Nitric oxide inhibition of coxsackievirus replication in vitro

Nitric oxide is a radical molecule with antibacterial, -parasitic, and - viral properties. We investigated the mechanism of NO inhibition of Coxsackievirus B3 (CVB3) replication in vitro by determining the effect of NO upon a single replicative cycle of CVB3 grown in HeLa cells. Transfection of inducible NO synthase cDNA into HeLa cells reduces the number of viral particles produced during a single cycle of growth. Similarly, a noncytotoxic concentration of the NO donor S-nitroso-amino-penicillamine reduces the number of vital particles in a dose-dependent manner. To explore the mechanisms by which NO exerts its antiviral effect, we assayed the attachment, replication, and translation steps of the CVB₃ life cycle. NO does not affect the attachment of CVB3 to HeLa cells. However, NO inhibits CVB3 RNA synthesis, as shown by a [³H]uridine incorporation assay, reverse transcription-PCR, and Northern analysis. In addition, NO inhibits CVB3 protein synthesis, as shown by [³⁵S]methionine protein labeling and Western blot analysis of infected cells. Thus, NO inhibits CVB3 replication in part by inhibiting viral RNA synthesis by an unknown mechanism.