FIG. 2.
Schematic of poliovirus RNAs utilized in this study. (A) Diagram of the nonreplicating helper RNA, PV1ΔGUA3, which encodes all of the viral proteins. (B) Diagram of F3 template RNA. F3 RNA contains a frameshift mutation, as indicated in the diagram, and does not encode any viral proteins. This RNA contains two 5′-terminal nonviral G nucleotides and was used in assays for negative-strand RNA synthesis. (C) Diagram of Rz-F3 template RNA. This RNA contains a self-cleaving 5′-terminal hammerhead ribozyme that results in the formation of viral transcripts with an authentic 5′ end. Rz-F3 RNA supports the synthesis of both negative- and positive-strand product RNAs.