A few days ago, news was spreading far and wide that a baby born with HIV was functionally cured of the disease. Essentially, it means that while tiny bits of the HIV were found in the blood, none is able to replicate itself. While this news is definitely a cause worthy of celebration, we shouldn’t be so quick to assume that a cure for HIV/AIDS is on the horizon. In fact, this news does not give any indication as to our first functional AIDS cure, as there have been other documented cases in the past of children overcoming HIV. To understand why, allow me to explain how the HIV virus works.
As many of you may already know, the reason why HIV, or Human immunodeficiency Virus, is so debilitating is due to the fact that it attacks a person’s immune system. Once the HIV virus brings down the immune cell count low enough, patients develop AIDS, or Acquired Immunodeficiency Syndrome. So in the end, it’s not the HIV itself that actually kills the person; death is actually caused by any number of diseases that attack the body while the immune system is compromised by the HIV. In addition, the reason why HIV is so difficult to cure is due to its extremely rapid rate of mutation. Much like bacteria that can mutate to become resistant to penicillin, the HIV virus can mutate to develop resistances to any number of anti-viral treatments – at a much higher rate of resistance than bacteria at that. In other words, a combination of immune system suppression as well as high rates of mutation makes HIV one of the deadly diseases in the world.
How do you fight HIV?
HIV is not just any virus; it is a retrovirus. A standard virus, such one that causes the common cold, contains DNA encapsulated by a protein shell. This DNA is then injected into a host cell, where the virus’ DNA will be incorporated into the DNA of said cell and begin to replicate itself (or stay dormant only to activate after certain triggers such as stress, as with the case with herpes). In a retrovirus, on the other hand, the virus stores its genetic information in the form of RNA, a variant of DNA. However, since RNA cannot be incorporated into a host cell’s DNA, it must first make a DNA copy of itself before doing so. The transcription from RNA to DNA is extremely inaccurate (relatively speaking), which allows for an extremely high rate of mutation in the virus’ genetic material. In addition, there is an average of one mutation per generation per virus particle. Once HIV or any retrovirus takes over a host cell, millions of new HIV particles are created, and each particle is capable of another mutation once another host cell is infected. This translates to multiple variants of HIV forming every day. Of course, many of the mutations will cause the virus to die, but since the replication rate is so high, only a few viable particles are needed to keep the ball going.
Life Cycle of HIV; Copyright 2004, University of Washington
Treatments generally target an enzyme called reverse transcriptase, which transcripts RNA to DNA. When these antriretroviral drugs are taken as prescribed, it is somewhat effective at keeping HIV at bay, although it will never completely eradicate it. However, due to the high toxicity of these drugs, many people may “forget” to take a dose or two, at which point the HIV is given a chance to rebound or mutate to a drug-resistant strain. If a drug-resistant strain is developed, prognosis is generally very poor thereafter. In addition, if the treatment were to ever cease, the HIV will most certainly rebound after staying in a dormant state within a host cell’s DNA, much like the way herpes and HPV works. There are no ways to rid a cell of foreign DNA, which is why treatments must continue throughout the lifetime of a patient.
So then how was this baby cured of HIV?
There is no cure or vaccine for HIV. As vaccines generally work on the principle that a person’s immune system will create a defense specific to the disease, HIV’s high mutation rate makes it almost impossible for an effective HIV vaccine to be created. In addition, even if a vaccine were to be created, people may still have to take monthly vaccinations for it to be effective, much like the way the flu virus has a different vaccination every year (and even then, about 30% of people who get the vaccine still get the flu in the end). So then how was this child cured of HIV when there is no known cure, let alone a vaccine? The answer is not quite so simple, and scientists still don’t know, but there are some theories being thrown about.
The most convincing theory thus far suggests that the timing of and dosage of the antiretroviral drugs were critical in curing the baby of HIV. Normally, when a mother with HIV is pregnant, as soon as the baby is born, only one or two drugs are given to the newborn as a preventive measure in case the baby is HIV positive. Then only after tests confirm the presence of HIV in the newborn does full treatment begin. What happened in the case with this child is slightly different. Instead of giving only one or two drugs to the baby, the doctor began full treatment with three different drugs before even finding out the results of the HIV test. Within a month after birth, the viral load in the baby’s blood was undetectable. This suggests that the drugs were able to fight back the HIV before it had a chance to establish a reservoir within the baby. Left unchecked, viral loads can increase exponentially within a person’s body, but since the virus never really had a chance to get a foothold in the first place, the drugs and the newborn’s own immune system were able to fight back and defeat it.
On the flip side, you must keep in mind that this was technically only a “functional” cure. Further tests using more sophisticated methods showed that the baby did still have trace amounts of viral DNA in the blood. Fortunately, none of this genetic material is capable of replication.
HIV/AIDS mortality rate throughout the world. HIV treatments are extremely expensive, so the highest mortality rate from HIV/AIDS comes from poorer countries.
Now, after being off the antiretroviral drugs for over a year, there are still no signs of a functioning virus in the baby. Doctors are now suggesting that babies may have a different immune system from adults. While nothing is certain yet, this news is definitely indicative of new treatments for babies who are infected by HIV during pregnancy or during birth. Current statistics show that only 23% of HIV positive babies are able to receive treatment with most of the untreated babies concentrated in Africa. In addition, regular antiretroviral treatment is extremely expensive, and simply not an option for poorer families. With this new development, simply preventing HIV from taking hold of a newborn’s immune system by preemptively delivering high dosages of antiretroviral drugs is definitely much more cost effective than a lifetime worth of treatment. So even though there is no definitive evidence of a potential cure for HIV, this is definitely a step in the right direction and may lead to more breakthroughs in the future.