为观察肥大细胞（Mast Cell, MC）在vvIBDV感染中的作用，将60只30日龄无病原感染（Specific Pathogen Free， SPF）鸡随机分成感染组和对照组。感染组经滴鼻、点眼、肛拭感染超强毒株传染性法氏囊病病毒（very virulent Infectious Bursal Disease Virus, vvIBDV）于0，24，48和72 h后，分别取法氏囊、胸腺、脾脏，用甲苯胺蓝染色法观察上述各组织中的MC数量的动态变化；用免疫组化染色法检测各组织中IBDV病毒抗原和5-HT分布量的动态变化。结果表明：与对照组相比，感染组鸡各免疫器官中，MC的数量随着病毒分布量的增加和组织损伤程度的加重而明显增多（P<0.01）；MC释放的介质之一——5-HT的量也明显增多（P<0.01）。由此推断，MC和5-HT参与了IBD的发病过程，它们在IBDV感染引起的免疫器官严重损伤中可能起着重要的作用。

In order to study the potential role of mast cells in Special Pathogens Free(SPF) chickens infected by the very virulent Infectious Bursal Disease Virus (vvIBDV), 60 SPF chickens of 30 days of age were randomly divided into two groups(control group and vvIBDV tested group). The chickens in the tested group were innoculated with vvIBDV through nosedrop, eyedrop and anusrub. Bursa of Fabricious, thymus and spleen were taken at 0, 24, 48, 72 hpi(hours post-infection). The dynamic change of mast cell was tested by improved Toluidine Blue(TB) staining. The quantity change of vvIBDV viral antigen and 5-HT in tissues were tested by immunohistochemistry. The results show: ① vvIBDV viral antigen is extensively distributed in thethymus, spleen, and bursa of Fabricious, however, the localization of vvIBDV viral antigen is different in different tissues and organs. Obviously, the positive substance of vvIBDV viral antigen in the experimental group enhances the inflammatory reaction in the major immune organs such as bursa of Fabricius, spleen and thymus. ② The number of mast cells obviously increases in the experimental group (P＜0.01) after vvIBDV infection. Compared with the control group, the mast cells gradually increase from 24 hpi to 48 hpi and 72 hpi (P＜0.05). And few mast cells could be found in the bursa，thymus and spleen of control group. ③ 5-HT, the product of mast cells, is distributed in the tissues according to the mast cells' distribution. The result suggests that mast cells and 5-HT participate in the infectious process of vvIBDV.