Qiu Xusheng, Sun Qing, Yao Chunfeng, Dong Li, Wu Yantao, Hu Shunling, Liu Xiufan
Key Laboratory of Animal Infectious Diseases, Yangzhou University, Yangzhou 225009, China.
Wei Sheng Wu Xue Bao. 2009 Mar;49(3):302-8.
The purpose of this research is trying to uncover the homology between two velogenic genotype III Newcastle disease virus (NDV) isolates with NDV strain Mukteswar, which was commonly used as vaccine in China.
The full-length genome of NDV isolates, JS/7/05/Ch and JS/9/05/Go, were determined by RT-PCR and then analyzed.
The full-length genome of 2 genotype III velogenic NDV isolates shared 99.7% nucleotide identity with that of Mukteswar. The results of alignment of 6 viral genes showed that JS/7/05/Ch and JS/9/05/Go shared nucleotide and amino acid identities of 99.6% - 99.9% and 98.8% - 99.8% with that of Mukteswar, respectively. Furthermore, the IVPI score of JS/7/ 05/Ch and JS/9/05/Go was 2.18 and 1.33, remarkablely higher than that of Mukteswar, while the 3 NDV strains shared the consensus cleavage site of virulent NDV strains (112RRQRRF117). Virulence of NDV is mainly determined by the amino acid sequence of the fusion (F) protein cleavage site, since host proteases that cleave the F protein of virulent strains are present in more tissues than those that cleave the F protein of lentogenic strains. However, 3 NDV strains with same F protein cleavage site showed different virulence. The entire genomic sequence of JS/7/05/Ch, JS/9/05/Go and Mukteswar was further analyzed. Three strains shared some gene-start signal, gene-end signal, intergenic region and six highly identical viral genes. Most amino acid differences among JS/7/05/Ch, JS/9/05/Go and Mukteswar were found in the predicted HN and L protein, and the predicted NP, P, V, W, M and even F protein had few amino acid differences.
First, it is concluded that field isolates JS/7/05/ Ch and JS/9/05/Go are derived from Mukteswar and more attention must be paid to the virulence enhancement of vaccine strains. Second, it is proposed that the differences in the amino acid sequence of HN and L protein may give rise to the significant virulence differences between two NDV isolates and Mukteswar.
本研究旨在揭示两株速发型基因型III新城疫病毒（NDV）分离株与中国常用疫苗株Mukteswar之间的同源性。
通过RT-PCR测定NDV分离株JS/7/05/Ch和JS/9/05/Go的全长基因组，随后进行分析。
两株基因型III速发型NDV分离株的全长基因组与Mukteswar的核苷酸同一性为99.7%。6个病毒基因的比对结果显示，JS/7/05/Ch和JS/9/05/Go与Mukteswar的核苷酸同一性和氨基酸同一性分别为99.6% - 99.9%和98.8% - 99.8%。此外，JS/7/05/Ch和JS/9/05/Go的静脉内致病指数（IVPI）得分分别为2.18和1.33，显著高于Mukteswar，而这三株NDV毒株具有强毒株NDV的共有裂解位点（112RRQRRF117）。NDV的毒力主要由融合（F）蛋白裂解位点的氨基酸序列决定，因为裂解强毒株F蛋白的宿主蛋白酶比裂解弱毒株F蛋白的宿主蛋白酶存在于更多组织中。然而，具有相同F蛋白裂解位点的三株NDV毒株表现出不同的毒力。对JS/7/05/Ch、JS/9/05/Go和Mukteswar的全基因组序列进行了进一步分析。三株毒株共享一些基因起始信号、基因终止信号、基因间隔区和六个高度同源的病毒基因。JS/7/05/Ch、JS/9/05/Go和Mukteswar之间的大多数氨基酸差异存在于预测的血凝素神经氨酸酶（HN）和大（L）蛋白中，而预测的核衣壳蛋白（NP）、磷蛋白（P）、V蛋白、W蛋白、基质蛋白（M）甚至F蛋白的氨基酸差异很少。
首先，得出结论，田间分离株JS/7/05/Ch和JS/9/05/Go源自Mukteswar，必须更加关注疫苗株的毒力增强问题。其次，提出HN和L蛋白氨基酸序列的差异可能导致两株NDV分离株与Mukteswar之间存在显著的毒力差异。
