As breakthroughs go, finding a cure for AIDS would be pretty high on the list, and that's what Berlin doctors believe they have achieved. US citizen Timothy Ray Brown was treated for acute myeloid leukaemia in 2007, with doctors carrying out a stem cell transplant using bone marrow resistant to HIV infection. That marrow lacked the CCR5 co-receptor on CD4 cells - to which the most common form of HIV initially binds with - and by replacing all of the patient's infected CD4 cells, the HIV has seemingly been eradicated.
"Doctors chose stem cells from an individual who had an unusual genetic profile: a mutation inherited from both parents that resulted in CD4 cells that lacked the CCR5 receptor. This mutation, called CCR5 delta 32 homozygosity, is present in less than 1% of Caucasians in northern and western Europe, and is associated with a reduced risk of becoming infected with HIV" aidsmap
It seems the combination of chemotherapy and CCR5-lacking stem cell treatment is the key to this particular breakthrough. The chemotherapy - which took place prior to the transplant - killed off most immune cells in Brown's body, and then the donor CD4 cells repopulated over the course of two years. Various tests - including viral load testing (RNA), tests for viral DNA within cells, and in cerebrospinal fluid - indicated that HIV antibody levels had declined to the point that the patient has no antibody reactivity to HIV core antibodies.
Scientists are quick to point out the unusual conflation of factors that led to Brown's treatment, and that the process itself was not for the faint-hearted, but are hopeful that genetically engineered stem cells could be used in future for HIV cures. "For me" said Dr Gero Hütter, who was in charge of the treatment program, "it is important to have overthrown the dogma that HIV can never be cured."
[via Derren Brown]