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Why do not we have a vaccine against HIV?



Around 37 million people around the world live with HIV, the human immunodeficiency virus. While treatments to prevent or treat HIV infection are available, there is no vaccine available. Many approaches are currently being developed, some of which are preventative for use by people at risk of developing the disease, and others aimed at removing the virus in cells.

The goal of a vaccine is to give our immune system the right weapons to defeat the virus. Unfortunately, HIV is extremely adaptable – it can change components and become unrecognizable. Because of this, many efforts to produce a vaccine have encountered limitations. The most prominent example of this was the "RV HIV study", in which the HIV infection rate had dropped by 31

.2 percent compared to placebo. The vaccine was safe and well tolerated, but unfortunately only moderately effective.

"RV144 was not a public health success, but was of great importance for scientific endeavor. Immunoassays after the study showed signals that correlated with protection or lack of protection. This laid the foundation for the development of improved approaches. Jill Gilmour, Executive Director for Human Immunology at the International AIDS Vaccine Initiative (IAVI), told IFLScience. "Coupled with new scientific insights, the pipeline is now more diverse and robust, increasing the chances of success in delivering effective vaccines and related immune-based interventions against HIV infection and AIDS."

Finding Effective Treatment Has This After being a tough fight, several approaches are now being implemented. Earlier this year, it was announced that the Phase I trial of one of these vaccines will take place in 2019. SofiaV / Shutterstock

This special vaccine targets a fusion peptide on the surface of the virus. Peptides are short chains of amino acids (the constituents of proteins), and HIV uses them to invade cells. The vaccine is designed to stop this action and prevent the virus from infecting cells. So far, it has been effective in 31 out of 40 tested HIV strains tested. Animal testing has shown that the vaccine is effective across several species and is believed to be effective in humans as well. The 2019 study evaluates side effects and safety limitations for the vaccine.

Recently, Science Advances described a different approach. In the study, the researchers injected animal models with antigens designed to stimulate the production of precursor antibodies. These will eventually evolve into bNAbs or "largely neutralizing antibodies" that bind to and envelop the virus to prevent other cells from becoming infected. IAVI recently announced that the first vaccine candidate to induce bNABs is entering the clinical trial. This is the first of its kind. There is currently a vaccine in a Phase II efficacy trial, which will run until 2022, and a Phase III trial (comparison of treatments) of RV144, which will start in 2016 and run until mid-2021 ,

"Developing an effective HIV vaccine has been challenging given the nature of the virus and its interaction with the human immune system. No one has ever naturally recovered from HIV infection, and there are no correlates that signal which immune responses are needed to block or eradicate HIV. " Gilmour. "An HIV vaccine remains an important tool to halt the spread of HIV and stop AIDS. The number of new HIV infections has barely decreased over the last five years and could increase if prevention efforts are not significantly increased. "


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