title: Attachment and localization of human norovirus and animal caliciviruses in fresh produce.
abstract: Fresh produce is a high risk food for human norovirus (NoV) contamination. To help control this pathogen in fresh produce, a better understanding of the interaction of human NoV and fresh produce needs to be established. In this study the attachment of human NoV and animal caliciviruses (murine norovirus, MNV-1; Tulane virus, TV) to fresh produce was evaluated, using both visualization and viral enumeration techniques. It was found that a human NoV GII.4 strain attached efficiently to the Romaine lettuce leaves and roots and green onion shoots, and that washing with PBS or 200 ppm of chlorine removed less than 0.4 log of viral RNA copies from the tissues. In contrast, TV and MNV-1 bound more efficiently to Romaine lettuce leaves than to the roots, and simple washing removed less than 1 log of viruses from the lettuce leaves and 1-4 log PFU of viruses from roots. Subsequently, the location of virus particles in fresh produce was visualized using a fluorescence-based Quantum Dots (Q-Dots) assay and confocal microscopy. It was found that human NoV virus-like particles (VLPs), TV, and MNV-1 associated with the surface of Romaine lettuce and were found aggregating in and around the stomata. In green onions, human NoV VLPs were found between the cells of the epidermis and cell walls of both the shoots and roots. However, TV and MNV-1 were found to be covering the surface of the epidermal cells in both the shoots and roots of green onions. Collectively, these results demonstrate that (i) washing with 200 ppm chlorine is ineffective in removing human NoV from fresh produce; and (ii) different viruses vary in their localization patterns to different varieties of fresh produce.
authors.affiliation: Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: Erin
authors.initials: E
authors.lastname: DiCaprio
authors.affiliation: Department of Food Science and Technology, College of Food, Agricultural, and Environmental Sciences, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: Anastasia
authors.initials: A
authors.lastname: Purgianto
authors.affiliation: Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: Yuanmei
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Department of Molecular Virology, Immunology, and Medical Genetics, College of Medicine, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: John
authors.initials: J
authors.lastname: Hughes
authors.affiliation: Department of Food Science and Technology, China Jiliang University, Hangzhou, Zhejiang 310018, PR China.
authors.forename: Xiangjun
authors.initials: X
authors.lastname: Dai
authors.affiliation: Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA. Electronic address: li.926@osu.edu.
authors.forename: Jianrong
authors.initials: J
authors.lastname: Li
mesh_terms: D000818:Animals; D002139:Caliciviridae / Q000187:drug effects / Q000502:physiology*; D002713:Chlorine / Q000494:pharmacology; D005506:Food Contamination / Q000032:analysis; D005511:Food Handling; D006801:Humans; D018545:Lactuca / Q000821:virology*; D051379:Mice; D029322:Norovirus / Q000187:drug effects / Q000502:physiology*; D019697:Onions / Q000821:virology*; D018515:Plant Leaves / Q000821:virology; D018517:Plant Roots / Q000821:virology
chemical_list: D002713:Chlorine
keywords: Attachment; Fresh produce; Human norovirus; Localization; Murine norovirus; Tulane virus