Attachment, Uptake, Dissemination and Inactivation of Foodborne Enteric Calicviruses in Vegatables

NON-TECHNICAL SUMMARY: Our goal is to reduce the incidence of food-borne illnesses due to consumption of fruits and vegetables contaminated with human enteric viruses, particularly enteric caliciviruses such as noroviruses and sapoviruses. The risk of illness associated with consumption of raw food products can be reduced by preventing contamination, or by removing or killing the pathogenic microorganism. A better understanding of the interaction between the virus and the surface of fruits and vegetables or the internalization of virus into plants will be useful to develop new strategies to prevent contamination or to remove human viral pathogens at pre or post-harvest stages from production to consumption.
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APPROACH: We will expose vegetables (via leaves or roots) to the cell culture adapted porcine enteric calicivirus (TC/PoSaV) and HuNoV VLPs using these as surrogates for HuNoV to to determine the existence and nature of virus or VLP binding or uptake into minimally processed vegetables (lettuce). Immunofluorescence assays will be used to detect virus or VLP binding to plant surfaces. We will use cell culture infectivity and RT-PCR assays to quantitate infectious TC/PoSaV or viral RNA, respectively, within tissues of washed plants and ELISA to quantitate internalized VLPs. To determine if NoV VLP binding to lettuce is mediated by carbohydrates, similar to the known binding of NoVs to histo-blood group antigens in humans, we will first determine if related carbohydrates are present in lettuce. If present, we will use specific antibodies against such carbohydrates, or broadly reactive plant lectins that bind carbohydrates to block VLP attachment and evaluate these as potential methods to prevent NoV attachment to lettuce. Finally we will evaluate the effect of different chemical treatments to inactivate or reduce virus titers in lettuce by infectivity assays using TC/PoSaV. Inactivating agents will include chlorine bleach, hydrogen peroxide and aqueous/gaseous ozone.