Molecular Characterization of Virulent Newcastle Disease Virus Isolates from Chickens during the 1998 NDV Outbreak in Kazakhstan

Abstract

Newcastle disease virus (NDV) infects domesticated and wild birds throughout the world and has the possibility to cause outbreaks in chicken flocks in future. To assess the evolutionary characteristics of 10 NDV strains isolated from chickens in Kazakhstan during 1998 we investigated the phylogenetic relationships among these viruses and viruses described previously. For genotyping, fusion (F) gene phylogenetic analysis (nucleotide number 47-421) was performed using sequences of Kazakhstanian isolates as compared to sequences of selected NDV strains from GenBank. Phylogenetic analysis showed that all newly characterized strains belonged to the genetic group designated as VIIb. All strains possessed a virulent fusion cleavage site (RRQRR/F) belonging to velogenic or mesogenic pathotypes with intracerebral pathogenicity indexes (ICPI) varying from 1.05 to 1.87.

Pathotypical Characterization and Molecular Epidemiology of Newcastle Disease Virus Isolates from Different Hosts in China from 1996 to 2005

“…Clinical signs of the disease were similar among most poultry farms. Filtrates of processed tissues from the trachea, oviduct, brain, and spleen from different hosts were used to inoculate specific-pathogen-free (SPF) eggs (Institute of Shandong Poultry Science) as previously reported (9,16,20,25). All viruses were purified three times using the virus plaque technique before being propagated in SPF embryonated eggs.…”

Newcastle disease outbreaks in Kazakhstan and Kyrgyzstan during 1998, 2000, 2001, 2003, 2004, and 2005 were caused by viruses of the genotypes VIIb and VIId

“…The presence of isolates of genotype VIIb in southern Africa and their involvement in the NDV outbreaks of the 1990s was first described by Herczeg et al [10]. The occurrence of other isolates characterized as subtypes of genotype VII have also been reported: VIIa in the Far East and Europe [11,12]; VIIb in the Far East, Middle East, Europe [13][14][15][16], India, and southern Africa [17,18]; VIIc in the Far East and Europe; and VIId in the Far East and South Africa [6,18].…”

“…The strains were labeled with the codes of country and a serial number in order of receipt (Table 1). Allantoic fluids were harvested from ECE inoculated with the viruses and used as a stock for sequence analysis and other virus characterization tests [16].…”

“…If detection was positive, two sets of second round PCR were carried out with primers 614F/1082R and 1005F/1356R (temperatures/times: 94°C/25 s, 53°C/25 s, and 72°C/90 s for 35 cycles). Primers 1045F, 614F, 601R, 1082R, 480F, 1356R, and 1005 F used in this research were described earlier [16]. Primer 614F was used for transcription, and the other primers were used for sequencing.…”

“…In a previous study [16], 10 Kazakhstanian viruses isolated during 1998 were analyzed phylogenetically and found to be genotype VIIb. In this study, 28 additional NDV isolates obtained from outbreaks occurring between 1998 and 2005 in Kazakhstan and Kyrgyzstan are characterized molecularly, and the epidemiology of ND is evaluated on the basis of molecular analysis of the F protein gene of those isolates.…”