Influenza a virus regulates interferon signaling and its associated genes; MxA and STAT3 by cellular miR-141 to ensure viral replication.

The antiviral response against influenza A virus (IAV) infection includes the induction of the interferon (IFN) signaling pathway, including activation of the STATs protein family. Subsequently, antiviral myxovirus resistance (MxA) protein and other interferon-stimulated genes control virus replication; however, the molecular interaction of viral-mediated IFN signaling needs more investigation. Host microRNAs (miRNAs) are small non-coding molecules that posttranscriptionally regulate gene expression. Here, we sought to investigate the possible involvement of miR-141 in IAV-mediated IFN signaling. Accordingly, the microarray analysis of A549 cells transfected with precursor miR-141 (pre-miR-141) was used to capture the potentially regulated genes in response to miR-141 overexpression independent of IAV infection. The downregulation of targeted genes by miR-141, in addition to viral gene expression, was investigated by quantitative real-time PCR, western blot analysis, and flow cytometric assay. Our findings showed a significant upregulation of miR-141 in infected A549 cells with different strains of IAV. Notably, IAV replication was firmly interrupted in cells transfected with the miR-141 inhibitor. While its replication significantly increased in cells transfected with pre-miR-141 confirming the crucial role of miRNA-141 in supporting virus replication. Interestingly, the microarray data of miR-141 transduced A549 cells showed many downregulated genes, including MxA, STAT3, IFI27, and LAMP3. The expression profile of MxA and STAT3 was significantly depleted in infected cells transfected with the pre-miR-141, while their expression was restored in infected cells transfected with the miR-141 inhibitor. Unlike interleukin 6 (IL-6), the production of IFN-ß markedly decreased in infected cells that transfected with pre-miR-141, while it significantly elevated in infected cells transfected with miR-141 inhibitor. These data provide evidence for the crucial role of miR-141 in regulating the antiviral gene expression induced by IFN and IL-6 signaling during IAV infection to ensure virus replication.

Assessment of the Relation Between SNP in MxA Gene and the Responsiveness of Egyptian HCV Genotype 4 Patients to Pegylated Interferon and Ribavirin Treatment.

BACKGROUND: Pegylated interferon (PegIFN) is used in the treatment of chronic hepatitis C virus (HCV) patients especially in resource limited countries. Treatment with PegIFN stimulates the expression of a number of host genes encoding enzymes with antiviral activities, including myxovirus resistance gene-A (MxA gene). MxA gene was found to have a single nucleotide polymorphism (SNP) at position -88 in the promoter region that affects the expression of MxA gene protein and was suggested to affect the treatment outcome. The aim of the work was to assess the relation between the SNP in the MxA gene and its impact on treatment of chronic HCV patients with PegIFN and ribavirin. METHODS: We therefore genotyped the biallelic G/T SNP in the promoter region of MxA gene at position -88 from the transcription start site by restriction fragment length polymorphism (RFLP) in 70 chronic HCV genotype 4 interferon naive Egyptians and 40 healthy controls. RESULTS: G allele was the prevalent one in both HCV patients group (105, 74.5%) and control group (66, 82.5%), while T allele was less expressed in patients group (36, 25.5%) and control group (14, 17.5%). There is no correlation between genotypes and response to IFN-alpha therapy: GG (OR: 0.958, 95% CI: 0.541 - 1.698, P = 0.884), GT (OR: 0.667, 95% CI: 0.188 - 2.362, P = 0.530), and TT (OR: 0.300, 95% CI: 0.083 - 1.090, P = 0.067). CONCLUSION: MxA nt-88 SNP did not affect the sustained virological response (SVR) rates after PegIFN and ribavirin combined treatment and did not act as a biological marker to potentially identify responders and non-responders to treatment. Our results call for additional large studies and/or meta-analysis of all currently available data to examine the role of MxA nt-88 SNP in predicting response to PegIFN and ribavirin in patients with IFN-alpha naive HCV genotype 4.