Sampler-Induced Loss of Respiratory Virus Infectivity Revealed by Spiked Collection-Liquid Experiments

Abstract

Understanding the transmission risk of respiratory viruses in indoor environments requires reliable detection of infectious particles in air samples. However, mechanical stress during air sampling may reduce the survival of infectious virus, complicating accurate assessment. This study investigated the impact of air sampler-induced mechanical stress on the RNA recovery and infectivity of rhinovirus, SARS-CoV-2 and influenza A virus using the Coriolis μ liquid impinger in an experimental setting with spiked collection liquids rather than aerosol or ambient air collection. Collection liquids were spiked with known virus concentrations and subjected to different airflow rates. Infectious virus titres and viral RNA copies were quantified by culture and PCR, respectively. Results demonstrated substantial reductions in culturable virus for SARS-CoV-2 and influenza A virus (up to 98.6% loss) at the tested airflow speeds, whereas rhinovirus changes were minimal and of limited biological significance. Viral RNA concentrations remained mostly unchanged throughout all airflow speeds for SARS-CoV-2 and rhinovirus, but were reduced for influenza A virus. These findings suggest that mechanical stress caused by an air sampling device can significantly decrease the recovery of infectious viruses, which could lead to underestimation of the presence of infectious virus. Our results emphasise the need to account for virus-specific stability and sampler-induced inactivation when interpreting data from air sampling studies and assessing airborne transmission risk.