A case report published in the New England Journal of Medicine last week details a man who was HIV+ and, following a bone marrow transplant, now has no detectable signs of the virus.
Human Immunodeficiency Virus (HIV) enters and destroys cells of the immune system, eventually causing Acquired Immunodeficiency Syndrome (AIDS). To enter the cells it attaches to proteins on their surface, including one called CCR5. People with a certain variation of CCR5 are resistant to infection with HIV. The mutation occurs in 1-3 per cent of Europeans.The new study details a HIV+ man who had been living with the virus for 10 years and taking medication known as Highly Active Anti-Retroviral Therapy (HAART) to successfully control it for four years. He then developed acute myeloid leukaemia and to treat the condition received two bone marrow transplants. The second donor had the CCR5 mutation that is resistant to HIV. After the bone marrow transplant the patient stopped taking HAART and, 20 months later, had no signs of leukaemia or, unexpectedly, HIV. After the transplants, the patient's immune cells in the blood had the HIV resistant CCR5 mutation.
Usually after a person stops taking HAART, HIV levels quickly increase. In this case the virus remained undetectable in the patient's blood and bone barrow. It is possible that the virus is still present in other cells in the body, such as cells of the lymph nodes, brain, or gut, where it can 'hide' for many years.
The authors of the paper, led by Dr Gero Hutter of the Berlin Charite Hospital, Germany, said that this case report shows the importance of CCR5 in HIV infections. Unfortunately, a single case does not mean that bone marrow transplants would be able to treat HIV in other people. Also, the transplants are dangerous, so it is unlikely that they will be able to be used as an HIV treatment. However, modifying or deactivating CCR5 with gene therapy or drugs may become targets for researchers.
Currently, 33 million people are infected with HIV worldwide. Since is discovery in 1984, no vaccine or cure has been developed. The virus can be controlled using HAART, but this medication is life-long, with toxic side effects, and is generally unavailable to the majority of infected people who live in the developing world.