Comparative Analysis of Two Biological Warfare Air Samplers Using Live Surrogate Agents

The United States Air Force has several high-volume biological air samplers, including the XMX/2L-MIL and the Biocapture 650. Limited information is available on either in terms of its collection of viruses and bacteria. However, previous research on the XMX/2L-MIL has determined that modifications to the secondary flow rate and the use of a virus preserving collection media may provide improved virus collection rates. In this thesis, these modifications were investigated to determine their impact on the collection of viral and bacterial aerosols. Additionally, relative collection rates were compared against those for the Biocapture 650. MS2 bacteriophage was the viral surrogate and Bacillus thuringensis kurstaki the bacterial surrogate. Aerosolized particles were released into a wind tunnel where three samplers each were exposed simultaneously. Samples were analyzed using plaque assay, cell culture on growth media, and real-time polymerase chain reaction (RT-PCR). Viability issues made it difficult to discern the impact of virus preserving media. Results showed that secondary flow rate reduction provided a statistically lower collection of viable bacteria compared to the standard secondary flow rate. The Biocapture 650 generally performed on par or better than the XMX/2L-MIL in collection of both bacterial and viral aerosols. However, longer sampling periods with the Biocapture 650 for viruses resulted in statistically inferior results