新型H3N8亚型禽流感病毒分离鉴定与鸡致病性研究

为调查我国多个省份鸡群中发生一种以眼睑肿胀出血、呼吸道症状、产蛋鸡产蛋率急性下降为特征的传染性疾病的致病病原，本研究对发病鸡群进行流行病学调查，病原分离鉴定，病毒全基因序列分析，并对分离病毒进行了动物回归试验。结果表明:1)该病自2021年12月首先发现于广东省某三黄鸡群，随后陆续在福建、安徽、江苏、河南等多个省份鸡群中发生，鸡群发病率高，后期易继发感染细菌，死亡率1%~10%；2)实验室初步诊断为H3N8亚型禽流感；3)全基因组序列分析表明，该病毒为新型禽流感病毒，系欧亚禽分支H3基因、北美禽分支N8基因与G57基因型H9N2病毒内部基因组成的三源重排病毒；4)新型H3N8病毒对SPF鸡高度易感，感染鸡表现为眼睑肿胀出血，轻微呼吸道症状；病理变化为哈德氏腺黏膜坏死，鼻甲、气管纤毛上皮细胞坏死，黏膜下层炎性细胞浸润，肺脏支气管肺炎；病毒可通过口咽和泄殖腔排毒，排毒时间为5~7 d；病毒在鼻甲、气管和肺脏中可高效复制，并且可以在哈德氏腺等肺外脏器复制。综上，新型三源重排H3N8禽流感病毒对鸡高度适应，对呼吸系统致病性较强，应尽快开展系统的流行病学监测，及早对病毒的源头及传播途径进行防控，力争将这种新型病毒消灭在流行早期阶段。

Pathogenicity of novel reassortment H3N8 avian influenza A virus in chickens

An infectious disease characterized by eyelid swelling, respiratory symptoms and acute egg-laying rate decline in chicken flocks in multiple provinces of China. In order to explore the pathogen, epidemiological survey, virus isolation and identification, sequence analysis, and chicken infection experiment were analyzed. The results indicated: 1)In December 2021, this disease was firstly found in Three-yellow chicken flock in Guangdong Province, and then occurred in Fujian, Anhui, Jiangsu, Henan and other provinces, the chicken flocks that were exhibit high morbidity and easy to infection bacterial, the mortality rates range from 1% to 10%. 2)The pathogen was diagnosed as H3N8 subtype AIVs. 3)Sequence analysis showed that the novel H3N8 AIVs were evolving as a triple reassortment event with Eurasian avian H3 gene, North American avian N8 gene and G57 genotype H9N2 internal genes. 4)The new H3N8 AIVs were highly susceptible to SPF chickens. Infected chickens showed eyelid swelling and hyperemia, and mild respiratory symptoms. The pathological changes were necrosis and abscission of Harderian glands mucosa, necrosis of ciliated epithelial cells of turbinate and trachea, infiltration of inflammatory cells in submucosa, and bronchopneumonia of lungs. The virus can be detected from the oropharynx and cloaca for 5-7 days, and replicate efficiently in the concha nasalis, trachea and lungs, also in extra pulmonary organs such as Harders glands. In conclusion, the novel reassortment H3N8 virus was adapted to chickens and caused pathogenic in chickens. Therefore, comprehensive surveillance of the H3N8 AIVs in domestic poultry is imperative and control of the virus endemic is needed.