1株QX型鸡传染性支气管炎病毒的S1基因序列分析及致病性研究

S1 gene sequence analysis and pathogenicity study of a QX-type avian infectious bronchitis virus

为跟踪鸡传染性支气管炎病毒(IBV)的流行及致病特性,2020年从安徽某蛋鸡场采集的发病鸡气管和肾脏组织中分离到1株病毒,对其进行生物学特性鉴定及致病性分析,确定该毒株为IBV,并命名为CK/CH/LAH/20-6。分离毒株可引起鸡胚发育受阻,呈现侏儒胚、蜷缩胚等特征性病变;S1基因检测及遗传演化分析表明,S1基因大小为1 620 bp,属于QX型毒株,与华南地区CK/CH/SHD/GM17-1分离株S1基因同源性高达99.9%;14日龄SPF雏鸡致病性试验结果表明,分离毒株可致雏鸡100%(20/20)发病,20%(4/20)死亡,同时可致气管和肾脏出现不同程度的病理损伤;排毒检测结果表明,攻毒鸡第3天气管及泄殖腔排毒检测率分别为95%(19/20)和85%(17/20),第21天排毒检测率仍达81.25%(13/16)和75%(12/16)。本研究为鸡传染性支气管炎的防控提供了新的流行病学数据,丰富了IBV的生物信息数据库。

To investigate the prevalence and pathogenicity of the avian infectious bronchitis virus(IBV), an IBV strain was isolated from the trachea and kidney tissues of infected chickens from a layer farm in Anhui Province in 2020, and the biological characteristics and pathogenicity of the strain were analyzed, and the strain was identified as an IBV and named CK/CH/LAH/20-6. The chicken embryo was hindered and showed characteristic lesions such as dwarf embryos and curled-up embryos, which was caused by the strain. The results showed that the S1 gene of the strain was 1 620 bp, which belonged to the QX type and it had 99.9% homology with the isolated strains CK/CH/SHD/GM17 in South China. The results of the pathogenicity test showed that the virus caused 100%(20/20) morbidity and 20%(4/20) mortality of 14-day-old SPF chicks. At the same time, it caused different degrees of pathological damage to the trachea and kidneys of the birds. The virus excretion test showed that the virus was excreted in the trachea and cloaca of the experimental chickens on the 3 rd day after they were challenged with the strain. The virus detection rates were 95%(19/20) and 85%(17/20), respectively, and the virus detection rates were as high as 81.25%(13/16) and 75%(13/16) on the 21 st day after the challenge. This study provided new epidemiological data for the prevention and control of avian infectious bronchitis virus, and enriched the biological information database of IBV.