Rotaviruses are characterized by a triple-layered protein capsid composed of four major structural proteins. Viral protein (VP)2 comprises the innermost layer, in which the dsRNA genome is contained, while the middle layer consists of VP6. The outer layer of the virion is composed of the VP7 glycoprotein and proteasesensitive VP4 spikes [31] . Although both triple-and doublelayered particles (TLPs and DLPs, respectively) are generated during rotavirus replication, only TLPs are infectious, due to the requirements of VP4 and VP7 for cell binding, and trypsin cleavage of VP4 for viral entry and infectivity [32, 33, 34, 35, 36] . Formation of noninfectious empty TLPs and DLPs, which lack the viral genome, is also observed during infection. The nonstructural proteins (NSP1 through 5) are involved in viral replication, morphogenesis and assembly, but they are not expressed by nonreplicating virus and are not part of the infectious virion [31] .