Assessment of the Effectiveness of a Hygroscopic Coating on the Conservation of MS2 Viability during Aerosol Sampling with MCE Filters

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

     Abstract Number: 651
     Working Group: Bioaerosols

Abstract
Membrane filters are commonly used in air sampling. However, after collection on filters, viruses are vulnerable to being inactivated due to desiccation. Though gelatin filters can conserve virus viability, they sometimes disintegrate in longer-duration air sampling or at high temperatures. Thus, an alternative method is needed. This study explored whether increasing the hygroscopicity of a membrane filter by coating it with glycerol can improve the conservation of bacteriophage MS2 viability during air sampling.

In Phase 1 of the study, mixed cellulose ester (MCE) filters (0.8 µm pore size, 37 mm diameter) were assessed at the benchtop under two conditions: as-packaged and glycerol-coated, to determine whether the glycerol detrimentally impacted the viability of MS2. In Phase 2, MCE filters were used to collect aerosolized MS2 in three configurations: as-packaged, glycerol-coated, and wetted with 0.1X PBS. A gelatin filter was also used as a reference. Glycerol was coated onto as-packaged MCE filters by soaking them in 10% glycerol (v/v with Nanopure® water) and then baking them at 100 °C for 30 minutes. To prepare the PBS-wetted filter, 200 μl of 0.1X PBS was pipetted onto an as-packaged filter. Both benchtop and aerosol exposure periods lasted 30 minutes. A Collison nebulizer was used to aerosolize MS2 in Phase 2. Extraction of MS2 from filters was done into 0.1X PBS, followed by culturing on single-layer agar and quantification by the plaque assay.

The results from Phase 1 of the study showed 76% more recovery of viable MS2 from glycerol-coated filters than as-packaged. It indicated that glycerol has no detrimental effects on MS2 viability (p=0.87 by ANOVA). For Phase 2, the experimental setup has been validated by assessing sampling ports and pumps and the aerosol collection trials are ongoing. The complete study will be presented at the conference.