Genetic characterization and evolutionary analysis of Newcastle disease virus isolated from domestic duck in South Korea

• We present the complete genome sequence of NDV strain DK13 isolated in South Korea in the year 2007.
• We investigated the phylogenetic relationships of this virus with reference NDV strains.
• Categorized and classified DK13 strain as a lentogenic and a member of class II, genotype I.
• We determined its ancestral state location and year of TMRCA with sister strain.
• Understanding the evolutionary process of strains belonging to genotype I.

Domestic ducks are considered a potential reservoir of Newcastle disease virus. In the study, a Newcastle disease virus (NDV) isolated from a domestic duck during surveillance in South Korea was characterized. The complete genome of the NDV isolate was sequenced, and the phylogenetic relationship to reference strains was studied. Phylogenetic analysis revealed that the strain clustered in genotype I of Class II ND viruses, has highly phylogenetic similarity to NDV strains isolated from waterfowl in China, but was distant from the viruses isolated in chickens and vaccine strains used in South Korea. Pathogenicity experiment in chickens revealed it to be a lentogenic virus. The deduced amino acid sequence of the cleavage site of the fusion (F) protein confirmed that the isolate contained the avirulent motif 112GKQGRL117 at the cleavage site and caused no apparent disease in chickens and ducks. With phylogeographic analysis based on fusion gene, we estimate the origin of an ancestral virus of the isolate and its sister strain located in China around 1998. It highlights the need of continuous surveillance to enhance current understanding of the molecular epidemiology and evolution of the pathogenic strains.