AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Performance of Cascade Impactors for Sampling Aerosolized Viruses
MICHAEL SCHUIT, Jamie Kline, Kristin Bower, Paul Dabisch, NBACC
Abstract Number: 77 Working Group: Bioaerosols: Characterization and Environmental Impact
Abstract INTRODUCTION: Many studies have been published on the effects of infection with aerosolized filoviruses in animal models to support medical countermeasure evaluation. In inhalation studies, knowledge of the particle size distribution (PSD) of an inhaled aerosol is critical since it is known to affect regional deposition in the respiratory system and potentially disease presentation. However, the PSDs of the aerosols generated in previous inhalation studies with filoviruses were not routinely measured and reported, and no studies were identified which characterized the performance of different particle sizing instruments with airborne filoviruses. Therefore, the aim of the present study was to assess the accuracy of two different cascade impactors for estimating the PSD of airborne filoviruses.
METHODS: Ebola virus stocks diluted in media and containing 100-nm fluorescent polystyrene latex beads as a non-viable tracer were aerosolized in a small test system and sampled with two different impactors – a Mercer cascade impactor and a micro orifice uniform deposit impactor (MOUDI). Viral titers were determined by microtitration and tracer concentrations determined with a fluorescence reader. The fluorescence values and virus titers for each stage were used to estimate the particle size distribution of the sampled aerosols, and the ratio of fluorescence to the viral titer was used as a measure of the relative losses in viral infectivity from stage to stage.
RESULTS AND CONCLUSIONS: For either impactor, no significant difference was observed in the particle size distribution calculated from the viral titers and fluorescence measurements and the ratio of fluorescence to viral titer did not change significantly from stage to stage, suggesting that viral infectivity was not affected by the changes in impaction velocity that occur from stage to stage. These results demonstrate the validity of the Mercer cascade impactor and the MOUDI for estimating the PSD of airborne Ebola virus in animal inhalation studies to support countermeasures development.