The patient shows no signs of HIV after three months without antiviral drugs, doctors have said.
The case of the “Dusseldorf patient” was reported at a scientific conference this week, but doctors said their remission is still at an early stage.
It came hours after researchers reported a “London patient” was the second ever person to see their HIV-positive status “cured” by a bone marrow transplant – which effectively replaces and reboots the cells of the immune system where HIV persists.
The London patient, who has decided to remain anonymous, has been off virus-suppressing drugs for 18 months and has no detectable traces of HIV, researchers reported in the journal Nature earlier this week.
This third case has only been off the medication for three months, but biopsies of tissue taken from lymph nodes and the gut show no sign of infection, doctors told the Conference on Retroviruses and Opportunistic Infections in Seattle.
Bone marrow transplants have been known as a possible “cure” for HIV since the 2007 case of American Timothy Ray Brown, known as the “Berlin patient”.
He was diagnosed with leukaemia, a cancer of the white blood cells which make up the immune system, and was given a transplant to replace his cancerous cells with a donors after chemotherapy and radiotherapy.
The crucial factor for the patients “cured” of HIV in this way is that their donor carried a mutation in a gene called CCR5 which is only found in around 1 per cent of people in Western Europe – and is even more rare elsewhere.
People with a CCR5 mutation are naturally resistant to HIV and when used in a bone marrow transplant it effectively means the virus cannot return.
The procedure is unlikely to be a viable solution for the millions with HIV. In part because of the scarcity of CCR5 donors, but chiefly because of the risks of the procedure, which can see the donated cells rejected and has only been attempted in patients with life-threatening blood cancers – such as non-Hodgkin lymphoma in the case of the London patient.
Doctors say they are tracking a handful of other people who had HIV and have then had a CCR5 bone marrow transplant thanks to a register of CCR5 donors compiled by the IciStem collaboration.
This includes two patients who are still taking anti-retroviral medicines, as stopping taking the drugs risks harming their immune system and becoming infectious again.
Now multiple cases have shown that the CCR5 mutation can be protective against HIV researchers have said inserting the gene with technologies like Crispr could be a more viable way of treating it in future.
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