Comparison of the amount of VP0 and VP2 in 155S particles produced in reactions with and without extra 3CDpro(3CproH40A). Translation RNA-replication reactions were carried out either in the absence or in the presence of extra 3CDpro(3CproH40A) or 3CDpro(3CproH40G, 3DpolR455A/R456A). The reaction products were separated on sucrose gradients, and the peak fractions were run on a SDS-polyacrylamide gel. Western blots were done with a polyclonal antibody to VP2 (Materials and Methods). The amount of VP0 and VP2 in fractions 8–10, in the 155S peak of the gradient shown on Fig. 6, was determined. (A) extra 3CDpro(3CproH40A) added; (B) no extra 3CDpro(3CproH40A) added; (C) 3CDpro(3CproH40G, 3DpolR455A/R456A) added. Lane 1: fraction 8; lane 2, fraction 9; lane 3: fraction 10 of the 155S peak shown in Fig. 6.