Pathogenicity of Genotype VII virulent Newcastle Disease Virus for Cherry Vally Ducks

Twenty Cherry Vally ducks and SPF chickens were challenged with genotype Ⅶ virulent Newcastle disease virus (NDV) at a dose of 108 ELD50. In addition,ten ducks and SPF chickens were not infected by NDV and used as controls. Splanchnic tissues (liver,spleen and lung),cloacal and tracheal swabs of ducks were collected after 1,4,7 and 14 days post-challenge for virus isolation. At the same time,ducks were bled and their sera were tested for ND antibodies by haemagglutination inhibition test. Chickens of both groups were dead at day 5 to 9 post infection. Ducks from both groups,challenged or not,didn′t show any ND clinical signs with in 14 days. NDV was isolated from ducks 7 to 14 days after challenge. Ducks were tested positive for ND antibodies 14 days post infection. This study had shown that although ducks could be infected with virulent NDV,they had no clinical signs. NDV could replicate in ducks and was shed though throat and cloaca,which was important for the epidemiology of ND.