Isolation and characterization of a recent Newcastle disease virus from infected backyard chickens in Egypt

Genomic surveillance of Newcastle disease virus is critical for determining the genetic diversity of circulating strains and improving preparedness and response to potential outbreaks. Backyard poultry continue to present significant challenges to Newcastle disease virus control due to inadequate biosecurity, poor vaccination practices, and close interactions with migratory birds. This study was designed to isolate and characterize Newcastle disease virus from infected backyard chickens in Qalubia governorate, Egypt. The hemagglutination test and reverse transcription-polymerase chain reaction, targeting a partial segment of the F-gene, confirmed an isolate as Newcastle disease virus. Positive Newcastle disease virus isolate was sequenced and phylogenetically analyzed, revealing that it belongs to Newcastle disease virus genotype VII.1.1. It was deposited in the NCBI GenBank (CLEVB1/2024) under Accession Number PP130129. The data further confirmed that the CLEVB1 isolate had the cleavage site motif 112RRQKRF117, characteristic of velogenic Newcastle disease virus strains. Based on amino acid sequence comparison, the CLEVB1 isolate shared 99.2 % homology with strains teal/Egypt/SDU-3/2016 and quail/Egypt/SDU-2/2016, which were both isolated from migratory birds in 2016. Therefore, the CLEVB1 isolate is thought that it was originated from two previously identified Newcastle disease virus strains, highlighting the results of ongoing interactions between migratory birds and backyard poultry. It is recommended that continuous Newcastle disease virus surveillance and routine vaccination in backyard poultry sectors are mandatory to reduce the risk of future outbreaks.