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Moderna will begin testing its investigational mRNA-based HIV vaccine as early as tomorrow (August 19), according to a new submission to the U.S. National Institutes of Health Clinical Trials Register.
The Phase 1 trial would involve 56 healthy adults between the ages of 18 and 50 who do not have HIV, and will test the vaccine’s safety as well as look for a baseline immune response. The vaccine candidate is functionally similar to the mRNA system that has been so successful in Moderna’s COVID-19 vaccine.
For years, researchers have studied the potential of mRNA vaccines, but Pfizer and Moderna COVID-19 vaccines are the first to be used in humans, and both have been shown to be safe and widely effective in preventing and reducing the severity of SARS. -CoV-2 infection.
Moderna will test two versions of its new vaccine candidate, officially called mRNA-1644 (the variant is known as mRNA-1644v2-Core). It is the first mRNA vaccine against HIV to be tested in humans.
There will be four groups in the trial – two receiving a mixture of versions of the vaccine and two receiving one or the other.
At this early stage, the trial is not “blind”, which means anyone who receives the vaccine will know what they are getting. This is because researchers are not currently trying to determine the effectiveness of the vaccine. This first phase will last around 10 months, and they just want to make sure it’s safe and triggers a basic immune response.
If the vaccine passes this phase, they will still have to go through phase 2 and phase 3 trials to determine how well they work in preventing HIV infection in the general population.
So how do mRNA vaccines work? Unlike traditional vaccines, which usually contain part of a weakened or inactivated virus, mRNA vaccines contain an “instruction book” which is passed on to our cells and tells them how to make specific protein fragments that are found inside. outside of the target virus.
For a short time (usually 24 to 48 hours), our cells start making these proteins and our body marks them as foreign and triggers an immune response. Hopefully this means that when you are exposed to the real virus your body will recognize the spike proteins and be quick enough to fight it off before the infection gets too severe.
According to Moderna’s clinical trial submission on its HIV vaccine candidate: “The hypothesis is that sequential vaccination with a primer targeting the germline followed by directional booster immunogens can induce specific classes of B-cell responses. and guide their early maturation to a largely neutralizing antibody (bnAb) via an mRNA platform. “
It’s a bit wordy, but stimulating these largely neutralizing antibodies (bnAbs) is important when it comes to HIV.
We are already very good at using antivirals to treat HIV and reduce the risk of an exposed person becoming infected.
But making a vaccine against the virus has proven difficult due to how quickly it infects our DNA and is able to easily mutate its structure.
The most promising approach we have is to stimulate these largely neutralizing antibodies, which some people naturally develop against HIV, but which we have not been able to trigger with a vaccine so far.
However, an mRNA approach can be different. Earlier this year, research from the International AIDS Vaccine Initiative and Scripps Research tested a component of the mRNA vaccine candidate – the immunogen – but using a system without mRNA.
While the vaccine candidate did not generate the necessary complete immune response, 97 percent of participants developed the desired immune response – early stimulation of B cells.
“We and others postulated many years ago that in order to induce bnAbs, you have to start the process by triggering the right B cells – cells that have special properties giving them the potential to develop into cells that secrete bnAb, “said immunologist William Schief who led the Scripps Research team in February.
“In this assay, the cells targeted were only about one in a million of all naive B cells. To get the right antibody response, we must first prime the right B cells. The data from this assay confirms the ability of the vaccine’s immunogen to do that. “
This same immunogen will now be used in this new assay in conjunction with Moderna’s mRNA system, which has been so useful against SARS-CoV-2.
The hope is that the combination will result in neutralizing antibodies largely able to fight HIV infection in the first place – and may also be effective against a range of other viruses in the future, such as the ‘next pandemic. “. The new trial is being conducted in partnership with the Bill and Melinda Gates Foundation.
In an announcement to shareholders in April, Moderna said it is also developing another HIV vaccine candidate in addition to mRNA-1644, called mRNA-1574. And mRNA vaccines are also being studied to prevent various other viruses, such as herpes simplex virus and influenza.
As the COVID-19 pandemic continues to rage around the world, it is promising that some of the technologies we have developed to combat it could also help us prevent other devastating viruses in the future.
You can read more about Moderna’s Phase 1 trial here.
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