Inactivation of Airborne Influenza Virus in Mice Using a Photocatalytic Air Purifier

Aerosols are a major transmission route for seasonal influenza infections. Titanium dioxide (TiO2) photocatalyst has broad-spectrum antiviral activity, including in vitro influenza virus inactivation; however, whether the TiO2 photocatalyst can effectively inactivate airborne influenza A viruses in vivo under conditions that mimic natural aerosol transmission remains unclear. Here, we evaluated in vivo inactivation of airborne H1N1 seasonal influenza virus by a photocatalyst-equipped air purifier using a mouse model. Influenza virus WSN strain aerosols were sprayed in a 60 L acrylic box with a nebulizer, circulated through a photocatalyst-equipped air purifier, exposed to BALB/c mice for 40 min after circulation, and subsequently collected with an air sampler. Thirty minutes of TiO2 photocatalyst treatment reduced influenza virus infectivity by 99.97%, and significantly lowered lung viral titer in mice on day 3 post-infection. Over 14 days post-infection, mice showed no >10% weight loss, 100% survival, and disease progression to the PBS (−) aerosol group. This suggests that the photocatalyst-equipped air purifier may reduce H1N1 seasonal influenza onset, preventing viral spread.