Long Non-Coding RNA THRIL Promotes Influenza Virus Replication by Inhibiting the Antiviral Innate Immune Response

Long non-coding RNAs (lncRNAs) have been recognized for their crucial roles in the replication processes of various viruses. However, the specific functions and regulatory mechanisms of many lncRNAs in influenza A virus (IAV) pathogenesis remain poorly understood. In this study, we identified lncRNA THRIL and observed a significant reduction in its expression following IAV infection in A549 cells. The treatment of cells with the viral mimic poly (I:C), or with type I and type III interferons, resulted in a substantial decrease in THRIL expression. Furthermore, THRIL overexpression significantly enhanced IAV replication, while its silencing markedly reduced IAV replication. Additionally, IAV infection led to notable reductions in the expression levels of type I and type III interferons in cell lines overexpressing THRIL compared to control groups; conversely, cell lines with THRIL knockdown exhibited significantly higher interferon levels than control groups. Moreover, THRIL was found to inhibit the expression of several critical interferon-stimulated genes (ISGs), which are essential for an effective antiviral response. Notably, our findings demonstrated that THRIL impaired the activation of IRF3, a key transcription factor in the interferon signaling pathway, thereby suppressing host innate immunity. These results highlight THRIL's potential as a therapeutic target for antiviral strategies.