A study of Newcastle disease virus obtained from exotic caged birds in Tehran between 2009 and 2010

Abstract

The aim of this study was to investigate the frequency of the Newcastle disease virus (NDV) infection and its virulence in exotic cage birds over a limited area and time period. A set of 335 samples was collected from 24 different species of exotic unvaccinated cage birds kept in the zoological gardens and bird markets of the Tehran province of Iran during 1.5 years. Except for three pigeons, all of the sampled birds were healthy with no clinical signs of Newcastle disease. NDV was detected in three sick pigeons by haemagglutination assay (HA), haemagglutination inhibition (HI) and reverse transcription-polymerase chain reaction (RT-PCR) tests while two of them were identified as virulent types by RT-PCR. Although the remaining samples were negative by Newcastle-disease-specific HA and HI tests, 35 of them (10%) were identified as positive and 25 (72%) were determined as the velogenic type by RT-PCR test. Five PCR products were sequenced and all were confirmed as NDV but sequences were different from each other and from other sequences from Iran. In total, 14 species (58%) were infected and 10 species were uninfected with the velogenic type without showing any signs. Pigeons are very sensitive to NDV infection and play an important role in its epidemiology. In this study, the PCR test was found to be a more sensitive and powerful method than the HA and HI tests for detection of NDV reservoirs and carrier status in exotic birds. Also, the frequency of infection with the virulent type showed that the exotic birds should probably be considered one of the main causes of recurrent annual epidemics of Newcastle disease in endemic regions.

Pathotypic characterization of Newcastle disease virus isolated from vaccinated chicken in West Java, Indonesia

“…The previous study has improved RT-PCR using pathotype specific primers to detect and differentiate virulence of NDV strains; this technique seems to be more efficient for NDV pathotyping [11,12]. The pathotype specific primers set was conducted based on nucleotides sequence at the F gene cleavage site, which has been shown to be a major determinant of NDV virulence [13-15]. …”

Isolation, Identification and Molecular Characterization of Highly Pathogenic Newcastle Disease Virus From Field Outbreaks

“…Infected samples indicated the presence of virus identified by chicken embryonated egg inoculation and haemagglutination assay [2]. NDV has a wide range of hosts range, inclusive of approximately 241 species [12] belongs to 27 orders out of which 50 orders of birds [13]. In various developing countries, ND is an endemic and thus have a high economic impact.…”

Molecular Detection of Lentogenic Strain of Newcastle Disease Virus in Commercial Broiler Chickens Using Sentinel Birds in Iran: The First Report

“…All recently characterized Iranian NDV isolates which detected from commercial farm, rural area and different species belong to Genotype VII and had virulent motif at F protein cleavage site [5,7,13,14]. The primary molecular determinant for NDV pathogenicity is the fusion protein cleavage site and the ease by which cellular proteases cleave the fusion protein.…”