Evaluation of the Effectiveness of a Hygroscopic Glycerol Coating on MCE Filters on the Conservation of MS2 Viability during Aerosol Sampling

MO WASHEEM, William Vass, Sripriya Nannu Shankar, Yuetong Zhang, Amin Shirkhani, Morteza Alipanah, Z. Hugh Fan, John Lednicky, Chang Yu Wu, University of Florida, Gainesville

     Abstract Number: 713
     Working Group: Bioaerosols

Abstract
Conservation of viable viruses collected onto membrane filters is hampered by inactivation of viruses due to desiccation during air sampling. Whether increasing the hygroscopicity of such filters can improve the viability conservation of bacteriophage MS2 during air sampling was explored in this study. First, mixed cellulose ester filters coated with a humectant (glycerol) were assessed at the benchtop scale to determine whether the glycerol detrimentally impacted the viability of MS2. The coating was accomplished by soaking as-packaged filters (APF) in 10% glycerol and baking the filters at 100 °C for 30 minutes. Averagely 121% more viable MS2 was recovered from glycerol-coated filters (GCF) than APF, indicating that glycerol has no detrimental effects on MS2 viability (p=0.031). MCE filters in three configurations - APF, GCF, and PBS-wetted filters (PWF) were then tested with aerosolized MS2 at two relative humidities (RHs), 50% and 80%, with a gelatin filter (GF) as a reference, and the GCF was preconditioned for 30 minutes at 80% RH before aerosol sampling at the same RH. The PWFs failed due to a large pressure drop. The results at the lower RH showed statistically similar (p>0.05) mean total genomic equivalence for all filter types, but the viable collection by GCF at this RH was significantly lower than other filters (p<0.05). On the other hand, at the higher RH, GCF showed 2.3 times the viable virus recovery of APF and 3.7 times that of GF (p<0.0001). Furthermore, experimental results with preconditioning of GCF and APF with moisture before aerosol exposure at 50% and 80% RH, showed GCF’s capability of viability conservation at 80% RH even without preconditioning. Thus, the moisture availability in virus aerosols at high RH (80%) was found to be the key parameter in providing an adequate amount of moisture on the filter surface to keep the collected virus viable.

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