Identification of an additional N-glycosylation site and Thermostable mutations within the Hemagglutinin-Neuraminidase gene of the Newcastle disease virus belonging to the VII.1.1 subgenotype.

Abstract

Newcastle disease virus (NDV) is considered one of the most devastating avian viral pathogenic agents, causing a tremendous economic burden to the poultry industry worldwide. The current study was conducted to gain deep insights into the molecular and phylogenetic analyses of the complete hemagglutinin-neuraminidase (HN) coding region among NDV isolates. The collected samples, obtained from different parts of Iran from July 2017 to February 2020, were used for phylogenic analysis during this study. The results confirmed the VII.1.1, which was previously known as subgenotype VIIL, as the predominant subgenotype circulating in commercial broiler farms of Iran. Identification of (a) an additional N-glycosylation site at position 144 (NIS); (b) mutations S315P and I369V related to increasing the viral thermostability; (C) cysteine residues at positions 123; (d) amino acid substitutions in the HN antigenic sites, especially the mutations I514V and E347Q, as well as the other mutant within HN binding sites of the VII.1.1 subgenotype, seems to suggest the idea that this new subgenotype of NDV may possess a high level of pathogenicity and virulence among other NDV subgenotypes. Furthermore, the annual rate of change based on the HN gene of Iranian NDV was calculated at about 1.8088E-3 from 2011 to 2020. In conclusion, the results demonstrate an additional N-glycosylation site at position 144 (NIS), which may alter the virulence of the isolates. Besides, finding the thermostable mutations (S315P and I369V) and the other amino acid substitutions among the VII.1.1 subgenotype isolates may lead to vaccination failure against this new NDV subgenotype.