Interaction of West Nile virus with α<inf>v</inf>β<inf>3</inf> integrin mediates virus entry into cells

Abstract

The functional receptor for the flavivirus West Nile (WNV) infection has been characterized in this study with a combination of biochemical and molecular approaches. A 105-kDa protease-sensitive glycoprotein that binds WNV was isolated from the plasma membrane of cells permissive to WNV infection. The protein was subjected to peptide sequencing, and this glycoprotein was identified as a member of the integrin superfamily. Infection of WNV was shown to be markedly inhibited in Vero cells pretreated with blocking antibodies against αvβ3 integrin and its subunits by receptor competition assay. It was also noted that cells pretreated with antibodies against αvβ3 integrin can effectively inhibit flavivirus Japanese encephalitis but to a lesser extent flavivirus dengue infections. West Nile virus entry is independent of divalent cations and is not highly blocked by arginine-glycine-aspartic acid (RGD) peptides, suggesting that the interaction between the virus and αvβ3 integrin is not highly dependent on the classical RGD binding motif. In addition, gene silencing of the β3 integrin subunit in cells has resulted in cells largely resistant to WNV infection. In contrast, expression of recombinant human β3 integrin substantially increased the permissiveness of CS-1 melanoma cells for WNV infection. Soluble αVβ3 integrin can also effectively block WNV infection in a dose-dependent manner. Furthermore, WNV infection also triggered the outside-in signaling pathway via the activation of integrin-associated focal adhesion kinase. The identification of αvβ3 integrin as a receptor for WNV provides insight into virus-receptor interaction, hence creating opportunities in the development of anti-viral strategies against WNV infection.