HIV Vaccine: ‘We’ve just passed a milestone’

Will we ever be able to protect ourselves from HIV? For ten years, the eminent immunology professor Yves Levy, former head of Inserm, has been trying to develop a preventive vaccine. As this Thursday marks World AIDS Day and 4,900 people have been diagnosed with HIV in France in 2020, the director of the Vaccine Research Institute (VRI) and co-founder of the biotech company LinKinVax tells us about his latest “promising” results.

You are using brand new technology. What is it about ?

Professor Yves Levy. Given the complexity of HIV, we thought we had to deal with it differently. In recent years, we have studied in detail how this works. To counter this, precise targeting of dendritic cells is key. When a vaccine is introduced into the body, whether it be an inactivated virus or its fragments, it is they who send orders to the immune system. Warned, he will then make a weapon to defend himself. It may take time for the message to reach them. So our injection sends information directly to them through a kind of rocket, an antibody that targets a receptor on the surface of these cells to which we have attached the virus fragments. They are activated immediately!

Where are they?

You have them everywhere, in the skin, bronchi, mucous membranes, digestive tract … Dendritic cells patrol the entire body and are able to capture, first of all, microbes that enter the body. At this time, they present them to the immune system, which will react. If one day HIV tries to infect the cells, the body will be ready to fight it because it has retained the memory.

What do your test results show?

For prophylaxis, we administered three doses to 72 non-risk volunteers in France and Switzerland, whom we followed up for a year. After eight years of research, we have succeeded in phase 1-2, which shows that our vaccine is well tolerated and produces an interesting immune response. It’s huge! We have just passed a decisive stage. But the big unknown remains: the body certainly reacts, but will its defenses really protect it when it is infected with HIV? We don’t know yet. This requires a third phase of testing with risk groups: sex workers, gay men, women in Africa.

If this protection works, when will this vaccine be available?

This depends on the results of the Phase 3 trials to be carried out. We won’t have them for two or three years. We are also developing this technology against other viruses. Each time we keep the missile system but change the virus fragments we want to target, in other words we modify the cartridge, the weapon stays the same. Thus, trials of two vaccines against Covid, another against papillomavirus-associated throat cancer, will begin in 2023. So far, we’ve made the most progress with HIV.

Failures have been linked for 40 years. Why is it so difficult to develop an antidote?

Finding an HIV vaccine is a real challenge! If our strategy proved ineffective, we ourselves would have worked for ten years in vain. It’s not a virus like the others. In general, the germ multiplies in your body, the antibodies block it, and it is eventually destroyed, as is the case with the flu. Everything is different there, HIV infects you, then penetrates, in a few hours, into your chromosomes! You keep it. It then mutates at full speed, much faster than SARS-CoV-2. It also evades the immune system. Finally, he attacks her! But you know, forty years of research is not that long in the history of medicine. A vaccine against tuberculosis has been sought for over a century, and against hepatitis C for fifty years.

Is your antidote the only promising candidate?

Since 2009, one phase 3 trial has shown that an experimental vaccine can reduce the risk of infection by 30%. Unfortunately, attempts to reproduce these results have not been successful. It is clear that nothing happened. There are still about 20 trials at an early stage in the world, including ours. Our feature is that the strategy is completely innovative. This is a new hope.