Inhibition of foot-and-mouth disease virus replication by small interfering RNA

Foot-and-mouth disease, caused by foot-and-mouth disease virus (FMDV), is one of the most dangerous diseases of cloven-hoofed animals and is a constant threat to the dairy and beef industries in the Middle East and other regions of the world, despite intensive vaccination programmes. In this work, the ability of specific small interfering (si)RNAs to inhibit virus replication in BHK-21 cells was examined. By using bioinformatic computer programs, all FMDV sequences in public-domain databases were analysed. The analysis revealed three regions of at least 22 bp with 100 % identity in all FMDV entries. From these sequences, three specific siRNA molecules were prepared and used to test the ability of siRNAs to inhibit virus replication. By using real-time quantitative PCR to measure the amount of viral RNA in infected cells, it was shown that virus replication was inhibited in cells that were transfected with siRNAs. When viral titres were examined, 100 % inhibition of growth could be demonstrated in cells transfected with a mixture of all three anti-FMDV siRNAs, compared with control cells transfected with anti-LacZ siRNA.