Submitted to: Virus Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 7, 1999
Publication Date: January 1, 2000
Citation: SEAL, B.S., KING, D.J., MEINERSMANN, R.J. MOLECULAR EVOLUTION OF THE NEWCASTLE DISEASE VIRUS MATRIX PROTEIN GENE AND PHYLOGENETIC RELATIOHSHIPS AMONG THE PARAMYXOVIRIDAE. VIRUS RESEARCH. 2000. Interpretive Summary: Newcastle disease virus (NDV) is an economically important pathogen of commercial poultry that can also infect many species of wild birds. Genetic nucleotide sequence data was used to determine relationships among many different NDV isolates from chickens and free-living birds. Isolates recently obtained are very different from older isolates obtained from the U.S. that are commonly used for vaccination of commercial poultry. Also, these new NDV types have recently expanded so that there is now more difference in their genetic makeup. This indicates that these viruses are changing with time. Finally, the information obtained indicates that NDV should be separated as its own taxonomic group among similar viruses.
Technical Abstract: Matrix (M) gene sequences for several recent and older reference Newcastle disease virus (NDV) isolates were examined to determine phylogenetic relationships and population trends among these viruses. Overall the M gene appears to be undergoing purifying selection with a majority of synonymous nucleotide sequence substitutions occurring. Nucleotide substitutions in some codons have a greater number of nonsynonymous base changes and indicate that specific portions of the protein may be under selective pressures. The NDV isolates arising since the 1970's belong to a population of viruses that appear to be expanding at an exponential rate. These viruses may have their origins in free-living birds, are present worldwide, and continue to circulate causing disease in poultry. A specific NDV lineage composed of virulent isolates obtained in the U.S. prior to 1970 no longer exists among free-living birds or commercial poultry. However, "vaccine-like" viruses are common in the U.S. and continue to circulate among commercial poultry. Based on M protein amino acid sequences NDV separates as a clade most closely related to morbilliviruses and not with their current designated category, the rubulaviruses among the Paramyxoviridae. Consequently, avian paramyxoviruses should have their own taxonomic subfamily among the Paramyxovirinae.