鸡传染性支气管炎病毒MM41株感染雏鸡的组织病理学研究

Study on Histopathological Changes of Chicks Infected with Infectious Bronchitis Virus M41 Strain

为全面了解鸡传染性支气管炎病毒（IBV）感染引起雏鸡多个器官组织病理损伤情况,研究对IBV M41株人工感染SPF雏鸡后不同时间的气管、肺脏、肾脏、哈德氏腺、胸腺、法氏囊、脾脏、肝脏、胰腺和十二指肠进行病理组织学变化观察,同时应用实时荧光定量PCR方法对气管和肾脏中IBV载量进行检测。结果显示,IBV M41株主要侵害鸡呼吸器官气管和肺脏,分别在感染后第1、3天开始出现病变并持续2~3周。肾脏主要表现为肾小管上皮细胞轻度变性和少量淋巴细胞浸润,从第5天持续到第28天。感染后第5天,免疫器官哈德氏腺、胸腺和法氏囊开始出现不同程度的细胞变性,其中哈德氏腺最严重。感染后第3~21天,脾脏白髓面积增大,局部出现少量异嗜性细胞,病变轻微。感染5 d后,肝脏、胰腺和十二指肠先后出现轻度细胞变性,少量淋巴细胞浸润,持续到第28天。感染后第1~11天气管和肾脏病毒载量维持较高水平,分别在第5、8天达到峰值,气管病毒载量较肾脏高。结果表明,IBV M41株主要侵害鸡呼吸系统,对泌尿、免疫和消化系统也有亲嗜性;不同器官组织损伤程度和持续时间存在差异;气管和肾脏的病毒载量与组织损伤存在相关性。研究首次对IBV M41株感染雏鸡进行系统的组织病理学观察,为了解疾病发展过程、IBV致病机理和病理学诊断提供参考。

In order to have a comprehensive information on histopathological changes of chicks infected with infectious bronchitis virus （IBV）, SPF chicks were infected with IBV M41 strain artificially, and the trachea, lung, kidney, Harderian gland, thymus, Fabricius, spleen, liver, pancreas and duodenum of infected chicks were collected to make pathological section for observing histopathological changes at different time after infection. At the same time, real-time fluorescence quantification method was used to detect the viral load in trachea and kidney. The results showed that IBV M41 strain mainly injured the respiratory organs trachea and lung, they showed lesion on 1 and 3 day post infection （DPI） respectively and lasted 2 to 3 weeks. The kidney showed mild degeneration of renal tubular epithelial cells and lymphocyte infiltration between 5 DPI to 28 DPI. Variable degrees of cellular degeneration were seen in the immune organs including Harderian gland, thymus and Fabricius on 5 DPI, and Harderian gland had the most serious injury. Between 3 DPI and 21 DPI, the area of spleen＇s white pulp became bigger and little heterophilic granulocyte appeared in part of the tissue, and the histological change was slight. On 5 DPI, digestive organs including liver,pancreas and duodenum showed both histocyte degeneration and lymphocyte infiltration,and they lasted to 28 DPI. The virus loads in the trachea and kidney kept a high level between 1 DPI and 11 DPI,and reached the peak on 5 DPI and 8 DPI respectively. And the viral load in the trachea was higher than that in the kidney. In conclusion, IBV M41 strain mainly injured respiratory system of chicks,and had tissue tropism for immune, digestive and urinay organ;the degree and lasting time of lesions varied in different organs and tissues;there were relationship between histopathologieal change of the organs and the viral load in trachea and kidney. It＇s observed systematically the histopathology changes of multiple organs of chicks infected with IBV for the first time and it would provide a good reference for understanding the disease progress,IBV pathogenesis and pathological diagnosis.