Fig. 1.

Multifunctionality of RNA virus capsid proteins. A generic RNA virus is used as the model. Virions consist of a host-derived lipid envelope containing virus-encoded membrane glycoproteins. The interior of the virion consists of genomic RNA bound to capsid proteins. Upon entry, deposition of nucleocapid into the cytoplasm provides the first opportunity for capsids to interact with signaling proteins. The viral genome is translated to produce structural and nonstructural proteins. The nonstructural proteins function in replication of the genome whereas the structural proteins function in assembly of new virions. Recent evidence suggests that nascent viral capsids also interface with cellular proteins to alter the host cell environment so that it is more permissive for viral replication.