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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Produce Safety and Microbiology Research » Research » Publications at this Location » Publication #261397
Title: Binding of Norwalk virus viral-like particles to veins of romaine lettuce

Author
item Gandhi, Kamal
item Mandrell, Robert
item Tian, Peng

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/18/2010
Publication Date: 12/10/2010
Citation: Gandhi, K.M., Mandrell, R.E., Tian, P. 2010. Binding of Norwalk virus viral-like particles to veins of romaine lettuce. Applied and Environmental Microbiology. 76(24):7997-8003.

Interpretive Summary: Noroviruses (NoV) annually cause millions of cases of gastrointestinal disease in the United States. NoV outbreaks have been known to occur also from common-source food-borne vehicles such as lettuce, frozen raspberries, and salad. In this study, we evaluated romaine lettuce as a potential vehicle for NoV transmission by testing the binding and distribution of NoV to the surface of romaine. Recombinant Norwalk virus viral-like particles (rNVLP) applied to the surface of romaine lettuce localized as large clusters primarily on the leaf veins. An extract of romaine lettuce leaves in PBS (RE) bound rNVLP particles in a dose-dependent manner. RE did not bind rNVLP by histo-blood group antigens (HBGA), nor was RE competitive with rNVLP binding to porcine gastric mucin. These results suggested that non-HBGA molecules in RE bind rNVLP by a binding site(s) different from the defined binding pocket on the virion. Extracts from cilantro, iceberg lettuce, spinach, and celery also bound rNVLP. Samples of each of the vegetables spiked with rNVLP and tested with anti-NVLP antibody revealed by confocal microscopy the presence of rNVLP only on the veins of cilantro, but throughout the surface of iceberg lettuce.

Technical Abstract: Noroviruses (NoV) annually cause millions of cases of gastrointestinal disease in the United States. NoV are associated with raw shellfish outbreaks, particularly oysters, which are thought to bioaccumulate NoV particles during the filter feeding process. NoV outbreaks, however, have been known to occur also from other common-source food-borne vehicles such as lettuce, frozen raspberries, and salad. In this study, we evaluated romaine lettuce as a potential vehicle for NoV transmission by testing the binding and distribution of NoV to the surface of romaine. Recombinant Norwalk virus viral-like particles (rNVLP) applied to the surface of romaine lettuce localized as large clusters primarily on the leaf veins. An extract of romaine lettuce leaves in PBS (RE) bound rNVLP particles in a dose-dependent manner. RE did not bind rNVLP by histo-blood group antigens (HBGA), nor was RE competitive with rNVLP binding to porcine gastric mucin. These results suggested that non-HBGA molecules in RE bind rNVLP by a binding site(s) different from the defined binding pocket on the virion. Extracts from cilantro, iceberg lettuce, spinach, and celery also bound rNVLP. Samples of each of the vegetables spiked with rNVLP and tested with anti-NVLP antibody revealed by confocal microscopy the presence of rNVLP only on the veins of cilantro, but throughout the surface of iceberg lettuce.