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.