Qin Zhuo-ming, Ma Bao-chen, Jia Qiang, Ouyang Wen-jun, Cui Zhi-zhong, Xu Huai-ying, Yuan Xiao-yuan
College of Animal Science and Technology, Shandong Agriculture University, Tai'an 271018, China.
Wei Sheng Wu Xue Bao. 2006 Dec;46(6):912-6.
Newcastle disease virus (NDV) field strain SQZ04 was isolated from a broiler flock with typical symptoms and lesions, and cloned by plaque-purification three times. NDV SQZ04 was determined as a virulent strain with MDT of 50.5h and 51.2h, ICPI of 2.0 and 1.92, IVPI of 2.8 and 2.68 respectively before and after plaque-purification. Analysis of F gene indicated that SQZO4 was determined as a virulent gene type II , and its protein amino acid sequence has homologies of 99.3% , 98.7% and 96.9% with published gene type II vaccine strains LaSota, B1, virulent strain Taxas48,much higher than homologies of 88.3% - 88.6% or 91.3% - 92.1% with published gene types VI and IX. This is the first virulent field strain of gene type UI reported in China. Further more, the amino acid sequence 111 GGRQGRL117 in the F protein cleavage site in SQZ04 strain is identical to lentogenic strains of NDV, such as vaccine strains LaSota, B1. This is the first report that virulent NDV could have lentogenic amino acid sequence in the cleavage site of F protein, where HN genes was compared SQZ04 has a higher homologies of 95.3%- 97.3% with known velogenic strains, but lower homologies of 87.8% - 89.5% with published lentogenic strains.
新城疫病毒（NDV）野毒株SQZ04从出现典型症状和病变的肉鸡群中分离得到，并通过空斑纯化法克隆了3次。NDV SQZ04被确定为强毒株，空斑纯化前后的平均死亡时间（MDT）分别为50.5小时和51.2小时，脑内接种致病指数（ICPI）分别为2.0和1.92，静脉接种致病指数（IVPI）分别为2.8和2.68。F基因分析表明，SQZO4被确定为强毒基因Ⅱ型，其蛋白氨基酸序列与已发表的基因Ⅱ型疫苗株LaSota、B1、强毒株Texas48的同源性分别为99.3%、98.7%和96.9%，远高于与已发表的基因Ⅵ型和Ⅸ型88.3% - 88.6%或91.3% - 92.1%的同源性。这是中国首次报道的基因Ⅱ型强毒野毒株。此外，SQZ04株F蛋白裂解位点的氨基酸序列111 GGRQGRL117与NDV的弱毒株如疫苗株LaSota、B1相同。这是首次报道强毒NDV在F蛋白裂解位点可能具有弱毒氨基酸序列，其中HN基因与已知强毒株的同源性为95.3% - 97.3%，但与已发表的弱毒株的同源性较低，为87.8% - 89.5%。
