猪瘟兔化弱毒疫苗株基因组的遗传变异分析

参照已发表的猪瘟病毒基因组序列设计了9对引物，用RT-PCR从猪瘟兔化弱毒疫苗株细胞培养物中扩增得到了覆盖猪瘟病毒基因组全长的9个cDNA片段，将所得cDNA片段分别克隆至pMD18-T载体中，经测序和拼接后，获得了猪瘟兔化弱毒疫苗株基因组全序列。序列分析表明，猪瘟兔化弱毒疫苗株基因组全长12310个碱基，其5’非编码区（5＇-NCR）和3＇-NCR分别由373和239个碱基组成，在3’末端有富含T的碱基插入，其间为1个大的开放阅读框架，编码3898个氨基酸残基的多聚蛋白，与国内外已发表的另外7个猪瘟兔化弱毒疫苗株基因组全序列相比，核苷酸同源性为98．7％～99．9％，氨基酸同源性为98．6％～99．9％。基因组全序列比较显示，猪瘟兔化弱毒疫苗株基因组在遗传上相当稳定。

Genetic variations of the genomic sequence of classical swine fever virus C-strain

Nine overlapping cDNA fragments covering the complete genomic RNA of classical swine fever virus (CSFV) C-strain (C-strain/HVRI) were cloned and sequenced, and the complete genomic sequence was assembled. The genome of C-strain/HVRI consists of 12 310 bp, and contains a large open reading frame encoding a polyprotein of 3 898 amino acids, which is flanked by two non-coding regions (NCRs), 373 bases on the 5'-end and 239 bases on the 3'-end. Homology comparison between the genomic sequence of C-strain/HVRI and other genomic sequences of C-strain showed 98.7 % to 99.9 % identities at nucleotide level, and 98.6 % to 99.9 % identities at amino acid level. A T-rich insertion in the 3'-NCR of C-strain/HVRI sequences was noted. Phylogenetic analysis based on the complete genomic sequences of 27 CSFV strains suggests C-strain is relatively genetically stable, representing a unique subgenotype.