Lysates of cells transfected with wild type JV and JV/V5 RNA were subjected to western blot using the anti-V5 antibody ( Figure 7) . No product was present for cells transfected with wild type JV RNA, but a protein of approximately 42 kDa in size was visible in cells that had been transfected with JV/V5 RNA, confirming N-term expression and size as seen in the in vitro system. In addition, this important observation also confirms for the first time that the JV 3C protease was active in cells transfected with capped RNA as the size of the V5/N-term indicated successful cleavage of the protein from the ORF1 polyprotein.