Biological Collection Efficiency of a Condensation-Based Bioaerosol Sampler
MOHAMMAD WASHEEM, Amin Shirkhani, William B. Vass, Sripriya Nannu Shankar, Nohhyeon Kwak, Jiayu Li, Z. Hugh Fan, John Lednicky, Arantzazu Eiguren-Fernandez, Chang-Yu Wu, University of Miami
Abstract Number: 78
Working Group: Bioaerosols
Abstract
The biological collection efficiency (BCE) of bioaerosol samplers is crucial for accurate assessment of viable airborne pathogen threats. Condensation based aerosol samplers like Biospot-VIVAS (Viable Virus Aerosol Sampler) demonstrate >95% physical collection efficiency (PCE) for particles sized 10 nm to 10 µm and conserve viable viruses. However, the BCE of the VIVAS remains unknown. Determination of BCE is complex due to factors causing viability losses between aerosol generation and sample collection, leading to uncertainty about viable virus concentrations at the sampler inlet, which can bias results. We connected two identical VIVAS systems in series to address this issue. This arrangement allowed the determination of inlet concentrations of viable viruses, and by comparing them, we ascertained the VIVAS’ BCE. MS2 bacteriophage was aerosolized using a Collison nebulizer and collected with the VIVAS systems over varied sampling durations and inlet concentrations. Particle size distributions were monitored using a Scanning Mobility Particle Sizer. The virus collected by the samplers was quantified by plaque assay and RT-qPCR. The PCE measured during the aerosolization of 0.5 µm polystyrene latex (PSL) particles exhibited a quadratic relationship to inlet particle concentration in which the PCE decreases with increased particle concentration. The plaque assay results for BCE indicated that VIVAS was 99.2% biologically efficient across sampling durations of 10, 20, and 30 minutes without statistically significant difference (p > 0.05) when the inlet concentration was held at 5×104±1×104 particles/cm3. When particle concentrations were held between 5×104 and 5×105 particles/cm3, the BCE was 98%. At particle concentrations >106 particles/cm3, the BCE fell to 90%. It indicates BCE of VIVAS also depends on particle concentration as PCE, but it does not drop as much at high concentration. This information will be useful for calibrating other bioaerosol samplers against VIVAS.