Role of sialylated glycans on bovine lactoferrin against influenza virus

Influenza is a worldwide plague caused by the influenza virus (IAV) infection, which is initiated by specific recognition with sialic acids on host cell surface. Bovine lactoferrin (bLf) is a sialoglycoprotein belonging to the transferrin family, and it plays an important role in immune regulation. It also shows toxicity against cancer cells and pathogenic microorganisms including bacteria, fungi, and virus. The purpose of this study is to assess the roles of the sialylated glycans on bLf against IAV. To this end, bLf were first treated with sodium periodate to destroy its sialylated glycans. Then, the binding activity of native or desialylated bLf with various IAV was assessed by blotting assay. Finally, their ability to inhibit IAV attachment to host cells was analyzed in vitro. Our result showed that the sialylated glycans on bLf were almost completely destroyed by sodium periodate treatment. Furthermore, the binding activity of desialylated bLf to IAV and the ability to inhibit IAV mimics binding to MDCK cells were significantly reduced compared to that of native bLf. These results demonstrated that the sialylated glycans on bLf could serve as competitive substrates to block IAV attachment to host cells during the early stages of viral infection. Our findings make an important contribute for the fully understanding of the mechanism of bLf in the prevention of IAV infections and their possible applications in antiviral infection.