almost 40 years later, still no vaccines. why is it so hard?

Vaccines against COVID-19 developed in 10 months, but nothing, in almost 40 years, against HIV … Since 1983, the year of the discovery of the AIDS virus by Françoise Barré-Sinousi and Luc Montagnier, we still do not see the shadow of an effective vaccine against this virus.

Why ? How to explain these different speeds and successes? It is not a question of means, according to Jean-Christophe Goffard, director of the internal medicine department of the Erasme hospital: “There are a lot of financial resources that have been injected into this research, but also at a time when molecular biology was much less advanced than today.“

So ? Are we dealing with a particularly harsh virus?

It changes constantly

HIV has an incredible ability to mutate, far greater than that of the flu virus. It is a chameleon virus and this multifaceted aspect represents a huge difficulty in creating a vaccine. “Unlike the coronavirus, which is also an RNA virus, HIV multiplies all the time“says Dr. Goffard.”The outward appearance and the antibodies that neutralize it are not effective or are effective for such a short period of time that HIV escapes this immune response“.

Stéphane Dewit heads the infectious disease department of the CHU Saint-Pierre. When he compares HIV to the coronavirus, he has this familiar metaphor: “Coronavirus, when replicating, is very meticulous. He’s creating new viruses that look like their dad. He is not distracted, he applies himself and therefore changes very little. HIV is zozo. He is a wanderer, not at all conscientious, not at all attentive. It produces many viruses which are completely what we call “defective”, ie they will gradually enter the virus population but with more and more mutants.“.

An immune virus

HIV is not a virus that can be compared to a coronavirus. It is a virus that lives in a specific place: our immune system. It is not limited to introducing an antigen into cells and thus replicating. It targets very specific cells and is able to protect itself from the immune defenses.

Finally, last but not least, HIV has a typical envelope, consisting of sugars and proteins. It creates very strong armor that prevents antibodies from attacking it.

Trojan horse

HIV then uses the immune cells, the dendritic cells, to penetrate the mucous membranes: it rapidly colonizes the lymphocytes it infects. It only takes 24 hours to invest all the immune tissue. It manages to remain “on standby”, quiet, sheltered.

Also, because it attacks the immune system, when you stimulate an immune response against it with a vaccine, it can have the opposite effect: increasing the number of cells that can be infected with the virus. As Dr. Goffard explains, “en By activating the immune system to react against a given virus, we also increase the number of target cells for this virus, in the case of HIV. And in one clinical study that turned out to be negative, we even increased the risk of vaccine infection because there were too many activated cells. “

So far it is checkmate. None of the HIV1 vaccine candidates produced immunity in clinical trials. I

The latest disappointment

The most recent promising process was abandoned in February 2020: it was the baptized process Travel started in 2016 in South Africa, a region much more at risk than the world average.

It aimed to test the only candidate vaccines that offered partial protection against HIV in an earlier study in Thailand in 2009. The latter (Thai study) revealed that this vaccine schedule was safe and induced high antibody responses. (Efficiency 31%).

But during the trial in South Africa, no protective immune response was detected in the vaccinated group, even after 18 long months. Worse still, 129 HIV infections were diagnosed in the vaccinated patient group.

Fear of the COVID vaccine, hope for an HIV vaccine?

How to explain that the various vaccines developed against the coronavirus arouse so many fears, in a part of the population, but that for HIV we always talk about “hope”? This question has no universal answer. But that of Jean-Christophe Goffart is interesting: “For HIV, we think about our pleasure, our emotional and sexual life, the fulfillment we can have. For the coronavirus we think about protecting vulnerable people who have nothing to do with us.“

A form of response with which you will agree or not, but which will have the merit of making us reflect on the reasons for our fears.