Molecular characterization of a virulent strain of Newcastle disease virus isolated from a diseased chicken in Kyrgyzstan in 2016

Newcastle disease (ND) is a contagious viral disease affecting birds throughout the world and causing economic losses in the poultry industry. At present, little is known about the genetic causes of the ND outbreak that occurred in commercial poultry farms in Kyrgyzstan in 2016. In the current study, we isolated and confirmed a strain of ND virus (NDV) isolated from one out of two samples obtained from an unvaccinated flock. Based on phylogenetic analyses, this NDV strain was clustered in the class II subgenotype VIId and was closely related to the Chinese NDV isolate. Phylogenetic analyses also revealed that the isolated NDV strain has an origin different from the four NDV strains previously identified in Kyrgyzstan. According to a multibasic amino acid (aa) sequence at the F0 proteolytic cleavage site (R-112-R-Q-K-R-F-117), the NDV isolate was determined as a virulent strain. Several mutations in the neutralizing epitopes (notably, E-347 -> K) and the global head were observed in the hemagglutininn-euraminidase protein of the new isolate. The present study represents the first molecular characterization of the coding region of NDV genome obtained from Kyrgyzstan in 2016. This essential information may be useful for ND diagnostics and control.