H5N1亚型禽流感病毒的鸭致病性研究

Pathogenicity of H5N1 Influenza Virus for Ducks

【目的】为了验证H5N1亚型禽流感病毒对鸭是否具有致病作用。【方法】对2003年某地方养鹅场发病鹅群分离的一株H5N1亚型流感病毒A/Goose/HLJ/QFY/2003的生物学特性和致病性进行研究。【结果】动物实验表明该病毒对不仅对鸡具有高致病性(IVPI=3),而且对鸭也具有高致病性。雏鸭人工感染该病毒后临床表现典型的神经症状,剖检可见脑膜点状出血,肝脾肿大并见有坏死灶,肺脏严重充血、出血,消化道粘膜弥散性出血。病理组织学检查发现全身各脏器以出血、充血、细胞变性坏死和炎性细胞浸润为主要特征,并表现为不同程度的损伤。感染鸭死亡集中在感染后的4～6d,致死率75%。雏鸭在病毒感染后2～4d的气管、泄殖腔及全身各主要器官均可分离到病毒。虽然攻毒后14d耐过鸭血清中可检测到1∶16的HI抗体;但是此时胰腺中仍然可分离到低水平的病毒。【结论】本研究继从野鸟分离到对鸭具有高致病性禽流感病毒之后,首次证实家禽中也存在对鸭具有高致病性的禽流感病毒流行。

The ducks are considered to be a natural reservoir for influenza viruses. Neither shows any clinical symptoms nor mortality when ducks infected with influenza virus. In order to assess the pathogenesis of the influenza A virus A/Goose/HU/QFY/03 （HSN1） isolated from a diseased geese farm, the SPF chickens and ducks were challenged by natural route, respectively. Challenge experiments demonstrated that the isolate was highly pathogenic both to chickens （IVPI=3） and ducks where it produced 75% mortality. Depression and marked nerologic dysfunction were common clinical manifestations of disease. Gross lesions included liver and splenomegly, hemorrhages; lung with severe acute congestion and hemorrhages; diffused enteric mucosa hemorrhages in alimentary tract. Histologic lesions were observed in multiple parenchymal organs and were characterized by congestion, hemorrhage, degeneration to necrosis or heterophilis infliltration. High titers of viruses were isolated from tracheal and cloacal swabs as well as multiple organs by 2-4 DPI （days post infection）, and the viruses were confined only to pancreas after 7 DPI. This is the first confirmed HSNlvirus isolated from domestic poultry that are lethal to ducks.