Wnt/β-catenin signaling is an essential pathway in cell cycle control. Dysregulation of the Wnt/β-catenin signaling pathway during viral infection has been reported. In this study, we examined the effect of modulating Wnt/β-catenin signaling during influenza virus infection. The activation of the Wnt/β-catenin pathway by Wnt3a increased influenza virus mRNA and virus production in in vitro in mouse lung epithelial E10 cells and mRNA expresson of influenza virus genes in vivo in the lungs of mice infected with influenza virus A/Puerto Rico/8/34. However, the inhibition of Wnt/β-catenin signaling by iCRT14 reduced virus titer and viral gene expression in human lung epithelial A549 cells and viral replication in primary mouse alveolar epithelial cells infected with different influenza virus strains. Knockdown of β-catenin also reduced viral protein expression and virus production. iCRT14 acts at the early stage of virus replication. Treatment with iCRT14 inhibited the expression of the viral genes (vRNA, cRNA and mRNA) evaluated in this study. The intraperitoneal administration of iCRT14 reduced viral load, improved clinical signs, and partially protected mice from influenza virus infection.

Due to the frequent mutations, influenza A virus (IAV) becomes resistant to anti‐viral drugs targeting influenza viral proteins. There are increasing interests in anti‐viral agents that target host cellular proteins required for virus replication. Tankyrase (TNKS) has poly (ADP‐ribose) polymerase activity and is a negative regulator of many host proteins. The objectives of this study are to study the role of TNKS2 in IAV infection, identify the microRNAs targeting TNKS2, and to understand the mechanisms involved. We found that TNKS2 expression was elevated in human lung epithelial cells and mouse lungs during IAV infection. Knock‐down of TNKS2 by RNA interference reduced viral replication. Using a computation approach and 3′‐untranslation regions (3′‐UTR) reporter assay, we identified miR‐206 as the microRNA that targeted TNKS2. Overexpression of miR‐206 reduced viral protein levels and virus production in cell culture. The effect of miR‐206 on IAV replication was strain‐independent. miR‐206 activated JNK/c‐Jun signalling, induced type I interferon expression and enhanced Stat signalling. Finally, the delivery of an adenovirus expressing miR‐206 into the lung of mice challenged with IAV increased type I interferon response, suppressed viral load in the lungs and increased survival. Our results indicate that miR‐206 has anti‐influenza activity by targeting TNKS2 and subsequently activating the anti‐viral state.

Due to an increasing emergence of new and drug-resistant strains of the influenza A virus (IAV), developing novel measures to combat influenza is necessary. We have previously shown that inhibiting Wnt/β-catenin pathway reduces IAV infection. In this study, we aimed to identify antiviral human microRNAs (miRNAs) that target the Wnt/β-catenin signalling pathway. Using a miRNA expression library, we identified 85 miRNAs that up-regulated and 20 miRNAs that down-regulated the Wnt/β-catenin signalling pathway. Fifteen miRNAs were validated to up-regulate and five miRNAs to down-regulate the pathway. Overexpression of four selected miRNAs (miR-193b, miR-548f-1, miR-1-1, and miR-509-1) that down-regulated the Wnt/βcatenin signalling pathway reduced viral mRNA, protein levels in A/PR/8/34-infected HEK293 cells, and progeny virus production. Overexpression of miR-193b in lung epithelial A549 cells also resulted in decreases of A/PR/8/34 infection. Furthermore, miR-193b inhibited the replication of various strains, including H1N1 (A/PR/8/34, A/WSN/ 33, A/Oklahoma/3052/09) and H3N2 (A/Oklahoma/309/2006), as determined by a viral reporter luciferase assay. Further studies revealed that β-catenin was a target of miR-193b, and β-catenin rescued miR-193b-mediated suppression of IAV infection. miR-193b induced G0/G1 cell cycle arrest and delayed vRNP nuclear import. Finally, adenovirus-mediated gene transfer of miR-193b to the lung reduced viral load in mice challenged by a sublethal dose of A/PR/8/34. Collectively, our findings suggest that miR-193b represses IAV infection by inhibiting Wnt/β-catenin signalling. KEYWORDS cell cycle arrest, influenza A virus, microRNA, miR-193b, vRNP nuclear import, Wnt/β-catenin signaling

Since the discovery of the Bourbon virus (BRBV) in 2014, a total of five human cases have been identified, including two fatal cases. BRBV is thought to be transmitted by the lone star tick, which is prevalent in the eastern, southeastern, and midwestern United States.