Now researchers are reporting a second patient has lived 18 months after stopping HIV treatment without sign of the virus following a stem-cell transplant.
The title is similar to the first known case of a cured HIV-positive patient.
"While it is too early to say with certainty that our patient is now cured of HIV, and doctors will continue to monitor his condition, the apparent success of stem cell transplantation offers hope in the search for a long-awaited cure for HIV/AIDS", said Professor Eduardo Olavarria of Imperial College Healthcare NHS Trust and Imperial College London. Highly sensitive tests showed no trace of the man's previous HIV infection. Scientific research into the complex virus has in recent years led to the development of drug combinations that can keep it at bay in most patients.
"If we can understand better why the procedure works in some patients and not others, we will be closer to our ultimate goal of curing HIV", said Cooke, who was not involved in the case study.
The man has chosen to remain anonymous, with scientists referring to him as "the London patient". "Everybody believed after the Berlin patient that you needed to almost die basically to cure HIV, but now maybe you don't".
The donor-who was unrelated-had a genetic mutation known as "CCR5 delta 32", which confers resistance to HIV.
His doctors, according to the Evening Standard, said highly sensitive tests showed no trace of the infection nearly three years after a stem cell transplant.
READ ALSO: Good news! Although the interventions that the two patients received could only be used on a tiny fraction of the 37 million HIV-infected people worldwide, their stories point to cure strategies that could be more widely applicable.
"I never thought that there would be a cure during my lifetime", he said.More news: Liberal Treasury Board president resigns amid SNC-Lavalin scandal
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Compared to Brown, the London patient had a less punishing form of chemotherapy to get ready for the transplant, didn't have radiation and had only a mild reaction to the transplant.
"Two factors are likely at play - the new bone marrow is resistant to HIV and also the new bone marrow is actively eliminating any HIV-infected cells through something called graft versus host disease".
The London patient is 36 on this list.
Professor Gupta, now at Cambridge University, treated the patient in the United Kingdom capital when he was working at University College London.
This is the second time a patient treated this way has ended up in remission from HIV. They also plan to present details in Seattle at the Conference on Retroviruses and Opportunistic Infections, which began Monday.
The UK researchers say it may be possible to use gene therapy to target the CCR5 receptor in people with HIV, now they know the Berlin patient's recovery was not a one-off.
"After 2 years, we'll be talking more about 'cure, '" Gupta says.
"I am an optimist because I'm a scientist and vice versa", Henrich said.
One possibility, said Deeks and others, is to develop gene-therapy approaches to knock out CCR5 on immune cells or their predecessor stem cells.