Researchers Develop New Dental Floss Needle-Free Flu Vaccine

In a proof-of-concept study, researchers at Texas Tech University successfully vaccinated mice against influenza (flu) by cleaning their teeth with dental floss coated with inactive flu viruses. According to the researchers, this type of vaccine could potentially be deployed in “resource-limited settings with minimal training,” which could be especially helpful in active outbreaks when vaccine coverage needs to be boosted quickly.

Previous studies have shown that vaccinations delivered in the cheek or under the tongue trigger satisfactory immune responses. But it can be difficult to deliver adequate doses of these vaccines through mucosal tissues in the mouth — the lining that acts as a barrier between our body and the environment. These researchers found a solution to this: the junctional epithelium (JE) found on the tissue between teeth, at the spot where the tooth’s surface meets the gum line. By secreting different molecules, the JE detects and defends against pathogens that try to get in through the gums. And, the JE’s ability to allow molecules through and to stimulate an immune response made it a potential candidate for a vaccine site.

To test their hypothesis, they set up a flossing schedule to expose 50 mice to an inactive flu virus. One group of mice had their teeth flossed with the virus-coated floss three times, with two weeks between each dose. Then, a month after their final dose, they were exposed to an active flu virus. All survived, while a comparison group of mice that was left unvaccinated all died.

Further testing found that the mice that had been vaccinated via the floss had a strong immune response, producing ample antibodies and many immune cells. This immune defense was found throughout the body — known as systemic immunity — and in their saliva and feces. “The floss-based vaccination induced both systemic and mucosal immunity, while conventional intramuscular shots largely stimulate systemic immunity,” said first study author Rohan Ingrole, a chemical engineer at Texas Tech University. “Mucosal immunity is important because most of the pathogens enter through the mucosal routes.”

Next, the researchers wanted to know if flossing could transfer compounds to the JE in humans. As an early test, they used a fluorescent marker and blue food coloring to coat a dental pick and had healthy volunteers floss their teeth with it. Photographs confirmed that a fair amount of the dye was transferred to the space between their teeth and gum, though just over 41 percent was left on the floss.

The next step, the researchers said, is to translate the research to larger animals, which “can then lay the foundation for human testing in the near future,” said senior study author Harvinder Gill, a bioengineer at North Carolina State University.