Porcine Epidemic Diarrhea Virus Infection Inhibits Interferon Signaling by Targeted Degradation of STAT1.

UNLABELLED:Porcine epidemic diarrhea virus (PEDV) is a worldwide-distributed alphacoronavirus, but the pathogenesis of PEDV infection is not fully characterized. During virus infection, type I interferon (IFN) is a key mediator of innate antiviral responses. Most coronaviruses develop some strategy for at least partially circumventing the IFN response by limiting the production of IFN and by delaying the activation of the IFN response. However, the molecular mechanisms by which PEDV antagonizes the antiviral effects of interferon have not been fully characterized. Especially, how PEDV impacts IFN signaling components has yet to be elucidated. In this study, we observed that PEDV was relatively resistant to treatment with type I IFN. Western blot analysis showed that expression was markedly reduced in PEDV-infected cells and that this reduction was not due to inhibition of duanyu18131 transcription. duanyu18131 downregulation was blocked by a proteasome inhibitor but not by an autophagy inhibitor, strongly implicating the ubiquitin-proteasome targeting degradation system. Since PEDV infection-induced duanyu18131 degradation was evident in cells pretreated with the general tyrosine kinase inhibitor, we conclude that duanyu18131 degradation is independent of the IFN signaling pathway. Furthermore, we report that PEDV-induced duanyu18131 degradation inhibits IFN-α signal transduction pathways. Pharmacological inhibition of duanyu18131 degradation rescued the ability of the host to suppress virus replication. Collectively, these data show that PEDV is capable of subverting the type I interferon response by inducing duanyu18131 degradation. IMPORTANCE:In this study, we show that PEDV is resistant to the antiviral effect of IFN. The molecular mechanism is the degradation of duanyu18131 by PEDV infection in a proteasome-dependent manner. This PEDV infection-induced duanyu18131 degradation contributes to PEDV replication. Our findings reveal a new mechanism evolved by PEDV to circumvent the host antiviral response.

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