Selim Karim M, Selim Abdullah, Arafa Abdelsatar, Hussein Hussein A, Elsanousi Ahmed A
National Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, P.O. Box 264-Dokki, Giza 12618, Egypt.
Department of Virology, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt.
Vet World. 2018 Jul;11(7):930-938. doi: 10.14202/vetworld.2018.930-938. Epub 2018 Jul 15.
The aim of this work was to study the full F gene sequence of Newcastle disease virus (NDV) in regard to pathotyping and genotyping and to study the evolution of this NDV in Egypt.
The present study was conducted using samples from seven suspected NDV flocks of vaccinated chickens during 2012-2016 from six governorates in Egypt. The NDV was successfully isolated from pathological specimens through inoculation in specific pathogen-free embryonated chicken eggs.
Pathogenicity of the NDV isolates has been estimated through intracerebral pathogenicity index and ranged from 1.66 to 1.73 which indicates the velogenic type of NDV isolates. Pathotyping and genotyping of these isolates were done through sequencing of full-length F gene. Results indicated that the seven NDV isolates showed characteristic cleavage site motif (112RRQKRF117) for the velogenic strains of NDV. Phylogenetic analysis of the F gene clustered these isolates within Group I of genotype VIId within Israeli strains NDV/IS/2015, NDV-Ch/SD883, and most of the Middle East strains. Six of seven sequenced isolates have six potential N-linked glycosylation sites. The neutralization epitope on the five antigenic sites of fusion is conserved in all Egyptian strains of this study except NDV-KFR-B7-2012 which has a substitution at D 170 N in epitope A4. In all our strains, 10 cysteine residues are recorded, except one loss of cysteine at residue 370 in both NDV-EG-35-2014 and NDV-GHB-328F-2016.
All viruses in this study have 52 amino acid substitutions within fusion gene in compared with Lasota strain that reveals importance for its antigenic and structural function. The present work highlights the important need to sequence F gene of NDV genotype VIId to investigate the evolution of this NDV in Egypt.
本研究旨在对新城疫病毒（NDV）的完整F基因序列进行致病型和基因分型研究，并探究该病毒在埃及的进化情况。
本研究采用2012年至2016年期间从埃及六个省份的七个疑似感染NDV的疫苗接种鸡群中采集的样本。通过接种于无特定病原体的鸡胚，成功从病理标本中分离出NDV。
通过脑内致病指数评估了NDV分离株的致病性，范围为1.66至1.73，表明这些分离株为强毒株。通过对全长F基因进行测序，对这些分离株进行了致病型和基因分型。结果表明，这七个NDV分离株显示出NDV强毒株的特征性裂解位点基序（112RRQKRF117）。F基因的系统发育分析将这些分离株聚类在基因型VIId的第一组内，与以色列毒株NDV/IS/2015、NDV-Ch/SD883以及大多数中东毒株聚在一起。七个测序分离株中有六个具有六个潜在的N-连接糖基化位点。除了NDV-KFR-B7-2012在表位A4的D170N处有一个替换外，本研究中所有埃及毒株融合蛋白五个抗原位点上的中和表位均保守。在我们所有的毒株中，记录到10个半胱氨酸残基，除了NDV-EG-35-2014和NDV-GHB-328F-2016在残基370处均缺失一个半胱氨酸。
与LaSota毒株相比，本研究中的所有病毒在融合基因内有52个氨基酸替换，这揭示了其在抗原和结构功能方面的重要性。本研究强调了对NDV基因型VIId的F基因进行测序以研究该病毒在埃及进化情况的重要需求。
