A single-plasmid reverse genetics system for the rescue of non-segmented negative-strand RNA viruses from cloned full-length cDNA.

Reverse genetics systems for non-segmented negative-strand RNA viruses rely on co-transfection of a plasmid containing the full-length viral cDNA and helper plasmids encoding essential viral replication proteins. Here, a system is presented in which virus can be rescued from a single plasmid without the need for helper plasmids in cells infected with a host-restricted recombinant poxvirus that expresses T7 RNA polymerase. This approach relies on the insertion of T7 promoter sequences in the viral cDNA at positions that allow transcription of sub-genomic RNAs encoding essential viral replication proteins.