马传染性贫血病毒疫苗株EIAV_(FDDV)穿膜蛋白GP45的截短突变

为研究中国马传染性贫血病毒(EIAV)弱毒疫苗致弱过程中基因组的进化特征,作者对EIAVFDDV前病毒的囊膜基因env进行了分析。使用PCR方法体外扩增EIAVFDDV前病毒DNA的env,并随机挑取PCR的阳性克隆子进行测序和序列比对分析。结果表明,随机挑取的PCR阳性克隆中,29/30的克隆子在第2 128-2 130位核苷酸处存在TGG→TGA(翻译中止密码)的突变。该基因对应的EIAV穿膜蛋白gp45的氨基酸数在突变株中较未截短株中减少154,变成259个aa。对EIAVFDDV进行Western blot分析时发现,EIAVDLV45 ku的gp45条带被约35 ku的条带取代。由此推测,EIAVFDDV疫苗株绝大多数病毒颗粒的gp45是截短型。对该代次疫苗株免疫马匹第15和40天体内EIAV前病毒DNA和基因组RNA的序列进行分析,结果表明该截短毒株具有在体内和体外进行复制的能力。由于已有研究表明细胞嗜性改变与gp45的截短有关,因此,推断EIAVFDDV的gp45的截短是其适应在体外培养的驴胎皮肤细胞上复制传代的结果。综上所述,本研究发现EIAVFDDV的gp45存在高比例截短突变,证明该截短突变毒株具有在体内和体外进行复制的能力。但该截短突变是否可通过改变EIAVFDDV在免疫马体内的细胞嗜性,进而影响其毒力和免疫原性,还有待进一步验证。

The Truncated Mutation of Transmembrane Protein(TM or gp45) Identified in Fetal Donkey Dermal Cells-Adapted Viral Strains(EIAVFDDV) of Chinese Equine Infectious Anemia Virus(EIAV) Attenuated Vaccine

To investigate the genomic evolution of EIAV vaccine strains during attenuation,we analyzed the sequence of env in provirus of EIAVFDDV.After amplifying env in provirus DNA of EIAVFDDV by using PCR,some positive T-A clones were selected randomly to sequence and analyze.A mutation from TGG to TGA,a premature stop codon,was detected at the position of 2 128-2 130 nt of the env in 29 of 30 randomly selected clones of env.This mutation causes a truncated transmembrane protein(TM,also termed as gp45) at the 262t...