2株广西鹅源基因XII型新城疫病毒的病原学分析

【目的】深入了解2株广西鹅源基因XII型新城疫病毒(NDV)的病原学特征，为NDV流行分布的系统监测和新城疫(ND)的科学防控提供参考依据。【方法】对2株广西鹅源基因XII型NDV(Goose/China/GX02/2018和Goose/China/GX17/2018)进行病毒噬斑纯化，通过致死鸡胚平均死亡时间(MDT)和脑内接种致病指数(ICPI)试验确定其致病性，分析F蛋白和HN蛋白氨基酸序列与参考毒株的差异位点，并基于F基因全长进行遗传进化分析。【结果】经过DF-1细胞4个代次噬斑纯化可获得2株分离株的纯化株，对应的MDT分别为54和48 h,ICPI均为1.65。2株分离株的基因组长度均为15192 nt，其3’端引导序列为55 nt,5’端尾随序列为114 nt；基于F基因核苷酸序列相似性构建的基因XII型NDV系统发育进化树显示，2株分离株(Goose/China/GX02/2018和Goose/China/GX17/2018)均属于基因XIIb亚型，与我国广东分离株属于同一基因亚型，且我国2010年的分离株、2011年的分离株及2017年后的分离株分别形成3个小分支。2株...

Etiological analysis of 2 strains of genotype XII Newcastle disease viruses originated from geese in Guangxi

【Objective】To understand etiological characteristics of 2 strains of genotype XII Newcastle disease virus (NDV) originated from geese in Guangxi, so as to provide reference for systematic monitoring of NDV distribution and scientific prevention and control of ND.【Method】Two strains of genotype XII NDV(Goose/China/GX02/2018 and Goose/China/GX17/2018) from geese in Guangxi were purified by viral plaques. The pathogenicity of NDV was determined by mean time to death(MDT) of lethal chicken embryos and intracorporeal inoculation index(ICPI) test. The amino acid difference sites of F and HN proteins and reference strains were analyzed, and genetic evolution analysis was performed based on the full length of F gene.【Result】After 4 passages of plaque purification of DF-1 cells, two purified strains were obtained, corresponding to MDT of 54 h and 48 h, ICPI of 1.65 and 1.65, respectively. The genome length of the 2 isolates was 15192 nt, the 3'-end guide sequence was 55 nt, and the 5'-end trailing sequence was 114 nt. The phylogenetic tree of NDV genotype XII constructed based on the full length of F gene showed that the 2 isolates(Goose/China/GX02/2018 and Goose/China/GX17/2018) belonged to the XIIb subtype, the same subtype as the Guangdong strains. In addition, Chinese isolates in 2010, 2011 and 2017 formed 3 small branches respectively. The F protein cleavage site of the 2 isolates was 112RRQKRF117. Compared with the South American isolates(XIIa subtype) and the Vietnamese isolates(XIId subtype), there were 14 different amino acid sites in the signal peptide region, fusion peptide region, hepta-peptide repeat region and transmembrane region. Two amino acid differential sites(19I→V and 294N→S) were unique Guangxi isolates. The amino acid sequences of the transmembrane region and antigenic neutralization region of the HN protein of the 2 isolates were consistent with those of the Guangdong isolates, and there were seven amino acid differences(27V→I, 28A→S, 34V→I, 41A→T, 42V→A, 263K→R and 347E→D) compared with the South American isolates(subtype XIIa).【Conclusion】The amino acid differences in F protein and HN protein between Chinese isolates(subtype XIIb) and South American isolates(subtype XIIa) and Vietnamese isolates(subtype XIId) may be related to the differences in pathogenicity to chickens. In addition, NDV genotype XII is under constant evolution, and the epidemic distribution of NDV genotype XII needs to be continuously monitored.