Search

Human norovirus (huNoV) and hepatitis A virus (HAV) have been involved in several produce-associated outbreaks and identified as major food-borne viral etiologies. In this study, the survival of huNoV surrogates (murine norovirus [MNV] and Tulane virus [TV]) and HAV was investigated on alfalfa seeds during storage and postgermination. Alfalfa seeds were inoculated with MNV, TV, or HAV with titers of 6.46±0.06 log PFU/g, 3.87±0.38 log PFU/g, or 7.01±0.07 log 50% tissue culture infectious doses (TCID50)/g, respectively. Inoculated seeds were stored for up to 50 days at 22°C and sampled during that storage period on days 0, 2, 5, 10, and 15. Following storage, virus presence was monitored over a 1-week germination period. Viruses remained infectious after 50 days, with titers of 1.61±0.19 log PFU/g, 0.85±0.21 log PFU/g, and 3.43±0.21 log TCID50/g for MNV, TV, and HAV, respectively. HAV demonstrated greater persistence than MNV and TV, without a statistically significant reduction over 20 days (<1 log TCID50/g); however, relatively high levels of genomic copies of all viruses persisted over the testing time period. Low titers of viruses were found on sprouts and were located in all tissues as well as in sprout-spent water sampled on days 1, 3, and 6 following seed planting. Results revealed the persistence of viruses in seeds for a prolonged period of time, and perhaps of greater importance these data suggest the ease of which virus may transfer from seeds to sprouts and spent water during germination. These findings highlight the importance of sanitation and prevention procedures before and during germination. [ABSTRACT FROM AUTHOR]

Human noroviruses are the leading cause of foodborne gastroenteritis in the United States. Recent research has focused on norovirus attachment to host-cell carbohydrates. This area of research increases understanding of the first step of norovirus replication in host cells; it also has been extended to explaining norovirus capsid structure and virus evolution, as well as norovirus attachment to foods and has been used in developing methods of detecting human noroviruses. This article provides a review of research conducted on human norovirus attachment, specifically on the attachment of noroviruses on foods, including original research addressing the role of spinach and green onions in disease caused by human norovirus and a common human norovirus surrogate, murine norovirus. The objective of this study is to assess the applicability of an ELISA attachment assay to predict infectivity of a genogroup II human norovirus and to determine if spinach and green onion homogenates interfere with the attachment of the virus to the carbohydrate coating. Attachment assay results for heat-treated human norovirus indicated decreasing attachment with increasing heat treatment, which likely correlates with loss of infectivity. Additionally, the presence of spinach and green onion homogenate did not affect attachment of human norovirus or murine norovirus to porcine gastric mucin. [ABSTRACT FROM AUTHOR]