VP3) (Figure 5.1b) and the smallest structural protein VP4, which are arranged in the order VP2-VP4-VP1-VP3 in the polyprotein (Figure 5.1c). The structural proteins are proteolytically processed by the 3C protease domain encoded by the nonstructural block (Figure 5.1c), and precise processing sites have been experimentally determined for several iaviruses, including deformed wing virus (DWV) [3] and Lymantria dispar iflavirus 1 [4] (Figure 5.1c). The C-terminal half of the iaviral polyprotein contains domains with motifs typical for picornaviral 2C RNA helicase, a chymotrypsin-like 3C protease and 3D RNA-dependent RNA polymerase (Figure 5.1c) [5]. No experimental data are available on the procession of the nonstructural portion of iavirus polyprotein, although it is suggested that the processing of the nonstructural proteins is facilitated by the 2C protease similar to the processing of the picornavirus polyproteins.