The new mRNA vaccine, which has so far been tested in humans, includes several influenza strains with pandemic potential that can be transferred to humans from animals.

A new study published in the journal Science demonstrates the potential of a single mRNA vaccine to protect against all 20 known subtypes of influenza A and B. The hope is that the vaccine, which has so far been effective in preclinical animal models, will prevent future influenza pandemics. promoting immunity against strains of the virus that have yet passed from animals to humans.

Vaccines teach the immune system to recognize certain parts of a pathogen. When real danger comes, the body can quickly remember this training and fight back. Annual flu vaccines usually focus on two to four antigens of the strains most likely to be circulating at the time. Recent COVID-19 vaccines focus on just one iteration of the infamous SARS-CoV-2 protein.

One of the potential strengths of the newly emerging mRNA vaccine technology is the ability to simultaneously present a wide range of different antigens to the body. Old vaccine technology cannot pack 10 or 20 different antigens into a single dose, but mRNA technology does not face these limitations.

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Until now, with the latest booster dose of Omicron’s bivalent mRNA vaccine, researchers have included two specific antigens in one shot. But what if a single vaccine could help teach the immune system to recognize dozens of different iterations of the same virus? This is exactly the idea that researchers from the Perelman School of Medicine at the University of Pennsylvania explored in their landmark study.

The key antigenic target in influenza vaccines is the hemagglutinin protein molecule. It is on the surface of the virus and is crucial for its infectivity. Each strain of influenza carries its own hemagglutinin protein of a unique form. The experimental mRNA vaccine tested in this new study covers 20 different influenza hemagglutinins: all 18 known influenza A subtypes and two influenza B subtypes.

A recently published study reports testing a polyvalent vaccine in mice and ferrets. As explained by Scott Hensley, senior author of the new study, the main conclusion from these experiments is that the animals developed different antibodies against all 20 strains of influenza. This shows that a single mRNA vaccine can effectively provide broad protection against a large number of different antigens.

We have developed a new multivalent mRNA vaccine for all known influenza virus subtypes. Our statue showing the vaccine was invited to @ScienceMagazine. 1/n

— Hensley Lab (@SCOTTeHENSLEY) November 25, 2022

The idea of ​​the new vaccine is not to prevent influenza infection, but to reduce the severity of the disease. Initial animal studies suggest this is possible, as the vaccine effectively prevents severe disease in mice exposed to both the specific strains contained in the vaccine and other flu strains other than the specific 20 targets.

Perhaps the most unusual aspect of this vaccine is that it contains antigens from influenza strains that have not yet entered the human body. Many of the 20 antigenic targets are influenza types currently active only in animals. But according to Hensley, the main goal here is to preempt the next pandemic by creating some level of broad immunity among the population.

“[У мышей] the vaccine prevented severe illness and death from viruses that differed from the components of the vaccine,” Hensley said. “This is reminiscent of a pandemic situation. And that is our goal: to achieve a baseline level of immunity in the population that will not necessarily prevent infection with new pandemic strains, but rather prevent severe disease and death caused by them.”

This work is far from the first to explore the potential of mRNA vaccine technology to combat influenza. Low mRNA flu vaccines are in various stages of testing. A team of researchers recently demonstrated the preclinical efficacy of an mRNA vaccine that targets four specific influenza proteins and is believed to provide universal protection against most strains.

The hypothesis is that giving such a vaccine, especially to very young children, can help set up their immune memory against all subtypes of influenza for the rest of their lives.

“The idea here is to create a vaccine that gives people a baseline level of immune memory to different strains of flu so that there will be much less illness and death in the next flu pandemic,” Hensley said. “We think this vaccine can significantly reduce the chance of ever getting a severe flu infection.”

This radical new strategy unlocks the potential of mRNA technology and changes the way vaccines are used. While the preclinical trials are ongoing, the first phase of human trials is planned.

Moderna is developing mRNA vaccines for cancer, herpes and chickenpox.

Source: New Atlas