Figure 1. Kinetics of gfp-expression after infection of NIH3T3 cells with parental virus, the deletion mutant ORF4⁻Tet⁺ or the ORF4 revertant.

Cells were infected at a multiplicity of infection of 10 for 1h at 37°C. Then, the inoculum was removed and fresh medium, without (panel A) or with (panel B) phosphonoacetic acid (PAA), was added. Cells were harvested immediately thereafter and after 6, 18 and 48 hours, respectively, and analyzed for gfp expression by FACS analysis. Data shown are means ± SD of three independent experiments. The asterisks indicate that the expression of gfp is significantly delayed after infection with the ORF4⁻Tet⁺ mutant, when compared to parental or revertant virus (p<0,02; Two-way ANOVA).