2′- C-Methylcytidine as a potent and selective inhibitor of the replication of foot-and-mouth disease virus

We report on the potent and selective in vitro antiviral activity of 2′- C-methylcytidine (2′- C-MetCyt) against foot-and-mouth disease virus (FMDV). FMDV belongs to the Picornaviridae and has the potential to cause devastating epidemics in livestock. The 50% and 90% effective concentrations (EC 50 and EC 90) for inhibition of the FMDV-induced cytopathic effect (CPE) formation were 6.4 ± 3.8 and 10.8 ± 5.4 μM. Comparable EC 50 values for inhibition of viral RNA synthesis were observed. Treatment of FMDV-infected BHK-21 cells with 77 μM 2′- C-MetCyt resulted in a (1.6–3.2) × 10 3-fold reduction of infectious virus yield. Time-of-drug addition experiments suggest that 2′- C-MetCyt interacts with viral replication at a time point that coincides with the onset of intracellular viral RNA synthesis. In contrast to emergency vaccination, a potent and selective antiviral agent may provide almost immediate (prophylactic/therapeutic) protection against infection and thus constitute an important alternative/supplementary option to contain outbreaks such as those caused by FMDV.