Comparison of recombinant viruses rSCV and r7bΔTMD. (A) RT-PCRs on supernatants of Vero cells spanning the region of the ORF 7b deletion (RT-PCR 1) or targeting the sequence deleted in ORF7bΔTMD (RT-PCR 2). rSCV is the full-length ORF 7b virus; r7bΔTMD is the virus with the Frankfurt-1-specific deletion in ORF 7b as shown in Figure 1. (B) Plaque assay using crystal violet stain and immunofocus assay using a polyclonal protein patient serum reacting predominantly against the N protein (anti-N). (C) Relative Log RNA concentration (copies per mL) in viral supernatants after growth in cell lines as indicated. The zero value on the y-axis represents the starting RNA concentrations after virus absorption (1 h) and change of medium in each culture. Other data for each culture were normalized by subtraction of the logarithmic starting concentration. Each datum point shows the mean value of three independent experiments.