FIG. 4.

Genetic organization of the picornavirus genome. The viral RNA contains a small basic protein, VPg, at the 5′ end and a polyadenylic acid [A(n)] sequence at the 3′ end. The viral RNA is divided into three coding regions, designated P1, P2, and P3. Translation of viral RNA yields a large polyprotein, which is subsequently cleaved by 2A protease to release P1. With the exception of the autocatalytic cleavage of VP0 and the 2A-mediated alternative cleavages of 3C′ and 3D′, all the cleavages are mediated by 3C protease. 3C cleavage sites are denoted by arrows.