The Identification Of Viral Pathogen And Preliminary Study Of Viral Characteristics On The Necrosis Hepatitis Of The Muscovy Duck

A new infectious disease characterized by high morbidity, high mortality weak foot, head stringing and lots of white necrotic spots in liver and spleen occurred in Fujian, Zhejiang, and Guangdong province since 1998.Etiological study of the diseased ducks was carried out, three strains of viruses were isolated from the livers and spleens of the diseased moscovy ducks by our laboratory, one of which was used to be identified.Based on experimental infections, the result suggested that moscovy ducks be susceptible to the virus whereas chickens, ducks and geese be refractory. The virus was adapted to muscovy duck embryo system. (MES) on which the virus was lethal to embryos or induced cytopathic effect (CPE) on muscovy embryo fibroblast (MEF). The MES-adapted could not produce identical CPE on duck embryo fibroblast (DEF), chicken embryo fibroblast (CEF) and goose embryo fibroblast (GEF). Antisecum from the virus infected muscovy ducks specifically prohibited the production of CPE. The viral nucleic acid in the nucleus of infected cells showed up yellow green after stained with acridine orange. The virus nuclease can be digested by DNase I , resist PvNase and S1 Nuclease .The virus was sensitive to ethyl ether, chloro form, trypsin and heat treatment. Its infectivity was completely lost at pH 5.0. There is no thermostabilization effect in the presence of IMMg2+.The virus could not agglutinate erythrocytes of chickens, ducks, geese, pigeons and human (type O). According to neutralization tests, it showed that the virus was antigenically distinguishable from DPV (duck plague virus), NDV (New Castle disease virus), DHV. (Duck hepatitis virus).In ultrathin sections of infected muscovy ducks' lives, viral particles with diameter of approximately 80-120nm could be observed in spherical or elliptical in outline .By negatively staining, virions appeared circular or irregular. The envelope was very easily damaged or wrenched.On the basis of its morphology, size, chemophysical and biological characters and nucleic acid type, the virus was categorized into Herpesviridae.