Influenza is epidemic all over the world every year, causing many deaths and financial losses.It is known that it can be treated with antiviral drugs and can be cured before the onset if it is taken before the onset of symptoms, but the existing test method, immunochromatography, requires 12 to 24 hours after the onset of symptoms. Since accurate diagnostic results cannot be obtained, there is a need for a test method that enables earlier diagnosis.

　This research group focused on the application of single-molecule digital measurement method with the aim of detecting highly sensitive viruses that can be diagnosed even in the early stages of infection when the amount of virus is small.This is to detect the virus by observing the fluorescence by reacting with a substrate that emits fluorescence by an enzyme called neuraminidase that exists on the surface of the influenza virus and one influenza virus in a small container.When a solution of influenza virus and fluorescent substrate is enclosed in a micro-container array created by microfabrication technology, one virus is stochastically confined in the micro-container.The number and concentration of viruses can be calculated by treating the signal as if it were digital data, assuming that the container that emits fluorescence is 1 and the container that does not emit fluorescence is 1.

　Comparing the detection limits of this digital influenza detection method and the immunochromatography method, it was found that the digital influenza detection method was 1,000 to 10,000 times more sensitive.In fact, we succeeded in detecting the virus from the mouthwash with a lower virus concentration than the nasal swab used in the immunochromatography method, paving the way for individual tests and pain-free tests.

　This method enables early detection of influenza virus, and is expected to suppress the aggravation and epidemic of influenza.

Paper information:[Scientific Reports] Antibody-free digital influenza virus counting based on neuraminidase activity