Non-template functions of viral RNA in picornavirus replication

The genomic RNA of poliovirus and closely related picornaviruses perform template and non-template functions during viral RNA replication. The non-template functions are mediated by cis-active RNA sequences that bind viral and cellular proteins to form RNP complexes. The RNP complexes mediate temporally dynamic, long-range interactions in the viral genome and ensure the specificity of replication. The 5′ cloverleaf (5′ CL)-RNP complex serves as a key cis-active element in all of the non-template functions of viral RNA. The 5′CL-RNP complex is proposed to interact with the cre-RNP complex during VPgpUpU synthesis, the 3′NTR-poly(A) RNP complex during negative-strand initiation and the 3′ end negative-strand-RNP complex during positive-strand initiation. Co-ordinating these long-range interactions is important in regulating each step in the replication cycle.

► Cis-active elements form RNP complexes that regulate viral RNA replication.
► RNP complexes mediate long-range interactions in viral RNA.
► 5′CL-RNP complex is required in trans for VPgpUpU-primed (+) strand initiation.
► 5′–3′ circular RNP complex regulates initiation of (−) strand synthesis.
► 5′CL-RNP and cre-RNP interaction is required for VPgpUpU synthesis.