Gao Xiang, Esseili Malak A, Lu Zhongyan, Saif Linda J, Wang Qiuhong
Food Animal Health Research Program, Ohio Agricultural Research and Development Center, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, Ohio, USAFDA Center for Food Safety and Applied Nutrition.
Food Animal Health Research Program, Ohio Agricultural Research and Development Center, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, Ohio, USAFDA Center for Food Safety and Applied Nutrition
Appl Environ Microbiol. 2016 May 2;82(10):2966-74. doi: 10.1128/AEM.04096-15. Print 2016 May 15.
Human norovirus (HuNoV) genogroup II genotype 4 (GII.4) strains account for about 80% of the gastroenteritis outbreaks in the United States. Contaminated food is a major transmission vehicle for this virus. In humans, pigs, and oysters, histo-blood group antigens (HBGAs) act as attachment factors for HuNoVs. In lettuce, although the virus-like particles (VLPs) of a GII.4 HuNoV were found to bind to cell wall carbohydrates, the exact binding site has not been investigated. Here, we show the presence of HBGA-like carbohydrates in the cell wall of lettuce. The digestion of lettuce leaves with cell wall-degrading enzymes exposed more binding sites and significantly increased the level of binding of GII.4 HuNoV VLPs. Competition assays showed that both the HBGA monoclonal antibody, recognizing the H type, and plant lectins, recognizing α-l-fucose in the H type, effectively inhibited VLP binding to lettuce tissues. Lettuce cell wall components were isolated and their NoV VLP binding characteristics were tested by enzyme-linked immunosorbent assays. The binding was inhibited by pretreatment of the lettuce cell wall materials with α-1,2-fucosidase. Collectively, our results indicate that H-type HBGA-like carbohydrates exist in lettuce tissues and that GII.4 HuNoV VLPs can bind the exposed fucose moiety, possibly in the hemicellulose component of the cell wall.
Salad crops and fruits are increasingly recognized as vehicles for human norovirus (HuNoV) transmission. A recent study showed that HuNoVs specifically bind to the carbohydrates of the lettuce cell wall. Histo-blood group antigens (HBGAs) are carbohydrates and are known as the attachment factors for HuNoV infection in humans. In this study, we show the presence of HBGA-like carbohydrates in lettuce, to which HuNoVs specifically bind. These results suggest that specifically bound HuNoVs cannot be removed by simple washing, which may allow viral transmission to consumers. Our findings provide new information needed for developing potential inhibitors to block binding and prevent contamination.
人诺如病毒（HuNoV）基因II型4基因型（GII.4）毒株在美国约80%的肠胃炎暴发中占主导。受污染的食物是该病毒的主要传播载体。在人类、猪和牡蛎中，组织血型抗原（HBGA）作为HuNoV的附着因子。在生菜中，虽然发现一株GII.4 HuNoV的病毒样颗粒（VLP）可与细胞壁碳水化合物结合，但具体的结合位点尚未研究。在此，我们展示了生菜细胞壁中存在类HBGA碳水化合物。用细胞壁降解酶消化生菜叶可暴露出更多结合位点，并显著增加GII.4 HuNoV VLP的结合水平。竞争试验表明，识别H型的HBGA单克隆抗体和识别H型中α-L-岩藻糖的植物凝集素均能有效抑制VLP与生菜组织的结合。分离出生菜细胞壁成分，并通过酶联免疫吸附试验检测其与诺如病毒VLP的结合特性。用α-1,2-岩藻糖苷酶预处理生菜细胞壁材料可抑制这种结合。总体而言，我们的结果表明生菜组织中存在H型类HBGA碳水化合物，且GII.4 HuNoV VLP可结合暴露的岩藻糖部分，可能是在细胞壁的半纤维素成分中。
沙拉作物和水果越来越被认为是人类诺如病毒（HuNoV）传播的载体。最近一项研究表明，HuNoV可特异性结合生菜细胞壁的碳水化合物。组织血型抗原（HBGA）是碳水化合物，是已知的人类HuNoV感染的附着因子。在本研究中，我们展示了生菜中存在类HBGA碳水化合物，HuNoV可与之特异性结合。这些结果表明，简单清洗无法去除特异性结合的HuNoV，这可能导致病毒传播给消费者。我们的发现为开发潜在抑制剂以阻断结合并防止污染提供了所需的新信息。
