Figure 2.

Overview of the reverse genetics systems for the generation of infectious bunyaviruses. (a) Schematic representation of the RNA polymerase (Pol) I/II-driven reverse genetics system. Plasmids, encoding the viral RNA segments under the control of cellular RNA pol I promoter, are transfected along with RNA pol II-driven supporter plasmids expressing the nucleocapsid protein, N, and viral RNA polymerase, L, into permissive mammalian cells. The viral RNA segments, which are synthesized from the RNA pol I-driven plasmids in the nucleus, undergo replication and transcription, mediated by the expressed N and L proteins, resulting in the amplification of viral RNA genome and production of viral proteins required for the successful recovery of infectious viruses. The right panel indicates the infectious bunyaviruses rescued using the RNA Pol I/II system along with the corresponding references (Refs). (b) Schematic representation of the T7 pol-driven reverse genetics system. Plasmids, encoding the viral RNA segments under the control of T7 pol-driven promoter, are co-transfected with supporter plasmids expressing N and L proteins into suitable cells transiently or stably expressing T7 RNA polymerase. The expressed N and L proteins drive the replication and transcription of viral RNA segments, which are produced from the T7 pol-driven plasmids in the cytoplasm, resulting in the accumulation of viral RNA genome and viral proteins necessary for the recovery of infectious viruses. The panel on the right displays the infectious bunyaviruses rescued using the T7 Pol system along with the corresponding references.