The teen is among a very small number of HIV-infected people in the world who have remained free of active infection for a number of years without continuous treatment with antiretroviral drugs.
The unidentified girl was infected at the time of her birth in 1996 because of transmission from her mother, whose HIV was poorly controlled, said Dr. Asier Saez-Cirion of the Pasteur Institute in Paris.
"So the girl received a prophylactic treatment from the day she was born," Saez-Cirion said in an interview from Vancouver, where he is attending the 8th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention.
The infant was kept on that drug regimen — standard therapy for children at risk of being infected — for six weeks, after which "her viral load went up to very high levels," he said.
At three months of age, doctors put the girl on antiretroviral drugs, which stop HIV from replicating in the cells and eventually destroying the immune system and progressing to AIDS.
She remained on those medications until about age five-and-a-half, when her family stopped bringing her to the clinic where she was being treated. Saez-Cirion said it's not known why the family halted the girl's treatment.
The child returned to the clinic after being off antiretrovirals for a full year and doctors were surprised to find there were no signs of HIV in her blood.
"The viral load, despite no treatment given, remained undetectable at the time," he said.
"So it was decided that no treatment was going to be (given), but the girl was going to be closely monitored.
"This girl has been able to maintain virus control for 12 years now. So for 12 years, she has been in remission from infection."
Commenting on the case, Francoise Barre-Sinoussi, the Nobel Prize-winning co-discoverer of the human immunodeficiency virus, said the teenager is "doing perfectly well off treatment."
"This case is clearly additional evidence of the powerful benefit of starting treatment as soon as possible, very early on."
Saez-Cirion said the French teen represents the longest period a child has gone without treatment with no detectable HIV levels in the blood, although testing has shown she does harbour HIV DNA in her cells — what's known as a reservoir of the virus.
"They are at low levels, but the virus is still there," he said.
However, she is not the longest so-called HIV controller. One patient within a group of 14 adults known as the Visconti cohort has now gone 13 years without antiretroviral treatment, Saez-Cirion said.
The Visconti patients (an acronym for Virological and Immunological Studies in CONtrollers after Treatment Interruption) are a group of 14 HIV-positive patients in France who have been able to stop taking drugs without any resurgence of the virus in their bodies. They had been on the medications for at least three years, but then stopped.
"We believe that early treatment is one reason" why the teenager has remained free of active infection," said Saez-Cirion.
"But we know that this is not enough because children that had the same kind of early treatment, they have not been able to control it once the medication is interrupted."
That was the case with the "Mississippi baby," who was born to an HIV-positive mother who had not received any treatment during pregnancy. Doctors began treating the newborn when 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.
But in July 2014, tests showed the virus had rebounded in the girl when she was almost four years old.
The case of the French teen suggests that immediate treatment may lead to remission in some children infected through their HIV-positive mothers, but other factors may be at play, such as an individual's genetic predisposition or a robust immune system.
"However, another thing that needs to be perfectly clear is that this girl is not cured," stressed Saez-Cirion.
"The virus is still there, but her remission means that she hasn't needed treatment for many years.
"But we don't know whether she will need it in the future."
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