Isolation and Molecular Characterization of Newcastle Disease Virus Genotype VII Circulating in Egypt (2017-2020)

Ragab, Elham S. M.; Moharam, Ibrahim; El-Naggar, Rania F.; Hussien, Eid G. S.; El-Kanawati, Zakaria R.; AboElkhair, Mohammed A.

doi:10.21608/jcvr.2022.267507

Isolation and Molecular Characterization of Newcastle Disease Virus Genotype VII Circulating in Egypt (2017-2020)

Document Type : Original Article

Authors

¹ Reference Laboratory for veterinary quality control on poultry production, Animal Health Research Institute, Agriculture Researches, Center, Egypt.

² Department of Bird and Rabbit Medicine, Faculty of Veterinary Medicine, University of Sadat City, Minoufiya, Egypt.

³ Department of Virology, Faculty of Veterinary Medicine, University of Sadat City, Minoufiya, Egypt.

10.21608/jcvr.2022.267507

Abstract

Despite the frequent use of ND vaccines in Egypt, Newcastle Disease Virus still causes outbreaks in the commercial, backyard, and wild captive poultry. Avian Orthoavula virus 1 (AOaV-1) belongs to the genus Orthoavulavirus and causes ND in a variety of avian species around the world. To explore the evolution of the NDV and evaluate the efficacy of the vaccine regimens currently being used in Egypt's commercial poultry, spleen, brain, ileocecal tonsil, and tracheal tissue specimens were collected from twenty-three vaccinated broiler flocks from four Egyptian governorates (Kafr-Elsheikh, Alexandria, Matrouh, and El-Behera) between 2017 and 2020 for molecular analysis. qRT-PCR was used to characterize the NDV that was propagated in specific pathogen-free embryonated chicken eggs (SPF ECEs). The isolates were screened for other endemic avian respiratory viruses including avian influenza and infectious bronchitis viruses. Five isolates were selected for further genetic characterization, based on the motif of the cleavage site (112RRQKR ↓F117) in the fusion (F) protein. All five isolates were identified as velogenic NDV strains based on partial-length F gene sequences. These isolates are clustered into subgenotype VII.1.1 of the class II of ND viruses, which is the main genotype in the Egyptian poultry industry and in those of many Middle East countries.

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