A step toward diagnosing the flu with your tongue

Flu season is fast approaching in the northern hemisphere. And a taste-based influenza test could someday have you swapping nasal swabs for chewing gum. A new molecular sensor has been designed to release a thyme flavor when it encounters the influenza virus.

Researchers reporting in ACS Central Science say that they plan to incorporate this type of low-tech sensor into gum or lozenges to increase at-home screenings and potentially prevent pre-symptomatic transmission of the disease.

Staying home is critical to preventing the spread of infectious diseases like influenza; however, people with the flu are contagious before they develop symptoms. Current flu diagnostics like nasal swab-based PCR tests are accurate, but they are slow and expensive. At-home lateral flow tests, akin to those used to test for COVID-19, are convenient and generally low-cost, but don’t catch pre-symptomatic infections.

As written in their published study, Lorenz Meinel and colleagues address these flu detection shortcomings “by switching away from complex detectors and machinery and toward a detector that is available for anyone, everywhere and anytime: the tongue.”

The team developed a molecular sensor that releases a flavor that human tongues can detect—thymol, found in the spice thyme. The sensor is based on a substrate of the influenza virus glycoprotein called neuraminidase (the “N” in H1N1).

Influenza viruses use neuraminidase to break certain bonds on the host’s cell to infect it. So, the researchers synthesized a neuraminidase substrate and attached a thymol molecule to it. Thymol registers as a strong herbal taste on the tongue. Theoretically, when the synthesized sensor is in the mouth of someone infected with the flu, the viruses lob off the thymol molecules, and their flavor is detected by the tongue.

After developing their molecular sensor, the researchers conducted lab tests with it. In vials with human saliva from people diagnosed with the flu, the sensor released free thymol within 30 minutes. When they tested the sensor on human and mouse cells, it didn’t change the cells’ functioning.

Next, Meinel and team hope to start human clinical trials in about two years to confirm the sensor’s thymol taste sensations in people with pre- and post-symptomatic influenza.

If incorporated into chewing gums or lozenges, “this sensor could be a rapid and accessible first-line screening tool to help protect people in high-risk environments,” says Meinel.

The authors have registered a patent with the European Patent Office on this technology.