No more chasing viral strains

US scientists have found a RNA-based vaccine strategy that is effective against any strain of a virus and can be used safely even in babies or the immunocompromised.

Every year, researchers try to predict the four influenza strains that are most likely to be prevalent in the upcoming flu season. And every year, people line up to get their updated vaccine, hoping the researchers formulated the shot correctly. 

The same is true of COVID vaccines, which have been reformulated to target sub-variants of the most prevalent strains circulating in the US. 

The new strategy would eliminate the need to create all these different shots, because it targets a part of the viral genome that is common to all strains of a virus, according to the paper published in the Proceedings of the National Academy of Sciences. 

Virologist and paper author Rong Hai from University of California Riverside said it was broadly applicable to any number of viruses, effective against any variant of a virus, and safe for a broad spectrum of people. 

Traditionally, vaccines contain either a dead or modified, live version of a virus. The body’s immune system recognizes a protein in the virus and mounts an immune response. This response produces T-cells that attack the virus and stop it from spreading. It also produces “memory” B-cells that train your immune system to protect you from future attacks. 

The new vaccine also uses a live, modified version of a virus. However, it does not rely on the vaccinated body having this traditional immune response or immune active proteins — which is the reason it can be used by babies whose immune systems are underdeveloped, or people suffering from a disease that overtaxes their immune system. Instead, this relies on small, silencing RNA molecules. 

“A host — a person, a mouse, anyone infected — will produce small interfering RNAi as an immune response to viral infection. These RNAi then knock down the virus,” said Shouwei Ding, professor of microbiology at UCR, and lead paper author. 

The reason viruses successfully cause disease is because they produce proteins that block a host’s RNAi response. “If we make a mutant virus that cannot produce the protein to suppress our RNAi, we can weaken the virus. It can replicate to some level, but then loses the battle to the host RNAi response,” Professor Ding said. “A virus weakened in this way can be used as a vaccine for boosting our RNAi immune system.” 

There are few vaccines suitable for use in babies younger than six months old. However, even newborn mice produce small RNAi molecules, which is why the vaccine protected them as well. UC Riverside has now been issued a US patent on this RNAi vaccine technology. 

In 2013, the same research team published a paper showing that flu infections also induce us to produce RNAi molecules. “That’s why our next step is to use this same concept to generate a flu vaccine, so infants can be protected. If we are successful, they’ll no longer have to depend on their mothers’ antibodies,” Professor Ding said. 

Their flu vaccine will also likely be delivered in the form of a spray, as many people have an aversion to needles. Additionally, the researchers say there is little chance of a virus mutating to avoid this vaccination strategy. They believe they can ‘cut and paste’ this strategy to make a one-and-done vaccine for any number of viruses.