一例肉鸡传染性支气管炎与H9亚型禽流感混合感染的病例分析

A case analysis of a mixed infection of infectious bronchitis and H9 subtype avian influenza in broiler chickens

2023年山东某鸡场部分肉鸡发生不同程度的呼吸困难,并伴有零星死亡,死鸡剖检可见气管出血、支气管栓塞、部分鸡有尿酸盐沉积。为探究其发病原因,采集病料进行了常见呼吸道病原的PCR检测。结果显示,此鸡场呼吸道传染病是由禽传染性支气管炎病毒(Infectious Bronchitis virus,IBV)与H9亚型禽流感病毒(Avian Influenza virus,AIV)混合感染引起。病料经分离纯化后分别获得一株IBV分离株(SDDZ/202301简称DZ01)和一株H9亚型AIV分离株(SDDZ/202302简称DZ02)。分别对DZ01的S1基因和DZ02的HA基因扩增,测序结果发现,DZ01与参考株核苷酸和氨基酸同源性分别为60.2%~96.7%和50.3%~95.6%,确定为GI-19基因型,与同型参考株相比有13个氨基酸发生点突变,裂解位点为HRRRR,并发现15个N-糖基化位点。AIV H9同源性分析显示DZ02与参考株核苷酸和氨基酸同源性为78.1%~95.1%和79.4%~94.2%,为H9.4.2.5分支,属于山东省内优势毒株。本研究明确了该养殖场中出现了IBV和H9亚型AIV的混合感染,这表明该养殖场仍需加强生物安全管理等方面的工作。

Some broilers in a chicken farm in Shandong Province showed varying degrees of respiratory distress and sporadic deaths in 2023.Autopsy of dead chickens showed tracheal haemorrhage,bronchial embolism,and urate deposits in some chickens.In order to investigate the cause of the disease,diseased material was collected for PCR testing of common respiratory pathogens.The results showed that the respiratory tract infections in this chicken farm were caused by a mixed infection of Infectious Bronchitis virus(IBV)and Avian Influenza virus(AIV)subtype H9.After isolation and purification,an IBV isolate(SDDZ/202301 abbreviated as DZ01)and an H9 subtype AIV isolate(SDDZ/202302 abbreviated as DZ02)were obtained.The S1 gene of DZO1 and the HA gene of DZ02 were amplified respectively,and the sequencing results revealed that the nucleotide and amino acid homology between DZO1l and the reference strain ranged from 60.2%-96.7%and 50.3%-95.6%,respectively,and it was determined to be the GI-19 genotype,with 13 amino acid point mutations compared with the homozygous reference strain,and the cleavage site was HRRRR,and 15 N-glycosylation sites were found.The homology analysis of AIV H9 showed that the nucleotide and amino acid homology between DZ02 and the reference strain was 78.1%-95.1%and 79.4%-94.2%,and it was the H9.4.2.5 branch,which was the dominant strain in Shandong Province.In this study,mixed infections of IBV and AIV H9 occurred in this chicken farm,indicating that this farm still needs to strengthen biosecurity management and other aspects.