Fig. 4.

Proteasome inhibition decreases viral RNA transcription and protein translation in IBDV-infected DF-1 cells. (A) The effects of proteasome inhibitor on IBDV RNA level. Total RNAs isolated from IBDV-infected cells 18 h after treatment with MG132 were subject to a real-time RT-PCR analysis of VP2 RNA. The data were normalized to the amount of β-actin mRNA and are expressed as percentages of the normalized value for IBDV-infected cells in mock-infected cells (control); they are means ± SD of values from at least three independent experiments. (B) Representative IFA staining of IBDV-infected cells used to detect VP2 protein expression. Infected DF-1 cells 18 h after treatment with various concentrations of MG132 were fixed and analyzed by immunofluorescence staining with guinea pig anti-VP2 serum. Bars, 10 μm. (C) Whole-cell extracts prepared from infected cells 18 h after treatment with the indicated proteasome inhibitors were assayed by Western blotting for the presence of VP2 expression in IBDV-infected cells