一株新城疫病毒野鸟分离株的生物学特性研究

Biological characteristics of a Newcastle disease virus isolated from wild birds

野鸟是新城疫病毒(NDV)重要的自然宿主,在NDV的传播和进化中起着重要作用。Mallard/CH/HLJ127/06是2006年分离自黑龙江省野鸟的一株NDV。本研究对其进行了全基因组序列测定、遗传进化分析、抗原相关性分析;并测定了病毒株毒力指标及致病性特点。结果显示Mallard/CH/HLJ127/06属于class II中的基因VII型病毒株。F蛋白裂解位点为^(112)RRQKRF^(117)。抗原相关性分析表明Mallard/CH/HLJ127/06与基因VII型代表性病毒株之间没有显著的抗原性差异。致病指数MDT (最小致死剂量病毒致死鸡胚的平均时间)值为68 h,ICPI (脑内接种致病指数)值为1.975。致病性试验结果显示,SPF鸡感染Mallard/CH/HLJ127/06后表现明显的临床症状,在感染鸡的脑、气管、肺脏、腺胃、盲肠扁桃体、肾脏和肝脏中均能够检测到病毒的RNA。本研究为进一步研究野鸟在NDV流行病学中的作用及对我国新城疫的防控提供了依据。

Wild birds are considered as the important natural host of Newcastle disease virus （NDV）, which plays a vital role in the transmission and evolution of NDV. The NDV isolate of Mallard/CH/HLJ127/06 was isolated from wild bird in Heilongjiang province in 2006. In this study, the NDV isolate was analyzed and determined by genetic evolution, antigenic relatedness, the virulence index and pathogenicity. The results showed the Mallard/CH/HLJ127/06 belonged to class II genotype VII. Fusion protein cleavage site of the NDV isolate was I12RRQKRFI17. The antigenic relatedness analysis results demonstrated that there was no significant antigenic difference among Mallard/CH/HLJ127/06 and representative genotype VII strains. The pathogenic index MDT （Mean time to lethality with minimal lethal ＂dose virus） of Mallard/CH/HLJ127/06 was 68hrs and the ICPI （Intracerebral pathogenicity index） was 1.975. Pathogenicity tests showed that SPF chickens infected with the NDV isolate displayed apparently clinical signs of Newcastle disease and virus RNA was detected in brain, trachea, lung, proventriculus, cecal tonsil, kidney and liver from infected chickens. Our results provide insights into the roles of wild birds in the NDV epidemiology and the prevention and control of Newcastle disease in China.