College of Animal Science, Fujian Agriculture and Forestry University, Fuzhou 350002, People's Republic of China; Fujian Key Laboratory of Traditional Chinese Veterinary Medicine and Animal Health, Fujian Agricultural and Forestry University, Fuzhou 350002, People's Republic of China.
College of Animal Science, Fujian Agriculture and Forestry University, Fuzhou 350002, People's Republic of China.
Poult Sci. 2021 Jan;100(1):64-72. doi: 10.1016/j.psj.2020.10.021. Epub 2020 Oct 14.
Muscovy duck reovirus (MDRV) infection induces serious immunosuppression and intestinal injury in Muscovy ducklings with a high morbidity and mortality, and Astragalus polysaccharide (APS) pretreatment could efficiently protect ducklings from MDRV infection, although the underlying immunoregulatory mechanisms remain unclear. Thus, the objective of this study was to investigate effects of APS on the intestinal mucosal immunity in MDRV-infected Muscovy ducklings. A total of 190 1-day-old healthy Muscovy ducklings were randomly assigned to 3 groups (n = 50): normal control group, APS pretreatment for MDRV-infected group, and cohabitation infection group, then pretreated with 0.6 g/L APS or only drinking water followed by MDRV cohabitation infection with the remaining 40 artificially infected ducklings, respectively. At the 2, 3, 4, 6, 9 and 15 d after cohabitation infection, the intestinal samples were prepared to measure intestinal parameters including villus length, villus length/crypt depth (V/C) ratio, and wall thickness, together with counts of intraepithelial lymphocyte (IEL) and goblet cell (GC) by hematoxylin-eosin staining. Meanwhile, ileal secretory IgA (sIgA) and duodenal cytokine levels of IL-4, IL-6, IL-15, tumor necrosis factor-alpha, and interferon gamma were detected by the ELISA and radioimmunoassay, respectively. The results showed that APS significantly improved intestinal injuries of villi length, V/C ratio, and wall thickness of the small intestine infected with MDRV, effectively inhibited the reduction of IEL and GC caused by MDRV infection, subsequently increased sIgA and all the cytokine secretions at most time points, suggesting that APS pretreatment can effectively stimulate mucosal immune function by improving intestinal morphology and repair MDRV caused injures of small intestinal mucosal immune barrier in infected ducklings. Our findings lay the foundation for further application of APS in prevention and treatment of MDRV infection.
鸭呼肠孤病毒（Muscovy duck reovirus，MDRV）感染可导致番鸭严重免疫抑制和肠道损伤，发病率和死亡率高，黄芪多糖（Astragalus polysaccharide，APS）预处理可有效保护番鸭免受 MDRV 感染，但潜在的免疫调节机制尚不清楚。因此，本研究旨在探讨 APS 对 MDRV 感染番鸭肠道黏膜免疫的影响。将 190 只 1 日龄健康番鸭随机分为 3 组（n = 50）：正常对照组、APS 预处理+MDRV 感染组和同居感染组，分别用 0.6 g/L APS 或仅饮水预处理，然后用剩余的 40 只人工感染番鸭进行 MDRV 同居感染。同居感染后第 2、3、4、6、9 和 15 天，制备肠道样品，通过苏木精-伊红染色测量肠道参数，包括绒毛长度、绒毛长度/隐窝深度（V/C）比值和壁厚度，同时计数上皮内淋巴细胞（IEL）和杯状细胞（GC）。同时，通过酶联免疫吸附试验和放射免疫分析检测回肠分泌型免疫球蛋白 A（secretory IgA，sIgA）和十二指肠白细胞介素（IL）-4、IL-6、IL-15、肿瘤坏死因子-α和干扰素-γ等细胞因子水平。结果表明，APS 显著改善了 MDRV 感染的小肠绒毛长度、V/C 比值和壁厚度等肠道损伤，有效抑制了 MDRV 感染引起的 IEL 和 GC 减少，随后在大多数时间点增加了 sIgA 和所有细胞因子的分泌，提示 APS 预处理可通过改善肠道形态和修复 MDRV 引起的感染雏鸭小肠黏膜免疫屏障损伤，有效刺激黏膜免疫功能。本研究为 APS 在预防和治疗 MDRV 感染中的进一步应用奠定了基础。
