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目的:探索猪流性腹泻病毒(PEDV)核衣壳蛋白(N蛋白)对 Ⅲ 型 λ 干扰素(IFN-λ)的影响.创新点:首次在IPEC-J2细胞模型中证明PEDV流行病毒株的N蛋白可拮抗由聚肌胞苷酸(poly(I:C))诱导表达的 Ⅲ 型IFN,但不能拮抗 Ⅰ 型或 Ⅱ 型IFN.这种拮抗作用是通过阻断核因子 κB(NF-κB)入核来实现的.方法:利用poly(I:C)刺激IPEC-J2细胞使其IFN诱导表达.实验组转染N蛋白真核表达载体,对照组转染空载体;利用定量聚合酶链反应(qPCR)、荧光素酶报告基因等技术,检测N蛋白对 Ⅰ 型、Ⅱ型及 Ⅲ 型IFN表达抑制情况.利用间接免疫荧光技术,检测NF-κB在细胞内的分布情况,分析NF-κB入核与N蛋白抑制IFN-λ 表达的关系.结论:2013年至2017年间从浙江省不同的农场分离的10个PEDV毒株的N蛋白具有较高的核苷酸同源性,而疫苗毒株CV777的N蛋白在系统发育树中形成单系分支(图1).流行病毒株的N蛋白可以在IPEC-J2细胞中成功表达(图2和3),并拮抗由poly(I:C)诱导表达的 Ⅲ 型IFN,但不能拮抗 Ⅰ 型或 Ⅱ 型IFN(图4和5).PEDV N蛋白通过阻断NF-KB入核来对poly(I:C)诱导的IFN-λ3产生的抑制作用(图6).“,”Porcine epidemic diarrhea virus (PEDV) is a highly infectious pathogen that can cause severe diseases in pigs and result in enormous economic losses in the worldwide swine industry. Previous studies revealed that PEDV exhibits an obvious capacity for modulating interferon (IFN) signaling or expression. The newly discovered type Ⅲ IFN, which plays a crucial role in antiviral immunity, has strong antiviral activity against PEDV proliferation in IPEC-J2 cells. In this study, we aimed to investigate the effect of PEDV nucleocapsid (N) protein on type Ⅲ IFN-λ. We found that the N proteins of ten PEDV strains isolated between 2013 and 2017 from different local farms shared high nucleotide identities, while the N protein of the CV777 vaccine strain formed a monophyletic branch in the phylogenetic tree. The N protein of the epidemic strain could antagonize type Ⅲ IFN, but not type Ⅰ or type Ⅱ IFN expression induced by polyinosinic-polycytidylic acid (poly(I:C)) in IPEC-J2 cells. Subsequently, we demonstrated that the inhibition of poly(I:C)-induced IFN-λ3 production by PEDV N protein was dependent on the blocking of nuclear factor-κB (NF-κB) nuclear translocation. These findings might help increase understanding of the pathogenesis of PEDV and its mechanisms for evading the host immune response.