Size distribution and viral RNA load of influenza virus-laden airborne particles emitted from pigs over the course of an H1N1 infection

Airborne influenza infections cause significant disease in animals and people. However, there is limited information on the dynamics of viral emissions and size distribution of airborne virus-laden particles generated by infected animals. In this study, we used pigs as a model for the airborne transmission of influenza A virus (IAV) and we quantified nasal shedding, viral RNA load of airborne particles emitted from pigs experimentally infected with a swine-origin H1N1 IAV, and characterized the size distribution of the virus-laden particles generated from infected pigs over the course of infection. We found that the peak of nasal shedding and airborne IAV-laden particles across multiple size ranges took place at 2 days post inoculation (DPI), with higher viral RNA load found in larger particles. The amount of airborne IAV emitted by infected pigs over the course of infection in particles > 8 μm was significantly higher than that in particles between 0.22 and 1.7 μm. These findings help understand the risk of airborne transmission of IAV in pigs and provide information to help control airborne infections more effectively.