Abstract: 【Objective】Previous studies showed that avian reovirus could infect vertically through egg, and avian reovirus can cause avian viral arthritis, respiratory and intestinal disease, myocarditis, hepatitis, immune suppression and so on. HP080421 strain of duck reovirus(DRV) isolated in the authors’ laboratory can cause soft duck feet as the main clinical features, and sick duck showed that a lot of white necrotic stove was on the surface of liver and spleen, and also kidney swelling and bleeding as the main pathological features. In this study, the pathogenicity of DRV to chicken embryo was investigated and whether the isolated HP080421 strain could infect chickens through the pathological changes of chicken was discussed, in order to provide a theoretical basis for the prevention and control of DRV infection.【Method】The infection model of SPF chicken to DRV was established through allantoic cavity inoculation SPF chicken embryos by using the isolated and identified HP080421 strains of DRV isolated in the lab. After chicks hatched from embryos, pathological examination methods such as clinical observation, pathological section examination, HE staining and immunohistochemical staining were used to study the pathobiology and pathogenicity of the SPF chicken embryo infected by DRV.【Result】Clinical observation found that chicken embryos were able to peck the shell after 22 - 23 days, but could not go out from the eggshell by themselves compared to the control group. At necropsy, liver and spleen were breakable and slightly swelling, many different size and yellow-white necrotic foci were consistently observed in the spleen and liver of the experimental group; the brain tissue was slightly swelling with few bleeding spots covered on it. Histopathological examination of H.E staining revealed necrotic foci in spleen and liver, which consisted of a necrotic center with lymphocytes infiltration at the periphery; in the Bursa of Fabricus, as well as in the thymus, lymphocyte depletion was apparent and cavities had developed in medulla. Besides, other organs such as lung, brain and kidney, showed different degrees of congestion and edema. Immunohistochemical detection showed that liver, lung, spleen and bursa of fabriciusa had positive signals, and were located in the cytoplasm and nucleus of epithelial cells and macrophages.【Conclusion】The results showed that the virus strain HP08421 could infect SPF chicken embryo and cause some specific pathologic changes. The pathological changes mainly focus on the liver and lymphoid organs, so DRV can be infected by vertical transmission of chickens, and can also lead to immune suppression. This study has expounded the possibility of infection of chickens by DRV, through the infection model of SPF chicken to DRV, as a matter of fact, in the actual process of production, farmers should prevent chicken embryo pollution by DRV to cut off the route of transmission, to achieve the purpose of preventing DRV infection.

Key words: duck reovirus, SPF chicken embryo, necropsy, immune organs, hematoxylin-eosin staining