FIG. 3.

Assignment of the BSNV polyprotein processing products and of the VP4 protease active site. (A) Schematic representation of the BSNA polyprotein and the derived constructs produced by expression of plasmids. The position of the mutated VP4 catalytic residues is indicated (•). (B) (Left panel) In vitro expression of the wild type (pVP2-[X]-VP4-VP3) and of the derived constructs was carried out with a rabbit reticulocyte expression system. Expression products were analyzed by SDS-PAGE (10% polyacrylamide), and gels were processed for autoradiography. The locations of the viral polypeptides are indicated on the right. The asterisk indicates a 65-kDa band. (Right panel) Comparison including the amino sequences of VP4 of IPNV, IBDV, and DXV (shown as DrXV). The active site residues (Ser-692 and Lys-729) of the BSNV VP4 are indicated (•).