Research Makes Flu Virus Visible to Naked Eye

Researchers have discovered a way to make influenza visible to the naked eye by engineering fluorescent dye molecules to target a specific enzyme of the virus. The team was able to develop a prototype test kit that detects influenza in samples using a handheld lamp or blue laser pointer, and that even helps determine if a given antiviral therapy will likely be effective.

The scientists, from University of Notre Dame, created a new method to detect neuraminidase, which is located on the surface of the virus. They began by designing a dye molecule to emit red fluorescent light when it interacts with the neuraminidase. They then used test samples that mimicked that of an infected patient, and spiked the samples with neuraminidase that had been purified from the virus. Emission of red fluorescent light from a sample is a positive indication of the influenza virus, blue signals a negative result.


While still a prototype, with optimization the diagnostic could potentially be developed for use in point-of-care clinics or the home environment for a rapid, easy to interpret test for the presence of influenza.

The same process also allowed them to determine which of two approved antiviral drugs would be a better treatment option for the individual patient.

Following validation of enzyme recognition, the team tested the dye with two antiviral drugs used to treat influenza (Zanamivir, also known as Relenza, and Oseltamivir, known widely as Tamiflu). Both antivirals are neuraminidase inhibitors. Antiviral drug was added to samples containing dye and neuraminidase. Upon illumination, red fluorescence indicated the enzyme was still active, whereas blue indicated the drug failed to inhibit the enzyme. For patient samples, blue fluorescence would indicate the neuraminidase activity had been blocked, presenting an effective treatment option.

“Viral cultures are the gold standard for diagnosis of influenza but take several days to develop. By targeting an enzyme inherent to the virus and identifying its presence in a sample, we can make a rapid determination of the influenza in a patient for an efficient and immediate diagnostic that would improve patient treatment and reduce overuse of antivirals,” said study leader Bradley Smith, professor at Notre Dame.

The study, by Liu W et al, was published April 20, 2017, in the Journal of the American Chemical Society.