[Genetic characterization and correlation among fragments of HN gene of the field Newcastle disease viruses].

Twenty-four isolates of Newcastle disease virus (NDV) prevailing during 1997 -- 2005 in China were collected. These isolates were purified by CEF plaque assay and replicated in SPF chicken embryos. The hemagglutinin-neuraminidase (HN) genes of these viruses were cloned and sequenced. The HN gene sequences of thirty-six NDV reference strains in GenBank were also used in this study. The amino acid homologing of these viruses were compared and analyzed. The correlations among different fragments of HN gene were also analyzed. The results indicated that the homology of Chinese field NDV strains was 94.4%-99.4%, but 86.9%-89% compared with LaSota and Clone30, 87.9%-89.9% to F48E9, and 87.2%-96.2% to foreign NDV strains. There had the nearest distances among Chinese NDV isolates as compared with that of the LaSota, Clone30 and F48E9 by the phylogenetic tree. However, the distances of seven foreign NDV isolates were very close to Chinese NDV isolates as compared with these of the other foreign NDV isolates. We also found that all the Chinese field isolates were devoid of glycosylation site in position 538 -- 540. There were good correlations between different length amino acid fragments and the genomes of HN, especially the 5'-terminus first 80aa.

[Newcastle disease virus heredity mutation and correlation of HN and F gene].

Prevailed Newcastle disease virus isolates were collected during 1999-2005 in China. These isolates were purified by CEF plaque assay and replicated in SPF embryos. The fusion protein (F) gene and hemagglutinin-neuraminidase (HN) gene of these isolated viruses were cloned and sequenced. Some of the F gene and HN gene sequences from GenBank were also used in this study. The homologies of nucleotide and amino acids were compared and correlations were analyzed by SPSS8.0 software among different length sequences of the F gene or HN gene. The nucleotide homologies and correlation among the F gene and HN gene were also analyzed. The results indicated there are good correlation among different length sequences of the F gene or HN gene and the F genome or HN genome (r > or = 0.973). There was also good correlations among different length amino acids of NDV F protein or HN protein (0.911< or = r < or = 0.968). But, there was only a less correlation between the whole F gene and HN gene (r = 0.312). The heredity mutation of HN genes had the character of geographical areas. The sequences of HN gene in Chinese isolates had an identity of more than 97%. But there was only 79.2% - 80.7% in HN nucleotide homology among the Chinese isolates and La Sota (vaccine).