鸡传染性支气管炎病理形态学及发病机理的研究

STUDIES ON THE PATHOMORPHOLOGY AND PATHOGENESIS OF AVIAN IB

150只18日龄雏鸡随机分为两组,试验组90只接种传染性支气管炎病毒(IBV-M_(41))后35天内分30批依次于不同时间扑杀,作组织病理学、超微结构及病毒抗原定位检查,对照组60只作相同的检查。结果表明,IBV攻击的靶器官是气管,气管的病变表现为粘膜上皮细胞的损伤和脱落、残留的上皮细胞增殖形成复层上皮、粘膜固有层及粘膜下层大量淋巴细胞浸润及粘膜逐渐恢复的相互连续的病理过程。肺脏初级、次级支气管也有类似的变化。气管粘膜的超微结构变化为上皮细胞的纤毛脱落,胞浆内有病毒粒子,3～5成群外被内质网膜,通过出芽方式释放,病毒在上皮细胞内复制,可直接导致上皮细胞的损伤。经呼吸道感染时,病毒抗原首先在气管粘膜上皮细胞中出现,并在其中复制,其病毒含量最高,持续存在时间最长,向全身播散后,主要在与病毒有亲和性的肺和肾脏中繁殖,而心、肝、脾仅有一过性少量病毒。

In order to study the pathomorphology and pathogenesis of infectious bronchitis (IB), 18-day-old chickens were artificially inoculated with IBV-M41 and the methods of histology, immunofluorescence, electron microscopy were used for investigating the pathological changes, localization of IBV antigen after inoculation for 35 days. The results showed: l) IBV mainly injured the respiratory tract, and the pathological changes of trachea were the most serious; pulmonary lesions were generally mild, only slight microscopical changes of kidney might be detected in individual cases, therefore the trachea was the major target organ of IBV infection. 2) Under the direct injury of IBV, there were pathological processes in sequence in trachea, it included the damage and desquamation of epithelial cells, the proliferation of residual cells and the formation of stratified epithelium, obvious lymphocytic infiltration in the lamina propria and submu-cosa, and recovery of mucosa. 3) When infection via the respiratory tract, viral antigen first appeared in mucosal epithelial cells of the trachea, the virus replicated in the epithelial cells, there were the most quantity and persistent time of IBV in tracheal mucosa; while spreading IBV maily distributed in the lungs and kidney which had affinity for IBV, only transient and a few IBV might be detected in the heart, liver and spleen etc. 4) The ultrastructural changes of tracheal mucosa included the loss of cilia, viral particles 3-5 in a group in the cytoplasm of ciliated epithelial cells, releasing by budding through the membrane of endoplasmic reticulum, striking lesions of cell organells; The replication of IBV in the epithelial cells might directly result in the damage of cells.