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Abstract Background shRNA targeting the integrin αv subunit, which is the foot-and-mouth disease virus (FMDV) receptor, plays a key role in virus attachment to susceptible cells. We constructed a RNAi lentiviral vector, iαv pLenti6/BLOCK -iT™, which expressed siRNA targeting the FMDV receptor, the porcine integrin αv subunit, on PK-15 cells. We also produced a lentiviral stock, established an iαv-PK-15 cell line, evaluated the gene silencing efficiency of mRNA using real-time qRT-PCR, integrand αv expression by indirect immunofluorescence assay (IIF) and cell enzyme linked immunosorbent assays (cell ELISA), and investigated the in vivo inhibitory effect of shRNA on FMDV replication in PK-15 cells. Results Our results indicated successful establishment of the iαv U6 RNAi entry vector and the iαv pLenti6/BLOCK -iT expression vector. The functional titer of obtained virus was 1.0 × 106 TU/mL. To compare with the control and mock group, the iαv-PK-15 group αv mRNA expression rate in group was reduced by 89.5%, whilst IIF and cell ELISA clearly indicated suppression in the experimental group. Thus, iαv-PK-15 cells could reduce virus growth by more than three-fold and there was a > 99% reduction in virus titer when cells were challenged with 102 TCID50 of FMDV. Conclusions Iαv-PK-15 cells were demonstrated as a cell model for anti-FMDV potency testing, and this study suggests that shRNA could be a viable therapeutic approach for controlling the severity of FMD infection and spread.

Abstract Background Foot-and-mouth disease virus (FMDV) causes an economically important and highly contagious disease of cloven-hoofed animals. RNAi triggered by small RNA molecules, including siRNAs and miRNAs, offers a new approach for controlling viral infections. There is no report available for FMDV inhibition by vector-delivered miRNA, although miRNA is believed to have more potential than siRNA. In this study, the inhibitory effects of vector-delivered miRNAs targeting the 3D gene on FMDV replication were examined. Results Four pairs of oligonucleotides encoding 3D-specific miRNA of FMDV were designed and selected for construction of miRNA expression plasmids. In the reporter assays, two of four miRNA expression plasmids were able to significantly silence the expression of 3D-GFP fusion proteins from the reporter plasmid, p3D-GFP, which was cotransfected with each miRNA expression plasmid. After detecting the silencing effects of the reporter genes, the inhibitory effects of FMDV replication were determined in the miRNA expression plasmid-transfected and FMDV-infected cells. Virus titration and real-time RT-PCR assays showed that the p3D715-miR and p3D983-miR plasmids were able to potently inhibit the replication of FMDV when BHK-21 cells were infected with FMDV. Conclusion Our results indicated that vector-delivered miRNAs targeting the 3D gene efficiently inhibits FMDV replication in vitro. This finding provides evidence that miRNAs could be used as a potential tool against FMDV infection.