AIDS vaccine: encouraging results despite obstacles posed by HIV

Will the vaccine protecting against the AIDS virus soon be within our reach? Researchers reported on Saturday, July 7, 2018 an encouraging progress, with an experimental vaccine that elicited an immune response in humans and protected macaques from infection. Published in the journal The Lancet these results represent a " important step ", according to the director of the study, the virologist Dan Barouch, who however warned that he There was no guarantee that the following tests would be so positive. For decades, the search for the HIV vaccine has faced particular and complex obstacles.

A "robust" immune response in nearly 400 patients, and two-thirds of immunized macaques

The study focused on 393 healthy, HIV-negative adults aged 18-50 were followed in East Africa, South Africa, Thailand and the United States between February and October 2015. Some received one of the vaccine combinations possible or a placebo, via four injections in 48 weeks. These combinations were made of different types of HIV viruses, rendered sufficiently harmless, with the hope of provoking an immune response. But this one was " robust ", praised Pr. Barouch. The tests also showed the safety of the product. Only five participants reported adverse effects, such as abdominal pain, diarrhea, dizziness or back pain. In a separate study, these same vaccines offered protection to 67% of the 72 macaques to which the researchers subsequently attempted to inoculate the virus.

Next step: a full-scale trial with key results

The results of the Next step, a full-scale trial of 2,600 women in southern Africa called Imbokodo (rock, in Zulu), are expected in 2021 or 2022. Results " impatiently awaited " by Professor Barouch, as they will determine " whether or not this vaccine will protect humans against HIV infection ". " I can not repeat enough how much we need a vaccine ," said Francois Venter of the University of the Witwatersrand (South Africa) to AFP. But " we already knew that, promising experimental vaccines that did not materialize ". For Frenchman Jean-Daniel Lelièvre, Vaccine Research Institute (AFP) interviewed by AFP: " This is probably not the definitive vaccine, but it can be a phenomenal advance ". According to him, " in the best case ", this research will produce a vaccine administrable in " almost 10 years ."

HIV Vaccine: Challenges " unprecedented "

" This will be only the fifth concept of HIV vaccine whose effectiveness will be tested in the 35 years and a few history of the epidemic ", a- he stressed. In the 35 years of the HIV epidemic, only four HIV vaccine concepts have been tested in humans, and only one demonstrated efficacy in 2009. Called RV144, it had shown that it reduced , 2% the risk of infection among 16,000 volunteers in Thailand. An effect considered too weak to pass the vaccine to a common use. Previous vaccines, however, were generally limited to region-specific versions of HIV. In this new study, the vaccines tested are called "mosaics", that is, they take pieces of different HIV viruses and combine them to trigger immune responses against a wide variety of strains. About his own results, Professor Barouch comments in a statement from The Lancet : " These results must be interpreted with caution.The challenges in the development of an HIV vaccine are without previous, and the ability to induce HIV-specific immune responses does not necessarily indicate that a vaccine will protect humans from HIV infection . "

COMPLEX VACCINE . According to Professor Barouch and his team, there are three main scientific obstacles to developing an HIV vaccine. The first is " extensive genetic diversity of the virus ", since the HIV genome can vary by 20% within the same strain, and by 35% between two strains. Then, his " rapid establishment of latent viral reservoirs " is also a major problem. The virus is hidden in areas of the body that are called " sanctuaries " and in which the immune system is powerless. Last obstacle, the lack of " immune correlates of the protection ", that is to say that one does not know how to define model of immune response able to fight against the virus.

With AFP