Fig. 4.

Structure of icSARS-CoV recombinant virus ORF3a transcripts. Cultures of cells were infected with recombinant viruses. The leader-containing amplicons were purified by gel electrophoresis, subcloned, and then sequenced. (A) Organization of icSARS-CoV PRG ORF3a leader-containing transcripts. (B) ORF3a transcripts expressed in cultures transfected with chimeric recombinant genome no. 2. Cross-over sites are shown in gray boxes, and arrows represent the direction of template switching based on the transcription attenuation model for CoV RNA synthesis. Underlined ATG represents the start codon.