FIG. 2.

Construction and composition of the transcription vectors pBRDI1 and pBRDI2, the templates for the synthetic donor RNA fragments A and B, respectively. (A) Shown at the top is a schematic representation of the FIPV 79-1146 genome. The shaded bars represent the various FIPV cDNA clones used to assemble pBRDI1. For details, see Materials and Methods. Small arrows indicate the primers (see Table 1 for primer numbers, sequences, and locations) used to generate the various fragments (see Materials and Methods). The dotted bars represent sequences encoding the MHV S ectodomain (pTMFS and pTMFS1 are not drawn to scale). The broad line at the left of each vector indicates pBRXN vector sequences. T7, 5′, 3′, and A indicate the T7 RNA polymerase transcription promoter sequence, the 5′- and 3′-untranslated region sequences, and a polyadenylate segment, respectively. Restriction sites relevant to plasmid construction are shown. (B) Some sequences are specified: I, the T7 promoter sequence preceded by a XhoI restriction sequence and followed by the sequence of the 5′-terminal region; the transcriptional start is indicated by an asterisk; and II, the in-frame transition of the 5′ ORF 1a and the 3′ ORF 1b sequences. Base pairs changed to create an unique SacI restriction site are in italics and in boldface. Below the nucleotide sequence the amino acid sequence is shown, with the residues that were changed due to the introduction of the SacI site indicated in boldface.