Whole genome sequencing and phylogenetic relative of a pure virulent Newcastle disease virus isolated from an outbreak in northeast Iran.

Abstract

Newcastle disease (ND) is a significant viral disease affecting poultry worldwide, with outbreaks persisting despite extensive vaccination efforts. This study characterizes a novel NDV strain, RT40, isolated from poultry farms in northeast Iran for the first time. RT40, classified as genotype VII, subgenotype VII.1.1, has a genome length of 15 192 nucleotides, with six genes, 12 UTRs, and five IGS, consistent with class II NDVs. Pathogenicity tests confirm its virulent velogenic nature, differentiating it from other known strains. Phylogenetic analysis points to a Western origin, suggesting possible cross-border transmission with Iraqi strains, highlighting the strain's relevance for NDV surveillance. Virus isolation, RNA sequencing, and cross-border transmission analysis were performed, revealing that RT40 shares a high nucleotide sequence identity with Iraqi strains, further supporting cross-border transmission concerns. The findings underscore the need for genotype-specific vaccines tailored to circulating strains. The genome, deposited in GenBank (accession ON184061), serves as an essential resource for future research and vaccine development. By emphasizing whole-genome sequencing, this study aims to improve NDV evolution tracking and enhance understanding of NDV diversity. This work calls for targeted vaccine strategies to effectively manage NDV spread, ensuring the sustainability of the poultry industry.