广西两地旋毛虫分离株5SrDNA序列分析

Study on 5S rDNA Sequence of Two Isolates of Trichinella from Guangxi

目的应用5SrDNA序列分析,鉴定广西德保、南丹两地旋毛虫分离株。方法PCR扩增2个分离株5SrDNA片段,并对扩增产物进行测序;用相关软件分析序列的同源性、遗传距离,同时构建系统发生树,并与GenBank中旋毛虫相应基因序列进行比较。结果广西德保、南丹2地旋毛虫分离株和GenBank中Trichinella spiralis的5SrDNA碱基序列长度相同,为695bp;变异位点4个,与T.spiralis的相似度分别为99.0%和99.1%,与GenBank中其他相应基因的相似度低于94.2%,2个分离株之间的相似度为98.8%。2个分离株之间及与T.spiralis间的遗传距离最小,均为0.014;而与其他旋毛虫的遗传距离均大于0.056;用邻接法(N-J法)和最大简约法(MP法)构建的2个系统发生树中,2个分离株与T.spiralis位于同一分支,自引导值分别为96及99。结论初步鉴定广西德保和南丹旋毛虫分离株均为T.spiralis。

Objective To analyze 5S ribosomal DNA （5S rDNA） sequences of two Trichinella isolates from Guangxi. Methods The fragments of 5S rDNA were obtained by PCR from the isolates of Debao and Nandan, and sequencing was made for the PCR products. Homogeneity, genetic distance matrix and phylogenetic tree were analyzed by related software. 5S rDNA sequences of the two isolates were compared separately with those of Trichinella species in GenBank. Results 5S rDNA sequences of three Trichinella isolates （Debao, Nandan and T.spira!is） showed the same length at 695 bp. There were 4 variable positions. The homogeneities of Debao and Nandan isolates with T. spiralis were 99.0% and 99.1% respectively. The homogeneities between Debao isolate and Nandan isolate was 98.8%. Compared with other Trichinella isolates in GenBank, they were all less than 94.2%. The evolutionary distance among isolates of Debao and Nandan and T.spiralis was 0.014. Meanwhile, the evolutionary distances between the Guangxi isolates and other Trichinella isolates in GenBank were more than 0.056. Phylogenetic tree analysis revealed that two isolates of Guangxi and T.spiralis located at the same node, revealing a close relationship. Bootstrap confidence values in two phylogenetic trees were 96 and 99, respectively. Conclusion The two Trichinella isolates of Guangxi show a high homogeneity with T.spiralis,locate at the same nodes in phylogenetic tree,suggesting that the Debao and Nandan Trichinella isolates be identified as T.spiralis.