With access to the right medication, HIV is no longer a death sentence. Since the beginning of the pandemic, researchers and pharmaceutical companies have been developing anti-retroviral drugs (ARVs) which, while not a cure, are pivotal in keeping viral count low and CD4+ cells high. CD4+ cells are the white blood cells that the virus destroys, and which keep the immune system fighting. If taken appropriately, the drugs can delay the onset of AIDS long enough for someone infected with HIV to die of old age.
On Friday November 26, Professor Matthias Gottë from McGill’s Department of Immunology and Microbiology gave a lecture on HIV drug resistance as part of World AIDS Week. He highlighted the major problems with ARV treatments: “We have really potent drug regiments available, but, still, we have the problems of drug resistance and non-adherence,” he said.
Drug resistance results from HIV mutations that occur frequently during HIV replication. Although most mutations don’t effect the resistance of HIV to drugs, mutations leading to drug resistant HIV do exist and they are problematic. “Normally, these resistant viruses are compromised, but, in the presence of drugs, the resistant virus outgrows the others,” he said.
With proper drug intake though, the virus rarely has the opportunity to mutate.
Non-adherence – the term for patients’ failure to take drugs on schedule – aggravates the problem of drug resistance. According to Dr. Chesney from the AIDS Research Institute at the University of California, an ARV regiment must be taken at least 95 per cent of the time to effectively prevent the virus from replicating at an uncontrollable rate. Drug non-adherence leads to increased viral replication, which, according to Gottë, causes increased mutations and drug resistance.
“If there is ongoing replication [of HIV], then there is eventually the occurrence of resistant viruses,” he said.
Preventing HIV drug resistance is very difficult, especially in countries where access to ARVs is limited and monitoring of drug adherence is virtually impossible. To make matters worse, a successful drug treatment is usually a cocktail of three or more ARVs. These have to be taken at specific times of the day and under certain dietary restrictions. Furthermore, the drugs have numerous side effects.
Very recently, pharmaceutical companies have engineered a one-a-day pill that contains three separate ARVs. This novel idea is a step forward to fight HIV in developing countries, but much more needs to be done. In North America, we have access to many drugs and are privileged with cutting-edge technology that enables doctors to sequence HIV in a patient. This way, doctors can check for mutations in the virus and prescribe effective treatment. But despite this headway in ARV research at home, the developing world is barely benefiting.