The Isolation And Identification Of Duck Avian Reovirus

Avian reovirus exists in many kinds of birds. Chickens,Muscovy ducks and ducks infected by avian reovirus would be with disease. While, disease induced by avian reovirus was diversification and anabatic. So economic loss cased by avian reovirus, are damaging avian cultural industry in many country. In 2006, there had been a new acute infectious disease in some duck nurseries in Hubei province. There were many white necrotic lesions on the spleen of duck infected. Morbidity rate was 100% and mortality rate was 40%. Through serum neutralization test, RT-PCR and so on, this research certified that pathogen was avian reovirus.Clinical symptom and pathological change were observed. Infected ducks had phenomenon of diarrhea and dacryorrhea. After dissecting dead ducks, there were many white plaques in the surface of spleen of dead duck. And liver became white and reticulate. The result of histopathologic examination was as below: There were some focuses of necrosis in spleen. Cellular necrosis took place in the focuses. And heterophile granulocytes infiltrated in the focus of the spleen. Nucleolus of hepatocyte became disappeared. There were many eosinophile granulocytes and macrophages in the spleen, which observed by transmission electron microscope.When duck embryo was inoculated through allantoic cavity, one strain of virus was obtained. The ELD50 was 10^-5.75. This strain could also infect duck embryo desmocyte, and the TCID50 was 10^-4.42. It was displayed through neutralization test, this strain of virus could be neutralized by avian reovirus positive serum.Pathogenicity and physico-chemical property of had been known. The virion was round, non-peplos. And its diameter was about 70nm. This strain of avian reovirus was resistive with heat,ethylether and acid. It could hold activity after staying at 65℃for one hour. This strain could not agglutinate gallinaceous akaryocyte, so it had no compendency.S2 gene order of the virus was determined. Length of S2 gene was 1123bp. Homology between this strain of reovirus and Muscovy duck reovirus was 93%, while it between this strain of reovirus and duck reovirus was 97%.It was certificated by all above that the pathogen causing this disease was avian reovirus.