The interferon-inducible antiviral protein Daxx is not essential for interferon-mediated protection against avian sarcoma virus

Background: The antiviral protein Daxx acts as a restriction factor of avian sarcoma virus (ASV; Retroviridae) in mammalian cells by promoting epigenetic silencing of integrated proviral DNA. Although Daxx is encoded by a type I (alpha/beta) interferon-stimulated gene, the requirement for Daxx in the interferon anti-retroviral response has not been elucidated. In this report, we describe the results of experiments designed to investigate the role of Daxx in the type I interferon-induced anti-ASV response. Findings: Using an ASV reporter system, we show that type I interferons are potent inhibitors of ASV replication. We demonstrate that, while Daxx is necessary to silence ASV gene expression in the absence of interferons, type I interferons are fully-capable of inducing an antiviral state in the absence of Daxx. Conclusions: These results provide evidence that Daxx is not essential for the anti-ASV interferon response in mammalian cells, and that interferons deploy multiple, redundant antiviral mechanisms to protect cells from ASV.