FIGURE 1.

Structure of influenza B segment 7 and p2luc-BM2wt mRNAs. (A) Schematic of the segment 7 mRNA showing the encoded ORFs M1 and BM2 and, below, the mRNA and amino acid sequence of the overlap region. The stop codon of M1 is highlighted in bold and the start codon of BM2 is underlined. (B) Schematic of the p2luc-BM2 reporter construct. The termination–reinitiation cassette (250 nt upstream of and 20 nt downstream from the UAA UG motif) was cloned into the SalI and BamHI sites of the p2luc reporter plasmid. HpaI run-off transcripts for in vitro translation were generated using T7 RNA polymerase. The position of the T3 promoter present in the structure mapping construct p2luc-BM2-T3 is indicated.