Heterotypic inhibition of foot-and-mouth disease virus infection by combinations of RNA transcripts corresponding to the 5′ and 3′ regions

Strategies to inhibit RNA virus multiplication based on the use of interfering nucleic acids have to consider the high genetic polymorphism exhibited by this group of viruses. Here, we report high levels of heterotypic inhibition of foot-and-mouth disease virus (FMDV) infective particle formation in cotransfection experiments of susceptible cell lines with infections viral RNA and combinations of viral transcripts. The interfering molecules used include the following regions on type C FMDV RNA: (i) sequences from the 5′ region, spanning the proximal part of the internal ribosome entry site element and the two functional initiator AUGs; and (ii) the 3′ terminal region including the 3′ end of 3D gene and the complete 3′ non-coding region. Combination of 5′ antisense RNA molecules with either sense or antisense RNA molecules from the 3′ region resulted in inhibition of up to 90% of the infectivity of homologous type C FMDV RNA. The inhibition was dose-dependent and specific, as no reduction was observed in the plaque-forming units recovered from RNA of swine vesicular disease virus, a related picornavirus. Interestingly, high levels of intertypic inhibition, about 60% or higher, were observed when viral RNAs of serotypes O and A were analysed. These levels of inhibition are consistent with the levels of nucleotide homology exhibited by the viruses analysed in the target sequences. Inhibition of virus yield was also observed in FMDV-infected cells transiently expressing the interfering RNAs. Thus, transcripts of the FMDV RNA corresponding to the 5′ and 3′ regions specifically inhibit FMDV particle formation in a serotype-independent manner.