Shi Fengyang, Li Qiuming, Zou Zhanming, Wang Yang, Hou Xiaolin, Zhang Yonghong, Song Qinye, Zhou Shuanghai, Li Huanrong
College of Animal Science and Technology, Beijing University of Agriculture, Beijing 102206, China.
College of Animal Science and Technology, Hebei Agricultural University, Baoding 071000, China.
J Vet Sci. 2020 Sep;21(5):e78. doi: 10.4142/jvs.2020.21.e78.
Enteritis is one of the most frequently reported symptoms in piglets infected with porcine circovirus type 2 (PCV2), but the immunopathogenesis has not been reported.
This study examined the effect of a PCV2 infection on the intestinal mucosal immune function through morphological observations and immune-related molecular detection.
Morphological changes within the ileum of piglets during a PCV2 infection were observed. The expression of the related-molecules was analyzed using a gene chip. The immunocyte subsets were analyzed by flow cytometry. The secretory immunoglobulin A (SIgA) content was analyzed by enzyme-linked immunosorbent assay.
The PCV2 infection caused ileal villus damage, intestinal epithelial cells exfoliation, and an increase in lymphocytes in the lamina propria at 21 days post-infection. Differentially expressed genes occurred in the defense response, inflammatory response, and the complement and coagulation cascade reactions. Most of them were downregulated significantly at the induction site and upregulated at the effector site. The genes associated with SIgA production were downregulated significantly at the induction site. In contrast, the expression of the Toll-like receptor-related genes was upregulated significantly at the effector site. The frequencies of dendritic cells, B cells, and CD8⁺T cells were upregulated at the 2 sites. The SIgA content decreased significantly in the ileal mucosa.
PCV2 infections can cause damage to the ileum that is associated with changes in immune-related gene expression, immune-related cell subsets, and SIgA production. These findings elucidated the molecular changes in the ileum after a PCV2 infection from the perspective of intestinal mucosal immunity, which provides insights into a further study for PCV2-induced enteritis.
肠炎是感染猪圆环病毒2型（PCV2）的仔猪中最常报告的症状之一，但免疫发病机制尚未见报道。
本研究通过形态学观察和免疫相关分子检测，研究PCV2感染对肠道黏膜免疫功能的影响。
观察PCV2感染期间仔猪回肠的形态学变化。使用基因芯片分析相关分子的表达。通过流式细胞术分析免疫细胞亚群。采用酶联免疫吸附测定法分析分泌型免疫球蛋白A（SIgA）含量。
PCV2感染导致感染后21天回肠绒毛损伤、肠上皮细胞脱落和固有层淋巴细胞增多。在防御反应、炎症反应以及补体和凝血级联反应中出现差异表达基因。其中大多数在诱导部位显著下调，在效应部位上调。与SIgA产生相关的基因在诱导部位显著下调。相反，Toll样受体相关基因的表达在效应部位显著上调。两个部位的树突状细胞、B细胞和CD8⁺T细胞频率均上调。回肠黏膜中SIgA含量显著降低。
PCV2感染可导致回肠损伤，这与免疫相关基因表达、免疫相关细胞亚群和SIgA产生的变化有关。这些发现从肠道黏膜免疫的角度阐明了PCV2感染后回肠的分子变化，为进一步研究PCV2诱导的肠炎提供了思路。
