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

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 t...

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Bibliographic Details
Published in:Journal of dairy science 2014-05, Vol.97 (5), p.2653-2661
Main Authors: Inagaki, M., Muranishi, H., Yamada, K., Kakehi, K., Uchida, K., Suzuki, T., Yabe, T., Nakagomi, T., Nakagomi, O., Kanamaru, Y.
Format: Article
Language:English
Subjects:
Animals
Caseins - chemistry
Caseins - metabolism
Caseins - pharmacology
Cattle
colostrum
Colostrum - chemistry
Female
Gastroenteritis - virology
Hot Temperature
human rotavirus
Humans
Milk - chemistry
Polysaccharides - analysis
Polysaccharides - chemistry
Polysaccharides - metabolism
Pregnancy
Rotavirus - drug effects
Rotavirus - metabolism
Rotavirus Infections - prevention & control
κ-casein
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Summary: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 30min) 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.
ISSN:0022-0302
1525-3198
DOI:10.3168/jds.2013-7792