Isolation,Identification and Molecular Characterization of a Velogenic NDV Isolate from a Broiler Flock in High Antibody Level Against NDV

Abstract:

A Newcastle disease virus(NDV)field strain SGM01 was isolated from a broiler flock in high antibody level against NDV,and identified by HA,HI cross test and animal regression.SGM01 was determined as a virulent strain with MDT of 50.5h,ICPI of 1.76,IVPI of 2.41 after plaque-purification.The F and HN gene of SGM01 were cloned and sequenced.Analysis of F gene indicated that SGMOI be- longed to genotypeⅦ.The amino acid sequence ¹¹¹GGRQGRL¹¹⁷ in the F protein cleavage site in SGM01 strain is identical to virulent NDV.The homology analysis of F and HN gene sequences compared to reference stains from GenBank indicated that:The F protein amino acid se-quence has homologies of 87.7%～88.3% with published gene type Ⅱ strains LaSota and SQZ04 et al.,95.7%～98.2% with genotype Ⅶ strains Taiwan95、Yunnan03 et al., 91.8%～91.7% with genotype Ⅸ strains F₄₈E₉et al., While HN genes were compared,SGM01 demonstrated a higher homologies of 96.5%～97.2% with strains which were isolated in recent years,but lower homologies of 87.4% and 89.0% with LaSota and F₄₈E₉.

Key words:Newcastle disease virus; High antibody level; Molecular characterization