Spike-forming protein that mediates virion attachment to the host epithelial cell receptors and plays a major role in cell penetration, determination of host range restriction and virulence. Rotavirus entry into the host cell probably involves multiple sequential contacts between the outer capsid proteins VP4 and VP7, and the cell receptors. According to the considered strain, VP4 ses to essentially target sialic acid and/or the integrin heterodimer ITGA2/ITGB1 .Outer capsid protein VP5*: forms the spike "foot" and "body". Acts as a mbrane permeabilization protein that mediates release of viral particles from endosomal compartments into the cytoplasm. In integrin-dependent strains, VP5* targets the integrin heterodimer ITGA2/ITGB1 for cell attachment .VP8* forms the head of the spikes. It is the viral hagglutinin and an important target of neutralizing antibodies. In sialic acid-dependent strains, VP8* binds to host cell sialic acid, most probably a ganglioside, providing the initial contact .