| The disease is a new viral infectious disease which infects goslings in JiangSu Province in 2001. The diseased goslings showed characteristic hemorrhagic necrotic hepatitis. Two strains viruses were isolated from the livers and spleens with lots of gray-yellow local necroses of goslings by our laboratory, one of which was identified as avian reovirus.The general hemorrhagic and gray-yellow necrotic foci were observed on the surface of liver and spleen of the dead embryos of chickens,ducks or geese inoculated by the way of allantoic membrane with the goose reovirus isolate LY01-3G However, the virus did not grow well when they were inoculated to the allantoic cavity of embryos. The LY01-3G isolated virus produced some cytopathic effects(CPE) on the chicken or goose embryo fibroblast cell which formed the rounded cells, granular degeneration, and then lysis. But in duck embryo fibroblast cell, the cytopathic changes were always less characteristic. The goslings could be infected with the reovirus isolate LY01-3G by intramuscular(i.m.) or pad injection. The pathologies of died goose were similar to those of field cases, and the virus was recovered. There were inflammatory responses caused by the pad inoculation to the one-day-old chickens, though the apparent clinical signs did not appear by i.m.injection on chickens. The liver, spleen, pancreas, kidney and brain of died goose were made out pathologic slices. Antiserum from the geese infected by the virus specifically prohibited the production of CPE.The viral nucleic acid of infected cells showed yellow-green fluorescence afterstained with acridine orange. The virus isolate was proved to be resistant to 5-BUDR, aether, chloroform, trypsin, heat and acid treatment, and failed to agglutinate red blood cells of chicken, duck, goose, rabbit and goat. There is thermostabilization effect in the presence of 1M Mg2+. According to neutralization tests, it showed that the virus was antigenically distinguishable from GPV(Goose Plague Virus), NDV(New Castle Disease), AIV(Avian Influenza Virus), and it had certain antigen correlation with avian reovirus by acrossing AGP.The virus in the allantoic fluids dealt with the technology of ion exchange capture showed spherical, no envelope, having double-deck capsids, with outer-capsid of 75nm in diameter, with inner-capsid of 50nm in diameter. The ultrathin sections which were made out from the embryo livers were observed by TEM, the results suggested that the virus replicate in cytoplasm, no envelope, with diameter of approximately 80nm.According to virus-isolation,experimental infection, electromicroscope observation and nucleic acid detection, the virus strain was identified as one number of the family reoviridae. In addition, physicochemical and biological properties showed that the isolated LYoi-aG has basic characters of avian reovirus , so the virus strain was categorized into avian reovirus.On the basis of the identification of viral pathogen, we established a method of the agar gel precipitin(AGP) test to detect antigen or antibody of the gosling hemorrhagic necrotic hepatitis. The positive percentages in liver antigen or antiserum of infected goslings were 70% or 60% and the highest litres of AGP were 25 or 24. AGP test is a simple, higher specific and sensitive, easy to judge method for detecting antigen or antibody to gosling hemorrhagic necrotic hepatitis. |
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