Submitted to: Midwest Poultry Federation Proceedings
Publication Type: Proceedings
Publication Acceptance Date: March 4, 2013
Publication Date: March 12, 2013
Citation: Miller, P.J. 2013. The evolution of newcastle disease virus of low virulence. Midwest Poultry Federation Proceedings. p. 11. Interpretive Summary: Avian paramxyovirus of serotype-1(APMV-1) are also called Newcastle disease virus (NDV). If NDV have certain amino acids in their genome they are defined as virulent. If a virulent NDV infects poultry species this is defined as Newcastle disease and has to be reported to the authorities. In 2008 and 2009 NDV from turkeys were isolated that have a genome that is close to being virulent. These viruses grow well in turkeys but not as well in chickens. Their genomes are very similar to other wild bird NDV that we have in the United States. If one nucleotide changes in the genome of these MN turkey NDV and another basic amino acid is added, these viruses would be defined as virulent and have to be reported.
Technical Abstract: Newcastle disease viruses (NDVs) are also known as avian paramyxoviruses of serotype-1 (APMV-1). All NDVs (or APMV-1) are in one serotype and, by definition, antibodies produced from an exposure to any NDV will neutralize any other NDV. However, not all NDV (or APMV-1) cause Newcastle disease (ND). Only an infection with a NDV (or APMV-1) that is defined as virulent causes ND. Newcastle disease (ND) is defined as an infection of birds caused by an APMV-1 (NDV) that meets one of the following criteria for virulence: 1. The virus has an intracerebral pathogenicity index (ICPI) in day-old chicks (Gallus gallus) of 0.7 or greater; or 2. Three or more multiple basic amino acids have been demonstrated in the virus (either directly or by deduction) at residues 113-116 and phenylalanine at residue 117. Genotype X NDVs are of low virulence and had been isolated only in waterfowl from as early as 1987 (northern pintail/US (OH)/87-486/1987) with continued isolations (mottled duck/US (TX)/TX01-130/2001, blue winged teal/US (OH)/01-462/2001, mallard/US (OH)/04-411/2004) in different states. These viruses have typical fusion cleavage sites of low virulence NDV, 113G-K-Q-G-R-L117. Some NDVs isolated from MN turkeys showing mild respiratory disease in 2008 and 2009 are also contained in genotype X and are 97 to 98% similar to these wild bird NDVs, while they are only about 86% similar to the genotype II, LaSota or B1, vaccine strains. Characterization assays on the isolated MN NDVs found a non-virulent ICPI value (less than 0.7) in day old chickens and an unusual fusion cleavage site, 113K-Q-G-R-F117. The only other known NDVs reported with two basic amino acids with an F at position 117 have been from, 1] unidentified poultry species/US (FL)/live bird market/606/2007 (genotype I) and 2] goose/Italy/2010 (genotype II). For the glycine (G) in position 115 with the nucleotides GGG to change to the basic amino acid R (arginine) the first guanine of the GGG triplet would have to mutate to either a cytosine (C) or adenine (A). If this change occurs, this virus would, by definition, be a vNDV. Other assays performed suggest this NDV is adapted to growing in turkeys.