Comparing the performance of 3 bioaerosol samplers for influenza virus

Abstract

A B S T R A C TRespiratory viral diseases can be spread when a virus-containing particle (droplet) from one individual is aerosolized and subsequently comes into either direct or indirect contact with another individual. Increasing numbers of studies are examining the occupational risk to healthcare workers due to proximity to patients. Selecting the appropriate air sampling method is a critical factor in assuring the analytical performance characteristics of a clinical study. The objective of this study was to compare the physical collection efficiency and virus collection efficiency of a 5 mL compact SKC BioSampler ® , a gelatin filter, and a glass fiber filter, in a laboratory setting. The gelatin filter and the glass fiber filter were housed in a home-made filter holder. Submersion (with vortexing and subsequent centrifugation) was used for the gelatin and glass fiber filters. Swabbing method was also tested to retrieve the viruses from the glass fiber filter. Experiments were conducted using the H1N1 influenza A virus A/Puerto Rico/8/1934 (IAV-PR8), and viral recovery was determined using culture and commercial real-time-PCR (BioFire and Xpert). An atomizer was used to aerosolize a solution of influenza virus in PBS for measurement, and two Scanning Mobility Particle Sizers were used to determine particle size distributions. The SKC BioSampler demonstrated a U-shaped physical collection efficiency, lowest for particles around 30-50 nm, and highest at 10 nm and 300-350 nm within the size range examined. The physical collection efficiency of the gelatin filter was strongly influenced by air flow and time: a stable collection across all particle sizes was only observed at 2 L/min for the 9 min sampling time, otherwise, degradation of the filter was observed. The glass fiber filter demonstrated the highest physical collection efficiency (100% for all sizes) of all tested samplers, however, its overall virus recovery efficiency fared the worst (too low to quantify). The highest viral collection efficiencies for the SKC BioSampler and gelatin filter were 5% and 1.5%, respectively. Overall, the SKC BioSampler outperformed the filters. It is important to consider the total concentration of viruses entering the sampler when interpreting the results.

Frequent recovery of influenza A but not influenza B virus RNA in aerosols in pediatric patient rooms

“…They suggested the loss of infectivity was due to desiccation or degradation, which could be improved if an enhanced infectivity detection method was incorporated 21 . Two other studies evaluated the collection efficiency of other commercially available air samplers and similarly inferred a loss of infectivity in air samples due to drying of the aerosol particles 22,23 . Despite the inability to recover infectious virus in our air samples, if for aerosol transmission the putative human infectious dose (HID) was 0.6‐3 TCID 50 and equivalent to 90‐1950 RNA copies, 4,8,24 all our PCR‐positive samples exceeded the upper bound of the HID 50 and might indicate the potential to initiate infection via the aerosol route.…”

Filtration performances of non-medical materials as candidates for manufacturing facemasks and respirators

“…The size distribution of aerosols ( ) is obtained by scanning the voltage that is applied to the DMA. Similar to a previous work ( Li et al, 2018 ), the size-dependent filtration efficiency ( ) is calculated by where and are the size distributions measured at the outlet (downstream) and inlet (upstream) of the filter holder. Based on the size distributions, we can also evaluate the overall number-based filtration efficiencies.…”

Collection, particle sizing and detection of airborne viruses

“…Fabian et al (2009) reported that Teflon and gelatin filters recovered only 22 and 10%, respectively, of infectious influenza viruses compared with the BioSampler. Li et al (2017) evaluated the performance of a 5 ml BioSampler, gelatin filter and glass fibre filter for the collection of influenza H1N1 virus, and found that deactivation of most of the trapped viruses was a result of extraction of virus off the filters. Similarly, relative extraction efficiencies attained using alumina nanofibre vs glass fibre filters were compared for MS2 phage with the BioSampler as a reference sampler by Li et al (2009); the extraction efficiency of the nanofibre filter was less than 10%, while that for the glass fibre filter varied from 32Á3% to 162%.…”

“…Li et al . () evaluated the performance of a 5 ml BioSampler, gelatin filter and glass fibre filter for the collection of influenza H1N1 virus, and found that deactivation of most of the trapped viruses was a result of extraction of virus off the filters. Similarly, relative extraction efficiencies attained using alumina nanofibre vs glass fibre filters were compared for MS2 phage with the BioSampler as a reference sampler by Li et al .…”