Newcastle disease virus Genotype VII in Chicken Flocks in Dakahlia Governorate and the Effectiveness of some Vaccines

Document Type : Original Article

Authors

1 Animal Health Research Institute

2 Avian and Rabbit Medicine Department, Faculty of Veterinary Medicine- Zagazig University

3 Poultry and Rabbit Diseases Department, Faculty of Veterinary Medicine, Mansura University

Abstract

Out of fifteen chicken flocks, ten were tested Newcastle Disease Virus (NDV) positive by RT-PCR. Two selected NDV isolates from previously vaccinated flocks were selected for further investigation. The isolates were proofed negative for the presence of either infectious bronchitis virus (IBV) or avian influenza virus (AIV) genome. The mean death time and intracerebral pathogenicity indices as well as the presence of 112RRQKRF117  motif at the F gene cleavage site were indicative for the virulence of the investigated strains. The phylogenetic analysis showed that the velogenic genotype isolate clustered with published class II genotype VII and closely related to Middle East isolates. In vivo protection assay revealed that vaccination with live and/or inactivated ND vaccines induced sufficient protection ranged between 86.7 % and 100 % against morbidity and mortality as judged by HI titers and challenge test with NDV genotype VII.

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