Expression in E. coli and purification of the active autoprotease P20 of classical swine fever virus.

The genes for Flaviviridae structural proteins are located at the 5' terminus of the genome, while the 3' terminus contains the genes for the non-structural proteins. The first protein product of the large ORF of pestiviruses, the p20 protein, is however a non-structural protein which possess an autoproteolytic activity. Here we report the cloning of the p20/p14 genes behind the strong Trc promotor and expression of the p20 at high levels in E. coli. The autoprotease p20 was responsible for its own release from the nascent polyprotein in E. coli and was further purified by chromatography techniques.