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Why do not we have a vaccine for HIV yet?

About 37 million people worldwide live with HIV, the human immunodeficiency virus. While treatments are available to prevent or treat…

About 37 million people worldwide live with HIV, the human immunodeficiency virus. While treatments are available to prevent or treat HIV infections, there is no vaccine for it. Many approaches are currently being developed: some are preventive to be used by people at risk of getting the disease and some aim to eradicate the virus that hides in cells.

The goal of a vaccine is to give our immune system the right weapon to defeat the virus. Unfortunately, HIV is extremely adaptable – it can change components and become unrecognizable. Because of this, many efforts have been made to produce a vaccine against restrictions. The most well-known example of this was the “RV HIV study”, which showed a reduction of HIV infection by 31

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

“RV144 was not a success for public health, but was very important for the scientific experiment. Immunoassays after the trial revealed signals correlated with protection or lack of protection, which lay the foundation for developing improved methods,” told IFLScience, Dr. Jill Gilmour, Executive Director of Human Immunology at the International AIDS Vaccine Initiative (IAVI). “Combined with new scientific discoveries, the pipeline today is more varied and robust, increasing the chances for success in achieving effective vaccines and related immune-based interventions to stop HIV infection and AIDS.”

Although the search for effective treatment has been an upward battle, several approaches will now be achieved. Earlier this year, Phase I testing of one of these vaccines was announced in 2019.

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This particular vaccine targets a fusion peptide on the surface of the virus. Peptides are short chains of amino acids (protein components) and HIV uses them to enter cells. The vaccine aims to stop this action and prevent the virus from infecting cells. So far, it has been effective over a promising 31 percent of HIV strains of 208 tested. Tests performed in animals have shown that the vaccine is effective over several species and it is believed to be effective also in humans. The 2019 study will assess adverse reactions and safety restrictions for the vaccine.

Another method has recently been reported in Science Advances. In the study, researchers injected animal models with antigens designed to stimulate the production of precursor antibodies. These will eventually develop in bNAbs, or “generally neutralizing antibodies,” which will bind to the virus and envelop it to stop it from infecting other cells. It has recently been announced by IAVI that the first vaccine candidate aimed at developing bNABs is entering clinical trials. This is the first of its kind. There is currently a vaccine in a Phase II effect study that will run until 2022 and a phase III study (RV144) comparison of RV144 that started in 2016 and will run until mid 2021.

“The development of an effective HIV vaccine has been challenging in the light of the nature of the virus and its interaction with the human immune system: no person has ever naturally recovered from an HIV infection, and there are no correlations that signal which immune responses are required to block or clear HIV, “explained Gilmour. “An HIV vaccine is still an important tool to stop the spread of HIV and end AIDS. The number of new HIV infections has hardly declined over the last 5 years and may increase if preventive efforts are not significantly scaled up.”

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