本研究对我国首次分离获得的牛源牛病毒性腹泻病毒(BVDV)毒株Changchun 184(CC-184)和猪源牛病毒 性腹泻病毒ZM-95进行了遗传衍化关系研究。选择主要抗原E2基因为研究对象,首先应用RT-PCR及套式PCR 克隆得到CC-184和ZM-95的E2片段,通过序列测定发现CC-184和ZM-95 E2基因长度分别为1,122bp和1, 125bp,各自编码374和375个氨基酸残基。核酸序列同源性比较和系统发生分析表明2株病毒均属于BVDV-1, CC-184与Osloss亲缘关系最近,都属于已有的b基因亚型,其E2基因同源性达91．8％。而ZM-95的E2基因有 一个特征性的变异区,包含一个密码子序列插入,这一变异区编码了一段有别于其他瘟病毒的五肽氨基酸序列 HYKKK。结果还表明ZM-95与BVDV-1现有的5个基因亚型的亲缘关系均较远,E2基因同源性最高(与Oregon c24v)只有72．4％。而BVDV-1亚型内毒株间的同源性大于85％,亚型间的同源性在69％～75％之间,充分说明 ZM-95是BVDV-1中一个新发现的基因亚型。通常认为猪源BVDV来源于牛,应该与牛源BVDV有十分近的遗 传关系,但是本研究发现ZM-95与其他已知牛源BVDV较低的基因同源性说明猪源BVDV还具有独立的遗传衍 化与传播来源的可能性。

Two earlier Chinese isolates of bovine viral diarrhea virus , bovine CC-184 and pig ZM-95 were phylogenetically analyzed. The E2 gene encoding a major antigenic was obtained by reverse transcription polymerase chain reaction (RT-PCR) and nest-PCR. Sequencing results showed that the E2 genes of CC-184 and ZM-95 are 1122 and 1125 nucleotides in length, encoding 374 and 375 amino acids, respectively. Sequence comparison and phylogenetic analyses demonstrated that both isolates fall into the BVDV-1 group and distant from other Pestiviruses such as BVDV-2, Border disease virus (BDV) and Classical swine fever virus (CSFV). The E2 gene of CC-184 had the highest identity (91.8%) with its homologue in the Osloss strain. However, the E2 gene of ZM-95 is significantly divergent from other known Pestiviruses, with the highest sequence identity of 72. 4% to strain Oregon c24v. Furthermore, isolate ZM-95 addressed significant evolution distance compared with the other established subgroups of BVDV-1, as indicated by phylog