Although modulation of these 2 miRs by IFN b has never been described before, it is consistently observed in all clones suggesting that it may be part of the endogenous IFN response to HCV. The IFN pathway is a highly regulated process and sev eral controls has been evolved to activate and turn off this pathway. In this scenario, the temporal modulation of specific miRs seems to represent one of the control Inhibitors,Modulators,Libraries elements. It is important to note that this process cannot properly occur in cells sustaining HCV replica tion. In this case a chronic up or down regulation of IFN miRs, likely induced by the virus, may negatively affect the control of the pathway finally improving the efficacy of the antiviral effectors. It would be interesting to investigate whether the experimental use of miR inhi bitors or miR mimics could influence the control of the endogenous IFN system.

Among the 37 predicted target genes showing an inverse expression relationship with the 3 miRs, four genes were identified as Inhibitors,Modulators,Libraries Interferon Regulated AV-951 Genes according to the INTERFEROME database. One of these genes is a predicted target gene of miR 196a while the other three are all targeted by miR 142 3p. Importantly, in autoimmune diseases the high mobility group box 1 protein was identified as a component of immune complex containing DNA or RNA, which may act as endogenous IFN b inducer. Down regulation of HMGB1 gene in all HCV replicon clones suggests that it might contribute to impair the activation of the IFN signaling. Currently, the role of these four IRGs in the IFN response to HCV repli cation is unknown.

Thus, unraveling their contribution to the regulation of the IFN response may reveal new mechanisms of viral persistence. Gene Ontology annotations of the 37 common genes also revealed the presence of two genes, UBE2E3 and ATAD2 targets of miR 128a and miR 142 3p respectively, which are involved in the Ubiquitin proteasome pathway. Inhibitors,Modulators,Libraries The contribution of this pathway to HCV subversion of the IFN response has never been investigated. This is a quite interesting issue as several viruses use the ubiquitin proteasome system to destabilize proteins, such as IRF3 and STAT proteins, Inhibitors,Modulators,Libraries that are important for transcription of Interferon and Interferon stimulated genes.

In attempt to validate our data, we found that 4 out of 37 genes, targeted by the 3 miRs, were also modulated, in a concerted fashion, in HCV genotype 2a chimeric virus J6 JFH microarray datasets supporting the biological relevance of our results. In addition, 6 genes selected from the HCV clones microarray dataset were found to be modulated in a same way in liver biopsies of patients showing non CC IL28B polymorphism. This polymorphism is not a good predictor of response to IFN therapy and it is also associated with higher level of ISG expression in the liver and propension to chroni city.