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

Rotaviruses recognize several cell-surface molecules, including the alpha 2 beta 1 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 alpha 2 beta 1 ligand sequence Asp-Gly-Glu at residues 308-310. Binding to alpha 2 beta 1 and infectivity of monkey rotavirus strain RRV and human rotavirus strain Wa(1) 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 alpha 2 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 degrees C, both via alpha 2 beta 1 and independently of this integrin. Prior VP5* binding at 37 degrees C eliminated RRV binding to cellular alpha 2 beta 1 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 degrees 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 alpha 2 beta 1 and the VP5* inhibition of rotavirus cell binding and infection, but not a2 beta 1-independent cell binding by VP5*. These studies show for the first time that expressed VP5* binds cell-surface alpha 2 beta 1 using Asp308 and Gly309 and inhibits the infection of homologous and heterologous; rotaviruses that use alpha 2 beta 1 as a receptor.