狐源犬瘟热病毒的分离鉴定及H基因遗传变异分析

Isolation and identification of canine distemper virus from fox and the genetic variability analysis of its H gene

为分离鉴定以及分析我国毛皮动物中流行的犬瘟热病毒(CDV),本研究采用Vero-SLAM细胞从山东省荣成市某养殖场疑似CDV感染狐狸的肺脏样品中分离到1株病毒,经RT-PCR、病毒形态观察、间接免疫荧光试验、动物回归试验等鉴定,确认该分离株为CDV野毒株,命名为SD(14)7。对其H基因进行克隆和测序分析,结果表明,SD(14)7与其他Asia-1型野毒株H基因的相似性为97.1%~99.6%,其中与SD(12)1和SD(13)5的相似性最高,分别为99.5%和99.6%,与CDV强毒株He Bei株的相似性为97.8%,与疫苗株CDV3、Onderstepoort、Snyder Hill以及ConvacH基因的相似性为90.4%~90.9%。H基因系统发育树分析表明,SD(14)7株属于Asia-1型,为我国当前流行的野毒株。氨基酸序列分析显示,SD(14)7株H蛋白发生了I542N和Y549H突变,在aa542~aa544位增加了1个潜在的N-糖基化位点,潜在的N-糖基化位点数增加至10个。本研究为CDV毒力变化和宿主嗜性的研究提供了参考依据。

Canine distemper virus （CDV） was isolated from lung sample of a fox from Rongcheng, Shandong province. Identification of RT-PCR, virus morphology observation, indirect immunofluorescence test and animal regression proved the isolate was a wild strain of CDV and named SD（14）7. After cloning and sequencing analysis the H gene of SD（14）7, SD（14）7 strain and other Asia-1 wild strains exhibited high similarity （97.1%-99.6%） and had the most similarity with SD（I 2）1 （99.5%） and SD（I 3）5 （99.6%）, however, showed low similarity when compared with CDV vaccine （CDV3, Onderstepoort, Snyder Hill and Convae） （90.4%-90.9%）. Based on the phylogenetic analysis of the complete H gene of SD（14）7, SD （14）7 was characterized as Asia-1 genotype, which was the dominant prevalent genotype currently in China. In addition, the H protein of SD（14）7 had amino acid mutations as I^ZN and Y^I-I and generated a potentially novel N-glycosylation site. These findings support the study on virulence change and host tropism of CDV.