Identification and molecular characterization of a novel flavivirus isolated from geese in China.

Since April 2010, a novel contagious disease in ducks and geese, with egg drop, feed uptake decline and neurological signs, caused by a newly emerged virus has spread around Eastern China. Dissection conducted on the dead geese demonstrated hemorrhage in brain, lung, liver, heart, ovary, and enlarged and necrotic spleen. A new virus, named Goose/Jiangsu/804/2010 (JS804) virus, was isolated in Jiangsu area from geese. Then the virus was re-isolated from the affected geese and replicated well in duck embryo fibroblasts and Vero cells, causing the cytopathic effect. The virus was identified as an enveloped positive stranded RNA virus with a size of approximately 40-60 nm in diameter. The full-length genome of this isolated virus was determined, showing that it is closely related to Tembusu virus (a mosquito-borne Ntaya group flavivirus) than other members of the Flaviviridae based on the data of phylogenetic analyses. Our systematic studies fulfill Koch's postulates precisely, and therefore, the causative agent of geese occurring in Eastern China is a new flavivirus. This is the first report that flavivirus infects not only egg-laying and breeder ducks but also geese. The findings extend our understanding of how the virus spreads and causes disease.