Synergistic effect of ribavirin and vaccine for protection of early infection stage of foot-and-mouth disease.

Foot-and-mouth disease (FMD) is a highly contagious viral vesicular disease of cloven hoofed animals caused by the foot-and-mouth disease virus (FMDV), which is one of the highly variable RNA viruses. In many countries, vaccines are used for the prevention of FMD. However, because there is no protection against FMD immediately after vaccination, research and development on antiviral agents is being conducted to induce protection until immunological competence is produced. Until now, no cases of the use of an instantly effective antiviral agent in the field for treatment or prevention have been reported. This study tested whether well-known chemicals used as RNA virus treatment agents had inhibitory effects on FMD viruses (FMDVs) and demonstrated that ribavirin showed antiviral effects against FMDV in vitro/in vivo . In addition, it was found that combining the administration of the antiviral agents orally and complementary therapy with vaccines synergistically enhanced antiviral activity and preserved the survival rate and body weight in the experimental animals. Antiviral agents mixed with an adjuvant were inoculated intramuscularly along with the vaccines, thereby inhibiting virus replication after injection and verifying that it was possible to induce early protection against viral infection prior to immunity achieved through the vaccine. Finally, the pigs treated with antiviral agents and vaccines showed no clinical signs and had low virus excretion. Based on these results, it is expected that this approach could be a therapeutic and preventive treatment for early protection against FMD.