Rotavirus spike protein VP5* binds α2β1 integrin on the cell surface and competes with virus for cell binding and infectivity

Abstract

Rotaviruses recognize several cell-surface molecules, including the α2β1 integrin, and the processes of rotavirus cell attachment and entry appear to be multifactorial. The VP5* subunit of the rotavirus spike protein VP4 contains the α2β1 ligand sequence Asp–Gly–Glu at residues 308–310. Binding to α2β1 and infectivity of monkey rotavirus strain RRV and human rotavirus strain Wa, but not porcine rotavirus strain CRW-8, are inhibited by peptides containing Asp–Gly–Glu. Asp308 and Gly309 are necessary for the binding of RRV VP5* (aa 248–474) to expressed I domain of the α2 integrin subunit. Here, the ability of RRV VP5* to bind cells and affect rotavirus–integrin interactions was determined. Interestingly, VP5* bound to cells at 4 and 37 °C, both via α2β1 and independently of this integrin. Prior VP5* binding at 37 °C eliminated RRV binding to cellular α2β1 and reduced RRV and Wa infectivity in MA104 cells by 38–46 %. VP5* binding did not affect the infectivity of CRW-8. VP5* binding at 4 °C did not affect permissive-cell infection by RRV, indicating an energy requirement for VP5* competition with virus for infectivity. Mutagenesis of VP5* Asp308 and Gly309 eliminated VP5* binding to α2β1 and the VP5* inhibition of rotavirus cell binding and infection, but not α2β1-independent cell binding by VP5*. These studies show for the first time that expressed VP5* binds cell-surface α2β1 using Asp308 and Gly309 and inhibits the infection of homologous and heterologous rotaviruses that use α2β1 as a receptor.