FIG. 3.

Exchanges between the 5′ termini of WT and 3′CB. (A) Sequences of altered Tr regions. Four subgenomic replicons, Tr(LeC34-46), Tr(LeC23-46), Tr(LeC9-12,34-46), and Tr(LeC19-29), that contained 5′ terminal sequences derived from both LeC and the natural Tr are shown. To illustrate the sequence differences between Tr and LeC, the 5′ termini of WT and 3′CB are shown. (B) RNA synthesis, determined by agarose-urea gel analysis of VSV-specific RNAs generated from genomic analogs with altered Tr sequences. RNAs were labeled with [³H]uridine in the presence of ActD and analyzed as described in Materials and Methods. The products of replication and transcription by the VSV polymerase are indicated by Rep and Tx, respectively. (C) Infectivity assay. Shown is agarose-urea gel analysis of VSV-specific RNAs generated by infectious particles recovered from genomic analogs containing altered Tr sequences. Supernatants were generated and tested for infectious particles by the infectivity assay described in Materials and Methods.