Isolation And Pathogenicity Analysis Of An Avianpox Virus Isolated From An Wild Oriental Turtle Dove (Streptopelia Orientalis)

Avipoxviruses (APVs) belong to the Chordopoxvirinae subfamily of the Poxviridae family. APVs are distributed worldwide and cause disease in domestic, pets and wild birds of many species. APVs infection not only makes the farming industry suffer huge economic losses, but also bring a great threat to wild fauna. In this study, through the analysis of clinical symptoms, virus isolation and purification, physicochemical properties, animal experiments and molecular biology methods on the naturally infected wild turtle dove, we proved that the pathogen of this disease is APV,which belongs to the Chordopoxvirinae subfamily of the Poxviridae family.Clinical symptoms and pathological changes of the natural infection turtle dove were observed in this study, the results showed body weigh losing, feathers messy, less hairy parts of their skin, including legs, chest and eyelids, appeared tan poxes of different size. Grossly necropsy showed no obvious lesions, while the results of histopathologic examination on the poxes from the leg showed that type A cytoplasmic inclusion bodies appeared in the plasma of epithelial cell and the cells had vacuolar degeneration. The TEM observation showed that there were many mature viral particles around the membrane structure in the plasma with the increased Golgi.A strain of virus was isolated through infecting CAM. The ELD50was10-370/0.2mL. This strain could also infect CEF, and the TCID50was10-4.8/0.05mL.Pathogenicity, physicochemical properties and pathogenicity studies of the virus showed that virus particles measure250×300nm with envelope and the shape of the virus was bric or oval. This strain could not resistive with heat, Whatmore, it would lose infection in the pH3.0and pH11.0, however, this stain was not sensitive to ethylether. The virus could not hold activity after exposuring under the UV radiation for60min. The virus can agglutinate chicken red blood cells.Though PCR of P4b core protein gene, a order of580bp sequences was obtained. Genetic analysis on this sequence order showed homology between the strain and the APV isolated from Columba palumbus was about99%. Analysising the evolution of P4b core protein gene of APV, this strain was so close to the A2but not belonged to A2.Through animal experiments on SPF chickens, we found that the chickens were lowly sensitive to SoPV and the infected chickens had short duration and light pathological damage. All the infected chickens returned to nomal after inoculation9d.It was certificated by all above that the pathogen causing this poxes disease was avainpoxvirus.