In a major setback in the search for AIDS cure, a child in the US, who was thought to have been cured of HIV after intensive drug therapy, has been found with detectable levels of the virus, scientists say.
Two months shy of her fourth birthday, paediatricians gave the 'Mississippi baby' bad news: the HIV virus, once seemingly vanquished by aggressive antiretroviral therapy soon after her birth, had rebounded.
"It felt very much like a punch to the gut," said Hannah Gay, a paediatric HIV specialist at the University of Mississippi Medical Centre in Jackson.
The young girl will now face years, if not a lifetime, of antiretroviral therapy. And researchers are now scrambling to determine how this will affect clinical trials aiming to repeat the child's apparent cure.
The 'Mississippi baby' was born to an HIV-positive mother who had not been treated with anti-retroviral drugs during her pregnancy.
Doctors began treating the child before she was 30 hours old, but the family stopped antiretroviral therapy at 18 months. She remained off the drugs for the next 27 months with no signs of the virus in her blood.
The finding encouraged scientists hoping to find a way to save other children from a lifetime of antiretroviral treatments. A clinical trial was in the works to find out if the results could be repeated in other children.
That trial, which has yet to accrue any patients, is being carefully evaluated in light of the present findings, said Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland.
Researchers will take a close look at trial design, which calls for suspending treatment after two years, in some cases.
They may also adjust the consent forms used to inform patients about the possible risks of participating in the study, Fauci added.
Doctors do not know what caused the virus to rebound in the young girl, who was carefully monitored and tested for HIV every six to eight weeks.
There were no signs of trouble before lab results last week showed a drop in immune cells called CD4+ cells. Gay's fears were confirmed a few days later, when tests for HIV came back positive. The sequence of the virus matched that taken from the girl's mother two years earlier.
Doctors started the girl on antiretroviral medication immediately and her immune cells are recovering. She has shown no other signs of infection, such as enlarged lymph nodes.
It is also unclear where in her body the virus hid during those 27 months of negative HIV tests.
Gay noted that the doctors had not examined any tissue samples or spinal fluid from the girl, and that researchers are now discussing whether such samples may be important in future clinical studies.
