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VARIOUS ATTACHMENT AND RECOVERY OF MS2 FROM THE CONTACT SURFACES OF GLASS AND POLYMERS
Title
VARIOUS ATTACHMENT AND RECOVERY OF MS2 FROM THE CONTACT SURFACES OF GLASS AND POLYMERS
Creator
Yan, Runan
Date
2018, 2018-05
Description
Human enteric viruses are recognized as a primary etiology for foodborne diseases in the United States. Enteric viruses are highly contagious...
Show moreHuman enteric viruses are recognized as a primary etiology for foodborne diseases in the United States. Enteric viruses are highly contagious and easily transmitted via the interaction (attachment or adhesion) with biotic or abiotic surfaces followed by extended survival and then transferred to food during food preparation. Containers and tools for handling foods are commonly manufactured of polymers. These abiotic surfaces could serve as vehicles for potential viral transmission to foods. The research objective is to evaluate factors that potentially affect virus adhesion to substrate surfaces thus altering viral disease transmission, including (i) variables of the food-contact materials (e.g., polymers and glass), and (ii) finish of food-contact surfaces (e.g., smooth or rough). The virus recovery comparison by infectivity, and the surface topography by atomic force microscopy (AFM) and profiler were employed in this study. The food-contact materials used in this study include lab-made high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), and commercial polyvinyl chloride (PVC) and two types of glass. Smooth polymer sheets were made by injection molding; and some were abraded with sand paper to produce rough surfaces. Coliphage MS2 suspension, as the inoculum, was completely air-dried first on substrate surfaces, and then cold-stored for 24 hrs at 4 °C to allow sufficient contact time between viruses and surface before the viruses were eluted and recovered. Two elution protocols were developed to accommodate different sizes of the substrates, with similar virus elution efficiency confirmed. Viruses in eluates were quantified by double agar layer plaque assay. Potential alterations in virus recovery from a substrate after surfactant sodium dodecyl sulfate (SDS) pre-treatment were also tested. Via AFM measurement, smooth substrate surfaces exhibited overall uniform nanoscale profiles, with average RMS approximately ranging from 0.4 to 4.4 nm. Rough surfaces were characterized by a profiler due to greater roughness than the upper measurement limitation of AFM (2 μm). Pinholes with an approximate average 21 nm in diameter were found in cover glass, which probably contributed to significantly lower virus recoveries (32 ± 6%, averaged from 5 trials, n = 18) than that from bottom glass (48 ± 9%, averaged from 9 trials, n = 26) where no holes were observed. For smooth polymer surfaces, the greatest virus recovery was from PP with an average of 76 ± 12% (n = 14), followed by HDPE (54 ± 6%, n = 20) and LDPE (53 ± 6%, n = 7). Interestingly, virus recoveries were always significantly lower from the corresponding rough surfaces (p < 0.001), indicating rough substrate topography could potentially serve as reservoirs for viruses. By pre-treating a thin layer of SDS at various concentrations to mask the substrate surface hydrophobicity, the virus recovery from PVC surface increased by up to 21%. These data potentially assist in selecting appropriate food-contact materials and how to construct the contact surfaces in order to eliminate similar size-foodborne viruses being trapped or retained on food-contact surfaces during cleaning or intentional removal, and thus prevent foodborne viral disease transmission.
M.S. in Food Safety and Technology, May 2018
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