Two men who stopped HIV treatment after bone marrow transplants have found the virus has started replicating again, months after tests showed they were negative.
The researchers who were conducting their care say the discovery is “disappointing but scientifically significant”.
The two HIV-positive men, who were both from Boston, had been given their respective transplants in 2008 and 2010 in order to treat Hodgkin’s lymphoma.
Bone marrow is where new blood cells are made and thought to be a major reservoir for HIV.
Alongside the transplants, they continued to take anti-retrovirals for the virus, but scientists found evidence of HIV in their bodies declining as the cells were replaced with the donor’s cells.
Eight months after the surgery, the patients tested HIV-negative and the patients stopped taking their anti-retroviral medication.
However, traces of the virus were found in one patient’s bloodstream 12 weeks after stopping treatment, with the second patient a further 20 weeks later.
Timothy Heinrich, a physician-researcher in the Division of Infectious Diseases at Brigham and Women’s Hospital, says this identifies that the reservoir for HIV is more complex than first thought.
He added: “Our current standards of probing for HIV may not be sufficient to inform us if long-term HIV remission is possible if antiretroviral therapy is stopped.”
Dr Daniel K. Kuritzkes, another researcher at Brigham and Women’s Hospital, believes the cases of the two men show the HIV virus may continue to exist regardless of its absence in the blood.
He said: “Our results also show that the immune system can play a major role in reducing the viral reservoir, but may not be able to do the job alone.
“It is likely that a combination of drugs and immune therapies that target the reservoir will be needed to establish long-term remission of HIV infection.”