Two patients have been taken off their HIV drugs after bone-marrow transplants seemed to clear the virus from their bodies, doctors report.
美国两名接受骨髓移植手术的病人已停止服用艾滋病药物，该手术似乎清除了他们体内的艾滋病毒。
One of the patients has spent nearly four months without taking medication with no sign of the virus returning.
The team at Brigham and Women's Hospital, in the US, caution that it is far too soon to talk about a cure as the virus could return at any point.
The findings were presented at the International Aids Society Conference.
It is difficult to get rid of an HIV infection because it hides inside human DNA, forming untouchable "reservoirs" in body.
Anti-retroviral drugs keep the virus in check within the bloodstream - but when the drugs stop, the virus comes back.
HIV gone?
The two men, who have not been identified, had lived with HIV for about 30 years.
They both developed a cancer,
lymphoma（淋巴瘤）, which required a bone-marrow transplant.
Bone marrow is where new blood cells are made and it is thought to be a major reservoir for HIV.
After the transplant, there was no detectable HIV in the blood for two years in one patient and four in the other.
The pair came off their anti-retroviral drugs earlier this year.
One has gone 15 weeks, and the other seven, since stopping treatment, and no signs of the virus have been detected so far.
Dr Timothy Henrich told the BBC the results were exciting. But he added: "We have not demonstrated cure, we're going to need longer follow-up.
"What we can say is if the virus does stay away for a year or even two years after we stopped the treatment, that the chances of the virus rebounding are going to be extremely low.
"It's much too early at this point to use the C-word [cure]."
It is thought that the transplanted bone marrow was initially protected from infection by the course of anti-retrovirals. Meanwhile the transplant also attacked the remaining bone marrow, which was harbouring the virus.
However Dr Henrich cautioned that the virus could be still be hiding inside brain tissue or thegastrointestinal（胃肠的）
track.
"If [the] virus does return, it would suggest that these other sites are an important reservoir of infectious virus and new approaches to measuring the reservoir at relevant sites will be needed to guide the development of HIV curative（有疗效的）
strategies," he said.
