Monday March 4 2013
Antiretrovirals work by slowing the spread of HIV
Global news coverage has been dominated by the potentially groundbreaking news that a child born with HIV appears to have been ‘cured’ of the infection.
The Guardian reports that US doctors have made medical history with a ‘first functional cure’ of an unnamed two-year-old girl born infected with HIV and ‘who now needs no medication’. BBC News quotes researcher Dr Deborah Persaud, who presented the news to a medical conference, as saying, “This is a proof of concept that HIV can be potentially curable in infants”.
The researchers report that the baby was started on antiretroviral (anti-HIV) treatment at two days of age and continued on this to 18 months. By one month old, HIV could no longer be detected in the baby’s blood using standard laboratory tests, and the virus continued to be undetectable up to 26 months of age. However, highly sensitive laboratory tests could still detect the presence of HIV at very low levels.
This means that scientists have not found a complete cure for HIV. However, as The Guardian clarifies, they have found a ‘functional cure’, in which the girl is still infected, but currently requires no treatment. This means the disease is less likely to progress in the girl, potentially giving her a good life expectancy.
It is not yet possible to say whether this child’s viral levels will remain low, or whether she will need further antiretroviral therapy.
These findings therefore do not mean that a complete cure for HIV has been discovered.
What have the scientists discovered about HIV treatment?
It is now unusual for babies to be born with HIV in developed countries due to advances in treatment and care. These advances mean it is usually possible to prevent an HIV-infected mother from passing the infection on to her baby. However, infant HIV remains a signfiicant problem in many developing countries.
Researchers from several US medical institutions have presented the findings from a case of a 26-month-old child who was born with HIV and had anti-HIV treatment started when she was just 30 hours old. The findings were announced at the Conference on Retroviruses and Opportunistic Infections in Atlanta, US, on March 4 2013.
Dr Deborah Persaud and colleagues say the baby girl was born to a mother confirmed (apparently at a late stage) to be HIV positive. Two separate blood samples were taken from the newborn when she was two days old, confirming that she was also infected.
The baby was started on antiretroviral treatment (ART), and further blood samples were taken to test for the HIV virus when she was seven, 12 and 20 days old. These blood samples were all positive for HIV, but a further sample taken at 29 days did not detect levels of the virus. ART was continued until 18 months of age.
Standard laboratory tests could then not detect any levels of the virus in 16 further blood samples taken between one and 26 months of age. Highly sensitive laboratory tests for HIV were also performed at 24 and 26 months of age. At 24 months, these sensitive tests identified a single copy of HIV RNA in the blood, and 37 copies of HIV DNA per million of a particular type of white blood cell. However, the virus did not appear to be able to replicate itself. By 26 months, highly sensitive tests revealed only four copies of HIV DNA per million of the white blood cell.
Therefore, though the virus was still detectable with highly sensitive blood tests, the virus was undetectable with standard clinical tests, which the researchers say ‘confirms a state of functional HIV cure’. They conclude that ‘this is the first well-documented case of functional cure in an HIV positive child and suggests that very early ART may prevent establishment of a latent reservoir and achieve a cure in children’.
What is antiretroviral therapy?
HIV is treated with a combination of antiretroviral (anti-HIV) drugs, known as ‘ART’. These drugs are not a ‘cure’ for HIV, doctors give them to patients with HIV to try and stop the virus replicating and to reduce the levels of virus. Reducing the amount of viruses in a person’s body can help limit the harm done to the body’s immune system by HIV.
Doctors measure the success of ART treatment by how much it reduces the viral load (the number of particles of HIV present in a volume of blood) to levels that can no longer be detected by standard blood tests (‘undetectable levels’). Doctors hope that by using ART treatment, they can prolong life and reduce the risk of disease progression and associated complications. A person with HIV normally has to continue on ART for the rest of their life to prevent viral levels from increasing again.
However, as was demonstrated in the case of this young child, even if the HIV is at undetectable levels, it doesn’t mean the virus has completely gone. It can still be detected on highly sensitive tests. For this reason, the researchers in the current study were careful to call this a ‘functional cure’ because the virus was undetectable on standard tests but had not gone completely.
How is HIV passed from a mother to her baby?
HIV is a bloodborne virus and can be passed on through blood and other bodily fluids. If an HIV positive woman is pregnant there is a small risk of the virus being passed to the baby during pregnancy, during birth, or through breastfeeding. Doctors will make every effort to prevent HIV being transmitted from mother to baby. This is usually attempted by:
- giving the mother ART during her pregnancy
- taking special care around the time of delivery
- using formula rather than breast milk
However, if the baby is infected and starts treatment early, and treatment is taken when needed, then the outlook for the child is good.
We are still a long way short of a ‘cure’ for HIV.
The potential outcome of treatment for the baby girl in the current US case is unclear. She is likely to need further blood tests as she grows up, to keep a check on the levels of HIV in her blood. Hopefully, she will continue to grow healthily into adulthood with the virus at undetectable levels. However, it is possible that she may need further ART if her viral levels begin to rise again.
It is impossible to say how or why this particular child has achieved a ‘functional cure’. It could be the fact that she had very early treatment with ART, or it could be due to the biology of this individual child.
The next step for researchers is to see whether the ART regime used for this child causes a similar outcome for other high-risk newborns.
It is currently uncertain whether the information contained in this case report will lead to any advances in the treatment of older children or adults with HIV. ART is prescribed on an individual basis according to clinical tests, response and adverse effects. Anyone taking ART should continue to take the treatment as prescribed by their specialist.
The findings do not mean that a new complete cure for HIV has been found.
However, if the results can be replicated in other newborns, it may offer the hope of reducing the number of cases of infant HIV in the developing world.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.