Abstract: In this study, GX-08 strain was selected to perform virus infection test on 26 d chickens and 20 d muscovy ducks at the dose of 10^5.5EID₅₀.The morbility and mortality of chickens infected with viruses through intramuscular route were 100% and 100%, 70% and 70% for muscovy ducks. The morbility and mortality of chicken infected with viruses through both oral and oculonasal routes were 80% and 30%, 20% and 20% in muscovy ducks. Pathological changes of digestive tract and some respiratory tract of the infected chicken were severe, which was characterized as the infection of typical visceratonia ND. In comparison with slight pathological changes in digestive tract and some respiratory tract, obvious pathological change were observed in liver, spleen, pancreas etc. of muscovy ducks. It indicated that GX-08 strain had highly pathogenicity in ducks and chickens, causing systemic infections involving many organs and tissues in duck and chicken, and resulting in the invasion and death. In in vitro tests, cell lesions could be observed in both CEF monolayers and DEF monolayers inoculated with GX-08 strain at the dose of 200 TCID₅₀, and the cells were destroyed completely at about 96 and 84 h respectively. In comparison with CEFs, the cytopathic effect on DEFs infected with virus developed more rapidly, the number of syncytial cells and its nuclei were more, and the HA titer in the culture supernatants was higher. The results indicated that GX-08 strain could cause cytopathic effects to CEFs and DEFs, and induced stronger syncytium formation in DEFs than CEFs.

Key words: Newcastle disease virus; chicken; duck; pathological changes; cytopathic effect