To further test the stimulatory effect of eEF1Bc, we also tested the RdRp activity in the presence of eEF1Bc using a mutated (+)RNA template. The mutation [SL3-2-1m(+)] opens up the closed structure in the promoter region that leads to increased template activity [39] . The mutated template showed only ,2-fold increased RNA products in the RdRp assay with eEF1Bc ( Figure 2C , lanes 3-4 versus 1-2). In contrast, eEF1Bc did not stimulate RNA products when the negative-stranded RI-III(-) RNA was used as a template in the TCV RdRp assay ( Figure 2C , lanes 9-10 versus 7-8). Thus, these data support the model that eEF1Bc can mainly stimulate (-)-strand synthesis by the RdRp on the wt 39 TBSV sequence, while it is not effective on the (-)RNA template.