A universal RNA vaccine has been developed that is effective against any strain of the virus

Researchers at the University of California, Riverside have unveiled a new RNA-based vaccination strategy that is effective against all strains of the virus and is safe even for infants and immunocompromised people.

Each year, scientists try to predict which four flu strains will dominate the coming season. And every year, people receive an updated vaccine, hoping that scientists have correctly identified the strains.

The same situation is happening with COVID-19 vaccines, which are being adapted to combat the most common strains of the virus circulating in the United States.

This new strategy could eliminate the need to create different vaccines because it targets a part of the virus's genome that is common to all strains. The vaccine, its mechanism of action and the demonstration of its effectiveness in mice are described in an article published in the journal Proceedings of the National Academy of Sciences.

“What I want to emphasize about this vaccination strategy is its versatility,” said UCR virologist and author of the paper Zhong Hai. "It applies to many viruses, is effective against any of their variants and is safe for a wide range of people. This could be the universal vaccine we have been looking for."

Vaccines usually contain either a dead or a modified live version of the virus. The immune system recognizes the virus protein and triggers an immune response, producing T cells that attack the virus and prevent it from spreading. “Memory” B cells are also produced, training the immune system to defend against future attacks.

The new vaccine also uses a live, modified version of the virus, but does not rely on the traditional immune response or active immune proteins. This makes it safe for infants with undeveloped immune systems and people with weakened immune systems. Instead, the vaccine relies on small RNA molecules to suppress the virus.

“The host—human, mouse, or any other creature—in response to a viral infection produces small interfering RNAs (siRNAs). These RNAs suppress the virus,” explained Showei Ding, professor of microbiology at UCR and lead author of the paper. p>

Viruses cause disease because they produce proteins that block the host's RNAi response. "If we create a mutant virus that cannot produce a protein that suppresses our RNAi response, we can weaken the virus. It can replicate to a certain level, but then loses the fight against the host's RNAi response," Ding added. "This weakened virus could be used as a vaccine to boost our RNAi immune response."

When testing this strategy on the mouse Nodamura virus, the researchers used mutant mice lacking T and B cells. One injection of the vaccine protected mice from a lethal dose of the unmodified virus for at least 90 days. Research shows that nine days in the life of a mouse is roughly equivalent to one human year.

There are few vaccines suitable for infants under six months of age. However, even newborn mice produce small RNAi molecules, which explains why the vaccine protected them. The University of California, Riverside has already been granted a US patent for this RNAi vaccine technology.

In 2013, the same research group published a paper showing that influenza infections also cause us to produce RNAi molecules. "So our next step is to use this same concept to create a flu vaccine to protect babies. If we are successful, they will no longer have to depend on their mothers' antibodies," Ding said.

It's likely that their flu vaccine will be delivered in a spray form, since many people don't like needles. "Respiratory infections spread through the nose, so a spray may be a more convenient delivery system," High noted.

In addition, the researchers say it is unlikely that the virus would be able to mutate to evade this vaccination strategy. "Viruses can mutate in areas not targeted by traditional vaccines. However, we target their entire genome with thousands of small RNAs. They will not be able to escape this," High said.

Ultimately, the researchers believe they can cut and paste this strategy to create a universal vaccine for any number of viruses.

"There are several known human pathogens: dengue, SARS, COVID. They all have similar viral functions," Ding said. "This strategy should be applicable to these viruses due to the easy transfer of knowledge."