HIV: Moderna vaccin?

Numé / Marcus Dupont-Besnard

The pandemic linked to the Covid-19 disease has put a spotlight on vaccines based on the technique of messenger RNA (mRNA). This has been in development for several decades now, and was already described as a source of hope in the fight against certain diseases. Among them, HIV – the AIDS virus. As it turns out, Moderna, which is responsible for one of the current leading vaccines against covid, is about to launch a human clinical trial for its vaccine against HIV, the virus that causes AIDS.

The goal of all vaccines is the same: to allow the development of « memory » immune cells, and therefore to train the body to respond to an infectious agent. Often this is done by recovering the genetic sequence of the « attacking » protein of the virus concerned, and combining it with an inactivated or attenuated infectious agent.

In doing so, the immune system learns to recognize and fight the virus without posing any danger. But the body is deceived: it believes in a real infection, and it fights it. So he will be ready for the real virus, if it presents itself later.

The mRNA technique is innovative and involves biotechnology: it is the same principle as for any vaccine, except that it is the cells of the vaccinated person which themselves produce the proteins against which the body must learn to to defend oneself. Messenger RNA then simply serves as a « recipe »: cells are provided with the source code of proteins so that they can produce them. This technique has no impact on the genome of the person vaccinated – there is absolutely no risk of altering the DNA, they are two separate things.

This clinical trial will be the first in humans for Moderna’s HIV vaccine. This is a phase 1 study, involving a small sample of patients – 58 people, aged 18 to 50 years. The aim is to assess the safety of the vaccine – that it does not cause unexpected or dangerous side effects; as well as its immunogenicity – that it does trigger an effective immune response with the production of long-lasting protective antibodies. The HIV virus is quite different from the SARS-CoV-2 coronavirus. Advances against covid have been rapid, as it is a genus of virus relatively understood by scientists, and of course also thanks to the unprecedented lifting of logistical and financial obstacles to the development of vaccines targeting it. On the other hand, it has been notoriously difficult to develop an effective vaccine against AIDS during all these decades. In question, the HIV virus is very difficult to target: as it cannot replicate itself, it penetrates into cells, into their chromosomes, taking control of its machinery which it uses for its viral replication.

Anyway, it will take a few more years to hope for a vaccine against HIV, the virus that causes AIDS. The scientific challenge is immense, but the research is clearly on the right track. And it may be that research conducted in the context of the Covid-19 pandemic, thanks to obstacles being lifted at unprecedented speed, is helping these kinds of advances.