Norovirus binds to blood group A-like antigens in oyster gastrointestinal cells

To determine if histo-blood group antigens (HBGA) present in oyster gastrointestinal (GI) cells mediate accumulation of human noroviruses (NoV) in oyster GI cells. HBGA-specific monoclonal antibodies (MAbs) were used to determine the presence of the corresponding HBGA in oyster GI cells. All oyster samples tested contained type A-like HBGA in GI tissue as measured by ELISA. Recombinant Norwalk virus viral like particles (rNVLP) were bound to plates coated with oyster GI homogenate. The binding was inhibited when rNVLPs were pre-incubated with MAbs specific for type A HBGA, or samples of human saliva from type A individuals. Co-localization of rNVLP and type A-like HBGA, but not type B-like or type H-like HBGA, on GI epithelial cells was observed by immunofluorescent histochemical staining and three-channel confocal scanning laser microscopy. Type A-like HBGA is present in oyster GI cells and responsible for binding of rNVLP. This is the first report of the presence of type A-like HBGA in oyster GI cells and the specific binding of rNVLP to type A-like HBGA on oyster GI cells. The results of this study suggest that human NoV concentrate in oyster GI cells by specific binding to concentrated type A-like HBGA rather than by a nonmolecular entrapment within the tissues.