Comparison of three air samplers for the collection of four nebulized respiratory viruses

Abstract Viral respiratory tract infections are a leading cause of morbidity and mortality worldwide. Unfortunately, the transmission routes and shedding kinetics of respiratory viruses remain poorly understood. Air sampling techniques to quantify infectious viruses in the air are indispensable to improve intervention strategies to control and prevent spreading of respiratory viruses. Here, the collection of infectious virus with the six-stage Andersen cascade impactor was optimized with semi-solid gelatin as collection surface. Subsequently, the collection efficiency of the cascade impactor, the SKC BioSampler, and an in-house developed electrostatic precipitator was compared. In an in-vitro setup, influenza A virus, human metapneumovirus, parainfluenza virus type 3 and respiratory syncytial virus were nebulized and the amount of collected infectious virus and viral RNA was quantified with each air sampler. Whereas only low amounts of virus were collected using the electrostatic precipitator, high amounts were collected with the BioSampler and cascade impactor. The BioSampler allowed straight-forward sampling in liquid medium, whereas the more laborious cascade impactor allowed size fractionation of virus-containing particles. Depending on the research question, either the BioSampler or the cascade impactor can be applied in laboratory and field settings, such as hospitals to gain more insight into the transmission routes of respiratory viruses. Practical Implications Respiratory viruses pose a continuous health threat, especially to vulnerable groups such as young children, immunocompromised individuals and the elderly. It is important to understand via which routes these viruses can transmit to and between individuals that are at risk. If we can determine the amount of a certain respiratory virus in the air, then this will help to predict the importance of transmission through the air for this virus. Most currently available air sampling devices have not been designed to collect infectious viruses from the air. Therefore, we here optimized and compared the performance of three air samplers for four different respiratory viruses.