高抗体水平下H9N2亚型禽流感病毒对鸭的致病性

H9N2-AIV on pathogenicity on ducks with the high titer of antibody

将60只种鸭免疫接种H9N2灭活疫苗,在高抗体水平下,通过点眼、滴鼻、气管注射3种接种途径人工感染300日龄种鸭,观察种鸭的发病情况、症状及剖检变化;于感染后3、6、9d采血进行血液生化指标检测;利用建立的RT-PCR方法检测各试验组和对照组的带毒情况;采集输卵管、肝脏、肺脏和气管等组织固定、切片、HE染色,观察各器官病理组织学变化;利用建立的IFA方法对H9N2在种鸭体内的分布进行研究。结果显示,3组接种H9N2亚型禽流感后,引起种鸭采食下降、流泪、排白色稀便等症状;总蛋白(TP)、谷丙转氨酶(ALT)、谷草转氨酶(AST)和碱性磷酸酶(AKP)的含量发生了显著变化;病理组织学变化以肝脏颗粒变性和空泡变性,肺脏广泛性出血和炎性细胞浸润,输卵管纤维蛋白渗出为特征;IFA阳性信号主要分布于气管、输卵管、肺脏、肝脏和胰腺等处;对照组精神状态良好,各项生理指标趋于正常,IFA未检测到阳性信号。结果表明,在高抗体水平下,H9N2亚型禽流感病毒也可通过眼结膜、鼻腔黏膜、气管黏膜等侵入机体导致鸭的发病。

60 ducks were vaccinated with H9N2 inactivated vaccine,The ducks with the age of 300 days were artificially infected through the eyedrops,dripping from nose and tracheal injection in the high titer antibody,the incidence,change of autopsy clinical symptoms of ducks were observed.Their bloods were collected to be carried out the detection of blood parameters after infection at the 3,6,9 day,observation of detoxification conditions of the experimental group and negative control group were done using the established RT-PCR detection methods.The fallopian tube,liver,lung trachea and so on were collected to be fixed and cut sheet by conventional HE staining.Then the histopathological changes of these organs were observed.The distribution of the H9N2-AIV in ducks issue was studied with IFA（indirect fluorescent antibody test）;three experimental groups were caused lower ingestation,shedding tears,defecating white loose stools and other symptoms.The content of total protein（TP）,glutamate pyruvate transaminase（ALT）,glutamic-oxal（o）acetic transaminase（AST）and alkaline phosphatase（AKP）significantly changed after infection.Histopathological changes were characterized by granular degeneration and vacuolar degeneration in the liver,catholicity hemorrhage in the lungs,inflammatory cell infiltration and fiber protein exudate from the fallopian tube.IFA positive signals were mainly distributed in the trachea,fallopian tube,lungs,liver and pancreas.But the spirit of ducks was very fine,all physiological indexes were close to normal,positive signals were not detected by IFA in the control group.Even in the high titer of antibody,H9N2-AIV invades organism to fall ill by eye,nose,trachea and other local mucous membrane.