Quantitative analysis of the silencing effects of vector-delivered miRNAs on FMDV replication. BHK-21 cells were transfected first with each miRNA expression plasmid and then infected with FMDV O/CHA/99. Total RNAs were extracted at 24 h and 48 h after infection for real-time quantitative RT-PCR analysis of viral gene expression using 3D-specific primers. Hamster GAPDH gene served as the internal reference. The data shown represent the mean value for three separate experiments; standard deviations indicated by error bars.