Researchers at the Brigham and Women's Hospital in Boston said in
July that they were unable to detect any signs of HIV in the blood of
either patient about eight months after they had undergone a bone-marrow
transplant for lymphoma cancer.
The doctors said at the time that
the treatment may have resulted in a "functional cure" that eliminated
residual pockets of HIV, offering hope that it may be possible to use
this knowledge to find ways of ridding the virus totally from a
Both men stopped taking anti-retroviral therapy in
the spring, however one of the Boston patients began to show signs of
an HIV rebound in August, while the second patient had a relapse in
November. Both are now responding well to anti-retroviral drugs, said
Timothy Henrich, a physician-researcher at the
hospital said that the return of detectable levels of HIV in the two
patients is "disappointing but scientifically significant" because it
shows that the virus persists even when some of the most sensitive blood
tests fail to detect it.
"Through this research we have
discovered [that] the HIV reservoir is deeper and more persistent than
previously known and that 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 Henrich said.
also learned that there may be an important long-lived HIV reservoir
outside the blood compartment. Both patients have resumed therapy and
are currently doing well. I am thankful for their commitment to research
and our shared dedication in understanding this virus to benefit all
HIV patients," he said.
The Boston patients have been compared to
Timothy Brown, the "Berlin patient", who was also "cured" of HIV
following a different type of stem-cell transplant to treat leukaemia.
The donor of the transplanted bone marrow also carried a specific
mutation known to interfere with HIV's ability to infect white blood
Mr Brown, who now lives in San Francisco, received the
transplant in 2007 and appears to remain free of detectable levels of
HIV in his bloodstream. However, his transplant carries a high risk of
death and is considered too dangerous for widespread treatment of
HIV-Aids, scientists said.
In the case of the two Boston patients,
the transplanted bone marrow came from ordinary donors. One of the men
received his bone-marrow transplant in 2008 while the other had his in
2010 - and both stopped taking antiretroviral drugs in earlier this year
before suffering viral rebound.
Brigham and Women's Hospital
said: "Physician-researchers will continue to monitor the patients and
continue to measure their HIV levels as part of a new study of the very
early initiation of anti-retroviral therapy after HIV rebound."
only other case of a "functional cure" for HIV is a baby in Mississippi
whose mother was infected with the virus but did not realise it until
she was in labour.
The baby, who was also infected, was given
anti-retroviral drugs within hours of birth and has remained free of the
virus for the past three years. Doctors, however, now prefer to
describe the baby as being in "remission" rather than being "cured".