FIG. 7.

RT-PCR analysis of the r-wtFIPV, FIPVΔ7b, and FIPVΔMlu recombinants. RT-PCR was used to amplify the ORF 7b region (A and B) and the N gene region (C and D) with RNA isolated from cells infected with r-wtFIPV and FIPVΔ7b (A) and with r-wtFIPV and FIPVΔMlu (C) as a template, respectively. A physical map of the FIPV genome is shown in the middle of the figure. The locations of the primers (see Table 1 for sequences) are indicated by arrows, together with the expected sizes of the PCR products predicted for the indicated primer pairs. (B) Sequence of the ORF 7ab region with the gene 7b start codon in boldface and italics (bottom) and with the introduced mutations disrupting this codon and creating a PmlI restriction site indicated (top, underlined). (A) RT-PCR products obtained with RNA from four independent FIPVΔ7b mutant viruses with primers PR76 and PR1295. Undigested products are at the top, and products digested with PmlI are at the bottom. (D) Partial sequence of the N gene with the MluI restriction site underlined. (C) RT-PCR products obtained with RNA from four independent FIPVΔMlu mutant viruses with the primers PR1248 and PR1251. Products digested with XbaI are at the top, and products digested with XbaI and MluI are at the bottom.