Highly pathogenic avian influenza virus is inactivated by photocatalyst — Results from the University of Tokyo

A research group led by Project Professor Yoko Aida from the Graduate School of Agricultural and Life Sciences at the University of Tokyo, in collaboration with California Institute of Technology and the University of Miyazaki, has demonstrated that titanium dioxide-type photocatalysts can inactivate highly pathogenic avian influenza virus (HPAIV) in liquids and can also inactivate seasonal influenza viruses in aerosols. Their findings were published in Catalysts.

In recent years, HPAIV has caused extensive damage. While the primary transmission route is believed to be through contact with wild birds and other wildlife, infection through contaminated drinking water and airborne viruses in dust and aerosols is also suspected. Furthermore, reports of HPAIV infections in humans and cattle have made this a major public health concern.

The research group applied highly pathogenic avian influenza virus and seasonal influenza virus droplets to 3 -centimeter-square titanium dioxide-type photocatalyst glass sheets and activated them with 405-nanometer visible light, demonstrating that HPAIV and seasonal influenza viruses in liquid could be inactivated by 90.7% and 94.4% respectively within one hour. They also revealed that the inactivation mechanism involves damage to viral membranes, viral RNA damage, and degradation of HA (hemagglutinin) proteins on the viral particle surface.

To apply this discovery in real-world settings, the researchers verified the inactivation of viruses in aerosols using seasonal influenza virus as a surrogate virus. They sprayed 2 milliliters of seasonal influenza virus at a concentration of 2×10⁸ PFU/mL using a nebulizer in a 60-liter acrylic box, treated it for five minutes using a spot-type air purifier equipped with photocatalyst, and then recovered the virus using an air sampler.

When viral titers of the recovered virus were determined by plaque assay, the photocatalyst-treated group showed an 80.1% reduction in titer compared with the untreated group. This is the first demonstration in the world showing that devices using titanium dioxide-type photocatalyst technology can inactivate seasonal influenza virus in aerosols. Since the photocatalyst inactivates HPAIV in the same manner as seasonal influenza virus, it is expected that the photocatalyst can also inactivate HPAIV in aerosols.

Journal Information
Publication: Catalysts
Title: TiO₂ Photocatalyst Inactivates Highly Pathogenic Avian Influenza Virus and H1N1 Seasonal Influenza Virus via Multi-Antiviral Effects
DOI: 10.3390/catal16020168