Molecular and biological characterization of some circulating strains of Newcastle disease virus in broiler chickens from Eastern Saudi Arabia in 2012-2014.

Abdullah I A Almubarak

doi:10.14202/vetworld.2019.1668-1676

Abstract

Background and Aim:Newcastle disease (ND) is a worldwide poultry disease that is historically known to cause severe losses in the poultry industry. In the present study, attempts were made to characterize ND virus (NDV) recovered from broiler chickens in the Eastern Region of Saudi Arabia from January 2012 to March 2014.Materials and Methods:Reverse transcription-polymerase chain reaction was used for the detection of NDV followed by partial sequencing of the fusion (F) gene. The intracerebral pathogenicity index (ICPI), mean death time (MDT), and complete sequencing of the hemagglutinin-neuraminidase (HN) gene were also used for further biological and molecular characterization.Results:NDV was detected at a rate of 9.6% (11/115) of the tested flocks, most of which were vaccinated against ND. F gene-based phylogeny and motifs of the fusion protein cleavage site (FPCS) showed segregation of Saudi isolates into two groups. The first group contained 10 isolates and was located in genotype II with the lentogenic motif 112GRQGRL117 at the FPCS. The second group contained one isolate and was located in genotype VII with velogenic motif 112RRQKRF117. Further characterization using the ICPI and MDT of two representative isolates showed virulence of both tested isolates. Phylogenetic analysis of the HN gene showed close nucleotide identity between the two isolates. A BLAST search for sequences similar to HN gene sequences showed high identity with isolates from the surrounding region.Conclusion:The present findings showed a low detection rate of NDV, possibly due to the wide application of vaccines, and the circulation of at least two NDV genotypes, II and VII, in the Eastern Region of Saudi Arabia. The present Saudi isolates may share common ancestors with isolates from the surrounding region.

Highlights

Newcastle disease (ND) is one of the most important poultry diseases in terms of the number of birds lost [1]
ND virus (NDV) was detected at a rate of 9.6% (11/115) of the tested flocks, most of which were vaccinated against ND
Samples were tested for the presence of NDV using reverse transcription-polymerase chain reaction (RT-PCR)

Summary

Introduction

Newcastle disease (ND) is one of the most important poultry diseases in terms of the number of birds lost [1]. The causative agent, ND virus (NDV), is an avian paramyxovirus type I (APMV-1) belonging to the genus Avulavirus and family Paramyxoviridae [2]. It has the ability to infect a wide range of avian species, and 240 bird species were reported to be susceptible [3,4]. Wild and domesticated birds were implicated as a reservoir of NDV and a possible mode of dissemination [5,6]. Newcastle disease (ND) is a worldwide poultry disease that is historically known to cause severe losses in the poultry industry. Attempts were made to characterize ND virus (NDV) recovered from broiler chickens in the Eastern Region of Saudi Arabia from January 2012 to March 2014

Methods

Results

Conclusion