blood.

"'Cured' is a strong word. But this is very encouraging," Dr. David Scadden, co-director of the Harvard University Stem Cell Institute, told The Miami Herald. "From all indications, there was no residual virus. It's as good an outcome as one could hope."