Specific inhibition of coxsackievirus B3 translation and replication by phosphorothioate antisense...

The 5' and 3' untranslated regions (UTRs) of coxsackievirus B3 (CVB3) RNA form highly ordered secondary structures that have been confirmed to play important regulatory roles in viral cap-independent internal translation initiation and RNA replication. We previously demonstrated that deletions in different regions of the 5' UTR significantly reduced viral RNA translation and infectivity. Such observations suggested strongly that viral RNA translation and replication could be blocked if highly specific antisense oligodeoxynucleotides (AS-ODNs) were applied to target crucial sites within the 5' and 3' UTRs. In this study, seven phosphorothioate AS-ODNs were synthesized, and the antiviral activity was evaluated by Lipofectin transfection of HeLa cells with AS-ODNs followed by infection of CVB3. Analysis by Western blotting, reverse transcription-PCR, and viral plaque assay demonstrated that viral protein synthesis, genome replication, and infectivity of CVB3 were strongly inhibited by the AS-ODNs complementary to different regions of the 5' and 3' UTRs. The most effective sites are located at the proximate terminus of the 5' UTR (AS-1), the proximate terminus of the 3' UTR (AS-7), the core sequence of the internal ribosome entry site (AS-2), and the translation initiation codon region (AS-4). These AS-ODNs showed highly sequence-specific and dose-dependent inhibitory effects on both viral protein synthesis and RNA replication. It is noteworthy that the highest inhibitory activities were obtained with AS-1 and AS-7 targeting the termini of the 5' and 3' UTRs. The percent inhibition values of AS-1 and AS-7 for CVB3 protein VP1 synthesis and RNA replication were 70.6 and 79.6 for AS-1 and 73.7 and 79.7 for AS-7, respectively. These data suggest that CVB3 infectivity can be inhibited effectively by AS-ODNs.