Integrin-Using Rotaviruses Bind 21 Integrin 2 I Domain via VP4 DGE Sequence and Recognize X2 and V3 by Using

Integrins 21, X2, and V3 have been implicated in rotavirus cell attachment and entry. The virus spike protein VP4 contains the 21 ligand sequence DGE at amino acid positions 308 to 310, and the outer capsid protein VP7 contains the X2 ligand sequence GPR. To determine the viral proteins and sequences involved and to define the roles of 21, X2, and V3, we analyzed the ability of rotaviruses and their reassortants to use these integrins for cell binding and infection and the effect of peptides DGEA and GPRP on these events. Many laboratory-adapted human, monkey, and bovine viruses used integrins, whereas all porcine viruses were integrin independent. The integrin-using rotavirus strains each interacted with all three integrins. Integrin usage related to VP4 serotype independently of sialic acid usage. Analysis of rotavirus reassortants and assays of virus binding and infectivity in integrin-transfected cells showed that VP4 bound 21, and VP7 interacted with X2 and V3 at a postbinding stage. DGEA inhibited rotavirus binding to 21 and infectivity, whereas GPRP binding to X2 inhibited infectivity but not binding. The truncated VP5* subunit of VP4, expressed as a glutathione S-transferase fusion protein, bound the expressed 2 I domain. Alanine mutagenesis of D308 and G309 in VP5 * eliminated VP5 * binding to the 2 I domain. In a novel process, integrin-using viruses bind the 2 I domain of 21 via DGE in VP4 and interact with X2 (vi