Table_12_miR-615 facilitates porcine epidemic diarrhea virus replication by targeting IRAK1 to inhibit type III interferon expression.DOCX

Porcine epidemic diarrhea virus (PEDV) in the Coronavirus family is a highly contagious enteric pathogen in the swine industry, which has evolved mechanisms to evade host innate immune responses. The PEDV-mediated inhibition of interferons (IFNs) has been linked to the nuclear factor-kappa B (NF-κB) pathway. MicroRNAs (miRNAs) are involved in virus–host interactions and IFN-I regulation. However, the mechanism by which the PEDV regulates IFN during PEDV infection has not yet been investigated in its natural target cells. We here report a novel mechanism of viral immune escape involving miR-615, which was screened from a high-throughput sequencing library of porcine intestinal epithelial cells (IECs) infected with PEDV. PEDV infection altered the profiles of miRNAs and the activities of several pathways involved in innate immunity. Overexpression of miR-615 increased PEDV replication, inhibited IFN expression, downregulated the NF-κB pathway, and blocked p65 nuclear translocation. In contrast, knockdown of miR-615 enhanced IFN expression, suppressed PEDV replication, and activated the NF-κB pathway. We further determined that IRAK1 is the target gene of miR-615 in IECs. Our findings show that miR-615 suppresses activation of the NF-κB pathway by suppressing the IRAK1 protein and reducing the generation of IFN-IIIs, which in turn facilitates PEDV infection in IECs. Moreover, miR-615 inhibited PEDV replication and NF-κB pathway activation in both IECs and MARC-145 cells. These findings support an important role for miR-615 in the innate immune regulation of PEDV infections and provide a novel perspective for developing new treatments.

猪流行性腹泻病毒（PEDV），隶属于冠状病毒家族，是养猪业中一种高度传染性的肠道病原体，其已进化出逃避宿主先天免疫反应的机制。PEDV介导的干扰素（IFN）抑制与核因子κB（NF-κB）途径相关联。微小RNA（miRNA）参与病毒-宿主相互作用及IFN-I的调控。然而，PEDV在感染其天然靶细胞过程中调控IFN的机制尚未得到深入研究。本研究报道了一种涉及miR-615的新型病毒免疫逃逸机制，该miR-615是从感染PEDV的猪肠道上皮细胞（IECs）的高通量测序文库中筛选出来的。PEDV感染改变了miRNA的表达谱和参与先天免疫的多条途径的活性。miR-615的过表达增加了PEDV的复制，抑制了IFN的表达，下调了NF-κB途径，并阻断了p65的核转位。相反，miR-615的敲低增强了IFN的表达，抑制了PEDV的复制，并激活了NF-κB途径。我们进一步确定IRAK1是IECs中miR-615的目标基因。我们的研究结果表明，miR-615通过抑制IRAK1蛋白的表达并减少IFN-IIIs的生成，从而抑制了NF-κB途径的激活，进而促进了PEDV在IECs中的感染。此外，miR-615在IECs和MARC-145细胞中均抑制了PEDV的复制和NF-κB途径的激活。这些发现支持了miR-615在PEDV感染先天免疫调节中的重要作用，并为开发新型治疗方案提供了新的视角。