Ribavirin Treatment Up-Regulates Antiviral Gene Expression via the Interferon-Stimulated Response Element in Respiratory Syncytial Virus-Infected Epithelial Cells (original) (raw)

2003, Journal of Virology

RSV replication is a potent activator of the epithelial-cell genomic response, influencing the expression of a spectrum of cellular pathways, including proinflammatory chemokines of the CC, CXC, and CX 3 C subclasses. Ribavirin (1-␤-D-ribofuranosyl-1,2,4-triazole-3-carboxamide) is a nontoxic antiviral agent currently licensed for the treatment of severe RSV lower respiratory tract infections. Because ribavirin treatment reduces the cytopathic effect in infected cells, we used high-density microarrays to investigate the hypothesis that ribavirin modifies the virus-induced epithelial genomic response to replicating virus. Ribavirin treatment administered in concentrations of 10 to 100 g/ml potently inhibited RSV transcription, thereby reducing the level of RSV N transcripts to ϳ13% of levels in nontreated cells. We observed that in both the absence and the presence of ribavirin, RSV infection induced global alterations in the host epithelial cell, affecting ϳ49% of the ϳ6,650 expressed genes detectable by the microarray. , complement products, acute-phase response factors, and the STAT and IRF transcription factors. Because IFN-␤ expression itself was reduced in the ribavirin-treated cells, we further investigated the mechanism for up-regulation of the IFN-signaling pathway. Enhanced expression of IFI 6-16, IFI 9-27, MxA/p78, STAT-1␣, STAT-1␤, IRF-7B, and TAP-1-LMP2 transcripts were independently reproduced by Northern blot analysis. Ribavirin-enhanced TAP-1-LMP2 expression was a transcriptional event where site mutations of the IFN-stimulated response element (ISRE) blocked RSV and ribavirin-inducible promoter activity. Furthermore, ribavirin up-regulated the transcriptional activity of a reporter gene selectively driven by the ISRE. In specific DNA pull-down assays, we observed that ribavirin enhanced RSV-induced STAT-1 binding to the ISRE. We conclude that ribavirin potentiates virus-induced ISRE signaling to enhance the expression of antiviral ISGs, suggesting a mechanism for the efficacy of combined treatment with ribavirin and IFN in other chronic viral diseases.