Submitted to: Virus Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/5/2001
Publication Date: 3/1/2002
Citation: Interpretive Summary: Several proteins made by Newcastle disease virus (NDV) are important for the virus to replicate. One of these is the nucleocapsid (N) protein. Much of the anterior portion of the protein has few amino acid changes. However, the posterior portion of the N protein of NDV has a far greater number of amino acid changes. This is very much like N proteins of similar viruses. There were several amino acids identified in the N protein of NDV that wer the same among related viruses. This indicates that these parts of the protein are probably very important for viral replication. Comparing the N protein genetic relationships among NDV isolates demonstrated again that there are two groups of viruses circulating worldwide. The NDV isolates causing disease are a genetically diverse set of viruses that are found worldwide.
Technical Abstract: The nucleocapsid (N) protein genes from twenty-four Newcastle disease virus (NDV) isolates representing various pathotypes with different geographical and chronological origins were cloned and sequenced. The N-terminal region of the N protein to residue 401 was highly conserved among isolates with several conservative substitutions occurring that correlated with phylogenetic relationships. Variability of the N protein was detected in the C-terminal portion similar to what has been reported for other members of the Paramyxovirinae. Amino acids previously identified as invariant or highly conserved in N proteins of other paramyxoviruses were also present in the NDV protein. Phylogenetic analysis of N gene coding sequences among NDV isolates again demonstrated existence of two major groups. One clade contained viruses that included vaccine and virulent strains isolated in the U.S. prior to 1970 while a second clade included vaccine and virulent viruses isolated worldwide. Comparison of N protein amino acid sequences among members of the Paramyxoviridae resulted in NDV and avian paramyxovirus 6 separating as a cluster distinct from the Rubulavirus genus. This provides further support for avian paramyxoviruses having their own genus among the Paramyxovirinae.