FIG. 1.

Expression of VP3 deletion mutant polypeptides reduces IBDV replication. (A) The diagram depicts the VP3 deletion mutant polypeptides M1, M2, and M3, expressed by different rBVs used in our analyses. Gray rectangles indicate the presence of six-histidine tags fused to the N termini of the different VP3-derived constructs. The upper part of the diagram represents the wild-type VP3 polypeptide (257 residues), indicating the positions of the RNA-binding (RNA-BD), oligomerization (OlD), and VP1-binding (VP1-BD) domains. (B) BSC1 cultures were transduced with recombinant baculoviruses expressing M1, M2, and M3. At 48 h posttransduction, cells were harvested and the corresponding extracts were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting using an anti-histidine tag monoclonal antibody. The positions of molecular mass markers are shown in kilodaltons (lane MW). (C) Monolayers of BSC1 cells were transduced with recombinant baculoviruses expressing EFGP (•), M1 (▪), M2 (□), and M3 (▴). Mock-transduced monolayers (○) were used as controls for this experiment. Cells were infected at 12 h after transduction with IBDV at a multiplicity of infection of 0.1 PFU/cell. At the indicated times p.i., cultures were harvested and total virus titers were determined by plaque assay on BSC1 cells.