Characterization of Functional Components in Bovine Colostrum That Inhibit Norovirus Capsid Protruding Domains Interacting with HBGA Ligands

Human noroviruses (huNoVs) cause epidemic acute gastroenteritis with significant mortality and morbidity worldwide. However, there are no commercial vaccines or antivirals against these important pathogens so far. In this study, we found that bovine colostrum (bCM) inhibited huNoV VLPs and their capsid-protruding (P) domains binding to histo-blood group antigens (HBGAs) that are huNoV receptor or attachment factors for infection, suggesting that bCM may function as a natural antiviral against huNoVs. We then characterized the bCM for the functional inhibition components by sequentially separating bCM into multiple fractions through various chromatography approaches, followed by determining their inhibitory abilities against huNoV receptor-binding P protein interacting with HBGAs. The protein components of bCM functional fractions were examined by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Our data suggested that some milk proteins, likely in the form of glycoproteins, contribute to the observed blocking effects of bCM. Our findings lay an important foundation to further develop bCM into a potential natural antiviral against huNoVs.