title: Postharvest Survival of Porcine Sapovirus, a Human Norovirus Surrogate, on Phytopathogen-Infected Leafy Greens.
abstract: Leafy greens are increasingly being recognized as an important vehicle for human noroviruses (HuNoV), which cause recurring gastroenteritis outbreaks. Leafy greens often become infected by phytopathogens in the field, which may cause symptoms on the edible parts. Whether plant pathogen infections enhance the survival of HuNoV on leafy greens is unknown. Lettuce and spinach plants were infected with a bacterium, Xanthomonas campestris pv. vitians strain 701a, and with Cucumber mosaic virus strain Fny, respectively. The survival rate of porcine sapovirus (SaV), a HuNoV surrogate, on infected and noninfected postharvest leaves was then assessed. In addition, acibenzolar-S-methyl, a commercial chemical elicitor of plant systemic defense, was used to assess whether stimulating the plant host defense affects the postharvest survival of SaV. Leaves harvested from control and treated plants were inoculated with SaV and incubated for 7 days at 4°C. The infectivity (tissue culture infectious dose affecting 50% of the culture [TCID50]/ml) and RNA (genomic equivalent/ml) titers of SaV were assayed using immunohistochemistry staining and SaV-specific TaqMan real-time reverse transcription PCR. Our results showed that cucumber mosaic virus Fny induced mild, nonnecrotic symptoms on spinach leaves and had no effect on SaV survival. In contrast, X. campestris pv. vitians 701a induced small localized necrotic lesions and significantly enhanced SaV survival on lettuce leaves. Treatment with acibenzolar-S-methyl was effective in reducing X. campestris pv. vitians 701a-induced lesions on infected lettuce plants but had no direct effect on SaV survival when used on healthy lettuce plants. These findings indicate that phytopathogen-induced necrotic lesions may enhance the postharvest survival of HuNoV on lettuce leaves. Therefore, preventive measures aiming to maintain healthy plants and minimize preharvest biological damage are expected to improve the safety of leafy greens.
authors.affiliation: Food Animal Health Research Program, Department of Veterinary Preventive Medicine, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio 44691, USA.
authors.forename: Malak A
authors.initials: MA
authors.lastname: Esseili
authors.affiliation: The Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio 44691, USA.
authors.forename: Ashlina
authors.initials: A
authors.lastname: Chin
authors.affiliation: Food Animal Health Research Program, Department of Veterinary Preventive Medicine, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio 44691, USA.
authors.forename: Linda
authors.initials: L
authors.lastname: Saif
authors.affiliation: The Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio 44691, USA.
authors.forename: Sally A
authors.initials: SA
authors.lastname: Miller
authors.affiliation: The Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio 44691, USA.
authors.forename: Feng
authors.initials: F
authors.lastname: Qu
authors.affiliation: The Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio 44691, USA; The Department of Plant Pathology and Crop Physiology, Louisiana State University AgCenter, Baton Rouge, Louisiana 70803, USA. MIvey@agcenter.lsu.edu.
authors.forename: Melanie L
authors.initials: ML
authors.lastname: Lewis Ivey
authors.affiliation: Food Animal Health Research Program, Department of Veterinary Preventive Medicine, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio 44691, USA. wang.655@osu.edu.
authors.forename: Qiuhong
authors.initials: Q
authors.lastname: Wang
mesh_terms: D000818:Animals; D017250:Caliciviridae Infections / Q000821:virology; D017799:Cucumovirus; D059022:Food Safety; D005759:Gastroenteritis / Q000821:virology; D006801:Humans; D018545:Lactuca / Q000382:microbiology; D029322:Norovirus; D010935:Plant Diseases / Q000382:microbiology / Q000821:virology; D018515:Plant Leaves / Q000382:microbiology / Q000821:virology*; D060888:Real-Time Polymerase Chain Reaction; D029341:Sapovirus / Q000235:genetics / Q000502:physiology*; D018724:Spinacia oleracea / Q000382:microbiology; D013552:Swine / Q000821:virology*; D016959:Xanthomonas campestris