适应肠道细胞的猪德尔塔冠状病毒对仔猪的致病性分析

The pathogenicity of the intestinal cell-adapted porcine deltacoronavirus to piglets

为分析适应肠道细胞的猪德尔塔冠状病毒(Porcine deltacoronavirus,PDCoV)对仔猪的致病性,本研究首先用ST细胞分离培养的PDCoV感染IPEC-J2细胞进行适应性试验,通过间接免疫荧光试验(IFA)检测PDCoV抗原,然后绘制病毒生长曲线,最后分析适应IPEC-J2细胞的PDCoV对仔猪的致病性。结果表明:1)经ST细胞分离培养的PDCoV可以感染IPEC-J2细胞并出现CPE,可在细胞内检测到PDCoV抗原,PDCoV在感染IPEC-J2细胞后48 h达到增殖高峰。2)适应IPEC-J2的PDCoV对仔猪具有肠致病性,仔猪出现明显腹泻症状,甚至出现死亡;剖检可见明显的肠道病变,病理组织学显示肠上皮细胞及肠绒毛病变,并通过免疫组化对抗原进行定位,发现PDCoV广泛分布于肠道上皮细胞。3)肠道免疫细胞因子分析发现PDCoV感染仔猪后肠道I型干扰素表达上调,同时激活体内Th1和Th2型肠道细胞免疫反应,诱导感染仔猪产生免疫细胞因子发挥抗病毒作用。综上,经ST细胞分离培养的PDCoV对IPEC-J2细胞具有较强的适应性,并对仔猪产生较强的致病性。本研究为PDCoV致病机制及抗病毒免疫进一步研究奠定基础。

To analyze the pathogenicity of the Porcine deltacoronavirus(PDCoV)adapted to intestinal cells in piglets,the IPEC-J2 cells were infected with PDCoV which was isolated from ST cells for adaptability testing.The PDCoV antigen was detected by indirect immunofluorescent assay(IFA),and then the virus growth curve was plotted.Finally,the pathogenicity of PDCoV adapted to IPEC-J2 cells in piglets was analyzed.The results showed that:1)PDCoV isolated from ST cells could infect IPEC-J2 cells with CPEs and PDCoV antigen could be detected within the cells.PDCoV reached its proliferation peak at 48 hours after infecting IPEC-J2 cells.2)PDCoV adapted to IPEC-J2 had intestinal pathogenicity in piglets,causing significant diarrhea symptoms and even death.Obvious intestinal histopathologic lesions were observed,and histopathological examination revealed lesions in intestinal epithelial cells and villi,and the antigen was localized in the intestinal epithelial cells by immunohistochemistry.3)Gut immune cytokine analysis revealed that the type I interferon expression was upregulated after PDCoV infection in piglets.Both Th1 and Th2 type intestinal cell immune responses were activated simultaneously,inducing the production of immune cytokines in infected piglets to exert antiviral effects.Taken together,PDCoV isolated from ST cells,has strong adaptability to IPEC-J2 cells,and exhibits strong intestinal pathogenicity in piglets.The study lays the foundation for further research on the pathogenic mechanism and antiviral immunity of PDCoV.