Newcastle disease virus (NDV) is classified as a member of the newly defined genus Avulavirus in the family of Paramyxoviridae. It is the causative agent of Newcastle disease (ND), which is widely distributed and has inflicted substantial economic costs to poultry industry worldwide. Aquatic birds are usually considered to be resistant even to most virulent NDV strains for chickens, however, outbreaks of clinical ND in goose flocks in Southern and Eastern China have been reported frequently since late 1990....