"The so-called London Patient has now been off ART for 19 months with no viral rebound which is impressive, but I would still be closely monitoring his viral load", Sharon Lewin, IAS Governing Council Member and Co-Chair of the Towards an HIV Cure initiative, said.
Over a decade ago, a German doctor announced the first case of a patient who had been cleared of the virus. He then underwent a bone-marrow transplant in 2016 after receiving a diagnosis of advanced Hodgkin's lymphoma, initially having been treated with chemotherapy.
The new patient has chosen to remain anonymous, and the scientists referred to him only as the "London patient".
Blood cells of an infected person are replaced by someone who is immune to HIV through a genetic mutation which stops the virus attaching to cells.
However, bone-marrow transplants are traditionally unsafe and painful.
Gupta, now at Cambridge University, treated the London patient when he was working at University College London. HIV can mutate from using CCR5 to relying on CXCR4, but in order to do that, it needs to be actively replicating. CCR5 is known to be a co-receptor for HIV, so mutations in it can help people to become resistant to infection. Scientists have wondered, however, whether this good fortune could be shared around by injecting stem cells from people with two Δ32 copies into HIV patients.
As of 2017, there were approximately 36.9 million people worldwide living with HIV/AIDS.
The London patient is only the world's second person to go into remission from HIV.
The experiment, which is under investigation and does not even appear to have succeeded at creating the desired deletion in twin girls, was widely condemned as unethical, a premature and reckless use of an unproven technology and medically unnecessary because of a multitude of other ways to prevent HIV transmission. "It shows the Berlin patient was not just a one-off, that this is a rational approach in limited circumstances", said Daniel Kuritzkes, chief of infectious diseases at Brigham and Women's Hospital, who was not involved in the study.
Experts and researchers talking about this second case, known as the "London Patient", are publicly stating that the patient is "in long-term remission", not "cured".
"HIV is a retrovirus, which means that it integrates its genetic information into a host cell's own DNA".
When it comes to the search for an HIV cure, in some ways the urgency has gone. Not until the world heard of how the London patient, who was - to a lesser degree than Brown - battling with cancer and the virus.
Nonetheless, future research into how this HIV receptor functions could bring us a lot closer to an eventual cure for HIV, which now infects around 37 million people worldwide.