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Bovine κ-casein inhibits human rotavirus (HRV) infection via direct binding of glycans to HRV

  • Inagaki, M.
  • Muranishi, H.
  • Yamada, K.
  • Kakehi, K.
  • Uchida, K.
  • Suzuki, T.
  • Yabe, T.
  • Nakagomi, T.
  • Nakagomi, O.
  • Kanamaru, Y.1, 2, 3, 4, 5
  • 1 United Graduate School of Agricultural Science
  • 2 Faculty of Applied Biological Sciences
  • 3 Faculty of Pharmaceutical Science
  • 4 Central R&D Laboratory
  • 5 Department of Molecular Microbiology and Immunology
Published Article
Journal of Dairy Science
American Dairy Science Association
Publication Date
Jan 01, 2014
Accepted Date
Jan 17, 2014
DOI: 10.3168/jds.2013-7792


Human rotavirus (HRV) is a major etiologic agent of severe infantile gastroenteritis. κ-Casein (κ-CN) from both human and bovine mature milk has been reported to have anti-HRV activity; however, the mechanism of this activity is poorly understood. The present study examined the molecular basis for the protective effect of bovine κ-CN derived from late colostrum (6–7 d after parturition) and from mature milk. Among the components of casein, κ-CN is the only glycosylated protein that has been identified. Therefore, we investigated whether the glycan residues in κ-CN were involved in the anti-HRV activity. Desialylated CN obtained by neuraminidase treatment exhibited anti-HRV activity, whereas deglycosylated CN obtained by o-glycosidase treatment lacked antiviral activity, indicating that glycans were responsible for the antiviral activity of CN. Furthermore, an evanescent-field fluorescence-assisted assay showed that HRV particles directly bound to heated casein (at 95°C for 30 min) in a viral titer–dependent manner. Although the heated κ-CN retained inhibitory activity in a neutralization assay, the activity was weaker than that observed before heat treatment. Our findings indicate that the inhibitory mechanism of bovine κ-CN against HRV involves direct binding to viral particles via glycan residues. In addition, heat-labile structures in κ-CN may play an important role in maintenance of κ-CN binding to HRV.

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