Fig. 3. Analysis of virus stability for foreign gene expression.

A) Titer of rZHΔNSs-GFP and rZHΔNSs-Fluc after rescue (P0) or passaged one to four times (P1–P4) on Vero cells at a moi=0.001 and recovered at day 3. B) Luciferase activity in Vero cells infected with different passages of rZHΔNSs-FLuc at a moi=3, expressed in arbitrary units per 2.5×10⁴ cells. Mean of triplicate assays. C) Gel analysis of RT-PCR products representing the full-length S segment of rZHΔNSs-GFP and rZHΔNSs-Fluc at P0 and P4. RT-PCR was performed using total RNA extracted at 15h p.i. from Vero cells infected by these viruses or ZH548 and rZHΔNSs.