Results from a recent clinical trial suggest that the future for HIV prevention may lie in the form of a synthetic vaccine. Previous attempts to create a vaccine that protects against HIV have been unsuccessful due to the constantly changing nature of the virus’s structure. This is a roadblock as vaccines work on the basis of your immune cells recognising the virus and inciting an appropriate response to get rid of it.
Scientists at the University of Oxford have overcome this by creating a synthetic vaccine made up of 14 areas of the HIV genome that “bear fitness costs when mutated”. This means that if these areas of the genome change then it decreases the virus’s chance of survival. By attaching these regions together it increases the chance of your immune cells recognising a part of the virus and reacting to it. In the case of this vaccine, it aims to make your body produce immune cells called T cells that kill cells that are infected with HIV.
The trials participants were healthy individuals who do not have the disease. They were vaccinated 3 times at different lengths between vaccines; some were injected again within weeks, some months. The scientists took cells from the volunteers and infected them with HIV and then introduced the T cells that had been made in response to the vaccine.
The vaccine caused the production of lots of T cells that recognised HIV infected cells, and also inhibited the virus from replicating. The success of this trial has meant that there will be a second carried out, this time people who are at high risk of contracting the disease will be vaccinated in Kenya.
Scientists from Duke University in the USA have also determined the structure of a HIV envelope protein. This protein, like the 14 used in the vaccine, does not often change and the researchers are hoping it can go towards creating HIV vaccines. These vaccines would not work by stimulating T cells like the synthetic vaccine, as the discovered protein has sites that antibodies, which are produced by B cells, can bind can bind to and neutralise the virus. This research will be continued after the University received a large donation from the Bill & Melinda Gates foundation to develop a HIV vaccine.