After undergoing a bone marrow transplant to treat leukemia, an AIDS patient may now be cured of the HIV virus, The Wall Street Journal reports.  

For the transplant, Gero Hütter, MD, of the Medical University of Berlin, a hematologist who does not specialize in AIDS, purposely used the bone marrow of a donor who has a naturally occurring genetic mutation that causes his cells to be immune to almost all strains of HIV. Although the patient has ceased taking AIDS medication, the virus has not been detected in his blood, brain or rectal tissue for more than 600 days.

The transplant may be a therapeutic breakthrough that could possibly offer an alternative to antiretrovirals, medication that prevents the virus from replicating but is costly since it must be taken daily for life.

The case was presented to scientists at this year’s Conference on Retroviruses and Opportunistic Infections, and in September, the American Foundation for AIDS Research assembled to discuss the case. Most researchers believed that the patient could possibly still have some HIV but that it isn’t enough to cause a raging infection, making him “functionally cured.”