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J Dairy Sci. 2014 May;97(5):2653-61. doi: 10.3168/jds.2013-7792. Epub 2014 Mar 5.

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

Author information

1
United Graduate School of Agricultural Science, Gifu University, 1-1 Yanagido, Gifu, Gifu 501-1193, Japan.
2
Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, Gifu 501-1193, Japan.
3
Faculty of Pharmaceutical Science, Kinki University, 3-4-1 Kowakae, Higashi-Osaka, Osaka 577-8502, Japan.
4
Central R&D Laboratory, Kobayashi Pharmaceutical Co. Ltd., 1-30-3 Toyokawa, Ibaraki, Osaka 567-0057, Japan.
5
United Graduate School of Agricultural Science, Gifu University, 1-1 Yanagido, Gifu, Gifu 501-1193, Japan; Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, Gifu 501-1193, Japan.
6
Department of Molecular Microbiology and Immunology, Graduate School of Biomedical Sciences and Global Center of Excellence, Nagasaki University, 1-12-4 Sakamoto, Nagasaki, Nagasaki 852-8523, Japan.
7
United Graduate School of Agricultural Science, Gifu University, 1-1 Yanagido, Gifu, Gifu 501-1193, Japan; Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, Gifu 501-1193, Japan. Electronic address: kanamaru@gifu-u.ac.jp.

Abstract

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.

KEYWORDS:

colostrum; human rotavirus; κ-casein

PMID:
24612801
DOI:
10.3168/jds.2013-7792
[Indexed for MEDLINE]
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