The IBDV VP3 polypeptide counteracts VP2-induced cell responses when expressed from an eukaryotic plasmid expression vector. A. Induction of apoptosis.

Cell monolayers were mock-transfected, transfected with pcDNA3, pcDNA-VP2, pcDNA-VP3, or cotransfected with pcDNA-VP2 and pcDNA-VP3. Apoptosis was measured using the Caspase-Glo 3/7 assay kit at 48 h. post-transfection. Each determination was carried in triplicate. Presented data correspond to the mean ± the standard deviation of three independent experiments. B. PKR phosphorylation. Total extracts from cells mock-transfected, transfected with pcDNA3, pcDNA-VP2, pcDNA-VP3, or cotransfected with pcDNA-VP2 and pcDNA-VP3 were harvested at 48 h. post-transfection. Extracts were subjected to SDS-PAGE, transferred to nitrocellulose, and immunoblotted with serum anti-VP2, -VP3, -PKR, or -pT451 PKR. The WB corresponding to PKR was used as protein loading control.