Abstract: A system for the generation of live Birnavirus such as infectious bursal disease virus (IBDV), a segmented double-stranded (ds)RNA virus of the Birnavirdae family, using synthetic transcripts derived from cloned DNA has been developed. Independent full-length cDNA clones were constructed which contained the entire coding and non-coding regions of RNA segments A and B of IBDV, respectively. Synthetic RNAs of both segments were produced by in vitro transcription of linearized plasmids with T7 RNA polymerase. Transfection of Vero cells with combined plus-sense transcripts of both segments generated infectious virus as early as 36 hours post-transfection. The development of a reverse genetics system for dsRNA viruses will greatly facilitate studies of the regulation of viral gene expression pathogenesis, and design of a new generation of live and inactivated vaccines.