For just the second time ever a HIV patient is in sustained remission from the virus in what was hailed by experts yesterday as proof that the AIDS-causing condition could one day be curable.

Ten years almost to the day since the first confirmed case of an HIV-infected person being rid of the deadly disease, a man known only as the "London patient" has shown no sign of the virus for nearly 19 months, doctors reported in the journal Nature.

Both patients underwent bone marrow transplants to treat blood cancers, receiving stem cells from donors with a genetic mutation present in less than one percent of Europeans that prevents HIV from taking hold.

"It is a landmark. After 10 years of not being able to replicate (the first case), people were wondering if this was a fluke," said lead author Ravindra Gupta, a professor at the University of Cambridge.

"I think it is important to reaffirm that this is real and it can be done," Gupta told AFP.

Millions of people infected with HIV around the globe keep the disease in check with so-called antiretroviral therapy (ARV), but the treatment does not rid patients of the virus.

Close to 37 million people are living with HIV worldwide, but only 59 percent are receiving ARV. Nearly one million people die every year from HIV-related causes.

A new drug-resistant form of HIV is also a growing concern.

The first sustained remission survivor, announced in 2009 as "the Berlin patient" and later named as American Timothy Brown, was given two transplants and underwent total body irradiation to treat leukaemia -- a process that nearly killed him.

Gupta said that while a second successful transplant did not constitute a generalised cure, his team's work showed that even milder forms of treatment can achieve full HIV remission.

The International AIDS Society yesterday said in a statement that results from the second patient "reaffirm our belief that there exists a proof of concept that HIV is curable".