Fig. 3.

Production of RRPs by the three-plasmid system. (A) BHK cells were infected with FP-T7 and subsequently remained untreated (mock) or were transfected with plasmid pUC57-S-eGFP (S-eGFP) only, in combination with plasmid pUC57-L encoding the RVFV L genome segment (S-eGFP/L), or with the aforementioned plasmids and pCAGGS-M (GP), encoding the structural glycoproteins (S-eGFP/L/GP). The percentage of eGFP-positive cells was determined by flow cytometry (values are means and standard deviations for three replicates). (B) Schematic representation of the three-plasmid system. BHK cells were first infected with FP-T7 (step 1) and subsequently transfected with transcription plasmids pUC57-L (L) and pUC57-S-eGFP (S) and expression plasmid pCAGGS-M (step 2). After 24 h, the culture medium containing the RRPs was collected (step 3). Transcription from the expression plasmid is controlled by a CAG promoter (CAGp), and transcription from the transcription plasmids is controlled by a T7 promoter (T7p). Untranslated regions are depicted as black boxes.