Poliovirus 5 '-terminal cloverleaf RNA is required in cis for VPg uridylylation and the initiation of negative-strand RNA synthesis

Chimeric poliovirus RNAs, possessing the 5' nontranslated region (NTR) of h epatitis C virus in place of the 5' NTR of poliovirus, were used to examine the role of the poliovirus 5' NTR in viral replication. The chimeric viral RNAs were incubated in cell-free reaction mixtures capable of supporting t he sequential translation and replication of poliovirus RNA. Using preiniti ation RNA replication complexes formed in these reactions, we demonstrated that the 3' NTR of poliovirus RNA was insufficient, by itself, to recruit t he viral replication proteins required for negative-strand RNA synthesis. T he 5'-terminal cloverleaf of poliovirus RNA was required in cis to form fun ctional preinitiation RNA replication complexes capable of uridylylating VP g and initiating the synthesis of negative-strand RNA. These results are co nsistent with a model in which the 5'-terminal cloverleaf and 3' NTRs of po liovirus RNA interact via temporally dynamic ribonucleoprotein complexes to coordinately mediate and regulate the sequential translation and replicati on of poliovirus RNA.