西北部分地区猪蛔虫rDNAITS基因序列测定及遗传变异分析

Sequencing and Phylogenetic Analysis on rDNA ITS Genes of Ascaris suum isolates from Different Regions in Northwest China

为了摸清西北部分地区猪蛔虫内转录间隔区(ITS)的遗传变异特点,扩增了猪蛔虫ITS基因,进行测序,依据GenBank公布的ITS序列将测序结果截为ITS1、5.8S及ITS2三段,分析比对各段序列的差异性。结果显示,所有样品ITS序列长约1 000bp,其中ITS1、5.8S和ITS2的长度分别为450bp^453bp、159bp、272bp,种内差异分别为0~0.2%、0、0。基于ITS1的种系发育分析表明,23个猪蛔虫样品均位于同一分支,而与贝蛔属蛔虫分属两个不同分支。ITS1序列不能作为区分西北不同地区猪蛔虫的种内分子标记,但可以作为区分蛔属蛔虫与贝蛔属蛔虫的种间分子标记,研究结果为猪蛔虫的鉴定和分子流行病学调查提供了基础资料。

To illuminate the genetic variation characteristics of Ascaris suumisolated from different regions in northwest China,the internal transcription spacer（ITS）genes were amplified by using the PCR method with the conserved primers NC5/NC2.After the amplicons were cloned and sequenced,the sequencing results were divided into ITS1,5.8Sand ITS2 according to the public sequence in GenBank.And then those genes were compared and aligned to build phylogenetic tree.The results showed that the ITS genes of all A.suumsamples were amplified successfully with the length of 1 000 bp approximately,including 450bp-453 bp for ITS1,159 bp for 5.8Sand 272 bp for ITS2 and the intra-specific differences were 0-0.2% for ITS1,0for 5.8S,0for ITS2.Phylogenetic analysis displayed that all A.suumsamples were monophyletic groups and located in different clusters with the reference sequences of the genus Baylisascaris.Therefore,the ITS genes were not suitable to serve as molecular marker to distinguish the A.suumisolates from different regions in northwest China,but it can be used as intraspecific genetic marker to identify the genera Ascaris and Baylisascaris.Those findings may provide basic data for the identification and molecular epidemiology investigation of A.suum.