Comparisons of a Novel Air Sampling Filter Material, Wash Buffers and Extraction Methods in the Detection and Quantification of Influenza Virus

Abstract

Quantification of aerosolized influenza virus is used for determining inhalation exposure. Several bioaerosol samplers and analytical methods have been used; however, the detection and quantification of influenza virus among aerosol samples remains challenging. Therefore, improved viral aerosol measurement methods are needed. This study evaluated influenza virus recovery among three filter types polytetrafluoroethylene, polyvinylchloride and polystyrene. Polytetrafluoroethylene, polyvinylchloride are fabricated filter materials and commonly used in the scientific literature to sample for viral aerosols. A novel, electrospun polystyrene filter material may improve viral aerosol recovery during filter-based air sampling. The filter materials were compared across the following conditions: treated with or without air, filter wash buffer (HBSS or PBS), and viral RNA extraction method (QIAamp Viral RNA Mini Kit or Trizol). Twenty trials were completed in a chamber and samples were analyzed using RT-qPCR. Viral recovery was significantly different (p-value < .0001) by filter type. Polystyrene filter use resulted in recovery of the most viral RNA. Air sampling did not affect the recovery of viral RNA from the filter materials (p-values > 0.05). Viral RNA concentrations were significantly different across extraction methods for all comparisons (p-values < 0.05). Our results demonstrated that the novel polystyrene filter material resulted in the highest concentration of extracted RNA compared to the commonly used polytetrafluoroethylene and polyvinylchloride, which we speculate may be related to the chemical composition of the filter material (e.g., polystyrene is an aromatic hydrocarbon whereas polytetrafluoroethylene and polyvinylchloride contain more polar, and thus potentially reactive, carbon-halogen bonds). Air sampling did not have an effect on viral RNA recovery. Using Hanks Balanced Salt Solution with QIAamp Viral RNA Mini Kit, and Phosphate-buffered saline with the Trizol extraction, resulted in the most viral RNA recovery.