Fig. 5.

Silencing of PCBP1 and PCBP2 results in reduced PRRSV growth. (A) Reduction in PCBP1 and PCBP2 protein levels after siRNA treatment. MARC-145 cells transfected with no siRNA (No), scramble siRNA (Sc), or different concentrations (nM) of siRNAs for PCBP1 and/or PCBP2 (as shown on top of the lanes) were harvested 72 hpt. Endogenous PCBP1 and PCBP2 were detected by immunoblotting using antibodies directed against these proteins. The blots were also probed for β-actin to confirm equal protein loading. (B) MARC-145 cells were treated with scramble (Sc) or GAPDH-specific siRNAs for 72 h, and GAPDH protein was detected by immunoblotting. (C) MARC-145 cells treated for 72 h with various siRNAs were infected with FL12 virus at an MOI of 0.1. Culture supernatants were harvested at 12 h and 24 hpi, and viral titers were determined by plaque assay. Error bars represent standard error of mean from 3 different experiments. Mean titers which are significantly different are labeled with different letters on top of the bar. (D) The IFN-β mRNA and RPL32 mRNA (internal control) were measured by RT-PCR from MARC-145 cells treated with indicated siRNAs (on top) and either mock infected or infected with FL12 virus for 18 h. Sendai virus (SeV)-infected MARC-145 cells were used as a positive control for IFN induction.