我国部分地区鸡贫血病病毒全基因组核苷酸序列的比较与分析

Comparison and analysis of the complete genomic nucleotide sequences of chicken anemia virus isolates from some regions of China

本研究测定了3个鸡贫血病病毒(Chinken anemia virus,CAV)国内分离株及12个直接来源于临床样品的CAV毒株全基因组序列,结果表明15个CAV毒株的全基因组长度和结构与已报道的其它CAV毒株一致,长度均为2298nt,包含有3个重叠的ORFs。与GenBank发表的13个毒株序列进行序列比较发现,所有毒株核苷酸序列的相似性在95.2%～99.5%之间,CAV全基因组序列有2个高度变异区(HVR),分别位于1033nt～1470nt和1858nt～2193nt。CAVORF3变异度最高,其5'端2/5处和3'端2/5～1/5处为2个高度变异区。ORF2变异度也较高,主要出现在5'端1/4处,ORF1最为保守。以CAV全基因组核苷酸序列和ORF3核苷酸序列为基础分别构建的CAV毒株分子进化树,均可以将全部CAV毒株划分为2个基因群。我国部分地区分离的大多数毒株,属基因Ⅰ群,与德国Cux-1等主要流行毒株有较为相近的亲缘关系;其它CAV国内毒株,属基因Ⅱ群,与日本G6株和TR20株有着更为相近的关系。

The complete genomic sequences of three CAV strains and twelve clinical isolates were determined. The genome contained 2 298 nucleotides and three overlapping ORFs that have been identified in other CAV isolates. Sequence comparion revealed 95.2 %-99.5 % nucleotide similarities among the fifteen strains and other thirteen CAV genomic sequences from GenBank. Two highly variable regions （HRV） were identified in ORF3, one located in position 1 033 nt-1 470 nt at the 5＇ terminus and the other in 1 858 nt-2 193 nt at the 3＇ terminus. ORFI was relatively more conservative than ORF2 and ORF3. Phylogenetic tree analysis showed that all CAV isolates could be classified into two distinct genetic subgroups. Most of the CAV isolates from China were genetically close to Cux-1 isolated from German and could be classified as subgroup Ⅰ ; the other isolates were closer with Japanese G6 and TR20 isolates, which were classified as subgroup Ⅱ.