Persistence of human norovirus surrogates in irrigation water systems in the Mid-Atlantic
Date
2018
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Publisher
University of Delaware
Abstract
Human norovirus (HuNoV) has been implicated as the leading cause of foodborne illness worldwide. Its ability to survive in water environments has significant implications in food safety as agriculture and processing water may be a vehicle of transmission for the virus. This research focused on the persistence and infectivity of the HuNoV surrogate viruses, murine norovirus (MNV) and tulane virus (TV) over prolonged periods in four model water systems. These surrogates were employed since HuNoV cannot be currently propagated in culture. Vegetable processing water (VW), brackish tidal surface water (SW), municipal reclaimed water (RW), and pond water (PW) were inoculated with each virus and stored at 16°C for 100 days to mimic growing conditions in the mid-Atlantic. Samples were then assayed for the presence of viral genomes using reverse transcriptase coupled with quantitative polymerase chain reaction (RT-qPCR) as a measure of likely intact phage particles. Virus samples were shown to remain infectious using the Tissue Culture Infectious Dose for 50% of the cells (TCID50) culture assay, and the presence of intact viral capsids enclosing viral genomes was determined by an RNAse assay coupled with RT-qPCR. Both MNV and TV persisted in each water type over the 100-day trial. TV was shown to have slightly greater persistence across water types as compared to MNV while both viruses were shown to persist in larger numbers in brackish tidal surface waters as compared to the other water types tested. Furthermore, virus particles were shown to remain intact and infective over the 100-day trial. The information gathered in this study highlights the need to fill in research gaps surrounding human norovirus and its persistence in agriculture water systems.