Genetic diversity of a Korean echovirus 5 isolate and response of the strain to five antiviral drugs

An outbreak of echovirus 5 (ECV 5) occurred in Korea in 2006, marking the first time this virus had been identified in the country since enterovirus surveillance began in 1993. Using a sample isolated from a young male patient with aseptic meningitis, we performed sequencing of the Korean ECV 5 strain and compared it with a prototype strain (Noyce). At the nucleotide level, the P1 region (85.3%) had the highest identity value; at the amino acid level, the P3 region (98.0%) had the highest identity value. The two strains shared all cleavage sites, with the exception of the VP1/2A site, which was TY/GA in the Noyce strain but TR/GA in the Korean ECV 5 isolate. In Vero cells infected with the Korean ECV 5 isolate, no cytotoxicity was observed in the presence of azidothymidine, acyclovir, amantadine, lamivudine, or ribavirin, when the drugs were administered at a CC₅₀ value >100 μg/mL. Of the five drugs, only amantadine (IC₅₀: 1 ± 0.42 μg/mL, TI: 100) and ribavirin (IC₅₀: 22 ± 1.36 μg/mL, TI: 4.55) had any antiviral activity against the Korean ECV 5 isolate.