A man hangs red ribbons, symbols of the fight against AIDS, on December 1, in Gijon, Spain. – Mercedes Menendez/Pacific Press/Shutterstock/SIPA
- Several laboratories have announced encouraging results for obtaining a vaccine against Covid-19 and vaccination campaigns are already launching in some countries, a little less than a year after the emergence of Covid-19.
- This speed surprises several Internet users, who wonder about the fact that, conversely, there is no vaccine against HIV yet.
- The nature of HIV makes it difficult to find a vaccine, remind three experts at 20 Minutes.
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British received the first injections on Tuesday vaccine from Pfizer and BioNTech against
Covid-19, less than a year after the first report of a case of this new coronavirus by China.
A speed that alerts some Internet users, who compare research a vaccine against Covid-19 to that against HIV. “AIDS […] 40 years old, 0 vaccine ”,“ Covid […] 10 months, 9 vaccines ”, we can read on a visual massively relayed on social networks.
Is this comparison relevant? Why is finding an HIV vaccine more difficult than finding a coronavirus vaccine? 20 Minutes put the question to three experts.
FAKE OFF
Comparison between the two viruses is difficult because their nature and action are very different. Unlike Sars Cov-2, which causes Covid-19, HIV, which causes AIDS, mutates a lot and has many subtypes. “HIV is one of the most variable viruses, along with hepatitis C,” says Constance Delaugerre, professor of virology at Saint-Louis University of Paris and former head of the scientific and medical committee of Sidaction.
Because of these mutations, the traditional vaccination strategy, namely inoculating a virus to react the immune defenses of the human body, is very complicated. It involves putting a particle of the virus into the vaccine, whereas people infected with HIV will never encounter this particle because of its rate of mutation.
“This variability [du VIH] is incredible, notes the specialist. The virus defends itself against pressure when it enters the body. Immune defenses are put in place, but he spends his time countering this and changing his entire genome, in particular the envelope. And that does not prevent it from replicating and diffusing in the population. ”Knowing that the virus mutates within an infected person, but also between people.
Conversely, “coronaviruses are viruses that are much more stable, much larger, and cannot change without costing them,” says Constance Delauguerre. We had seen it with the other coronas, Sars-Cov1 and Mers, these are viruses that are less mutagenic. “
Not the same protection mechanisms
Another major difference between HIV and Sars Cov-2: the body’s protective mechanism. “For Sars-Cov2, we know, and we learned it fairly quickly, that when we produce antibodies that neutralize the infection, it protects. […] Neutralizing antibodies are very effective and are produced by most people who get infected. These are called the correlates of protection. “
“For HIV, thirty years later, we still do not know the correlates of protection well, because we have no model,” adds Constance Delaugerre. Impossible, in fact, to have one in the absence of healing. “HIV infection is not cleared at all by our immune system. Infected people carry the virus for life, ”adds Serawit Bruck-Landais, director of the quality and health research unit at Sidaction.
The last obstacle to overcome, HIV infects immune cells. However, vaccination stimulates the immune response. This response must therefore be stimulated without increasing the number of cells that HIV will be able to infect.
Two major avenues of research
HIV vaccine research is focused on two avenues, the antibody response and the cellular response. An ongoing trial uses neutralizing antibodies, details Serawit Bruck-Landais: “A very small portion of people living with HIV develop antibodies that allow them to live with the virus without eliminating it, but without taking treatment. no more. We have been able to isolate these antibodies and produce them in quantity. Now the tests consist of injecting them. “
Researchers are exploring other avenues to avoid contamination. One option is to ‘donate monoclonal antibodies [ “des molécules naturellement produites par le système immunitaire en vue de déclencher une attaque ciblée sur un danger déjà rencontré”, selon l’institut Curie] to a child ”, when it is breastfed, explains Morgane Bomsel, research director at CNRS and head of a laboratory at the Cochin Institute. This track is “very useful when we want to block the infection in a very short time. “
“Huge Technological Advances” Thanks to HIV Research
The researcher underlines that “the enormous amount of energy and research” undertaken on the vaccination against the HIV “made that one learned a lot of things in immunology, applicable to other pathologies”. She also cites “huge technological advances”. “The money invested has not been lost. “
Almost 78 million people have been infected by HIV since the start of the epidemic, according to the UN.
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