Cloning and Sequence Analysis of F Gene of NDV Strain Isolated from Crested Ibis in Shaanxi Provence

F protein coded by F gene of Newcastle disease virus has close relationship with pathogenicity of the virus and immune response.The characteristics of molecular biology of crested ibis NDV isolated in Shaanxi province were researched to find out its variation and evolution.The main functional region of the F gene comprising 535 bp nucleotides was amplified by RT-PCR and sequenced.Phylogenetic analysis based on the F gene was carried out.The result showed that the amplifying sequence was accordant with the length of expecting fragment.The deduced amino acid sequence at the cleavage site of the F protein was112R-R-Q-K-R-F117,which is the same as virulent strains of NDV.The polyogenetic tree analysis showed that this strain belonged to the genotype Ⅶ,and was consistent with the NDV genotypes reported in China in recent years.