摘要
对日本血吸虫中国大陆株湖南、湖北、江西、安徽、四川、云南隔离群以及一个实验室传代品系从基因水平进行了多态性研究。首先，在用PCR-SSCP技术分析了285rDNA-D2高变区基础上，测定了该区安徽和云南隔离群的DNA序列；其次，用PCR获得了含有ITS的rDNA片段，并对其进行了酶切位点重复序列的多态性分析；最后，用RAPD技术分析了全基因组DNA的多态性。结果表明，安徽与云南隔离群的285rDNA-D2区序列仅有2个碱基的差异，碱基相同率达99．7％，大大高于与日本血吸虫菲律宾株的相同率87％，可以解释为什么7个隔离群D2区单链构象完全一致的原因；ITS的8种酶切图谱显示共有58条DNA片段，有差异者仅3条，占5．2％；对随机扩增的284个片段的分析显示7个隔离群的平均遗传距离D＝0．22，四川和云南间最小（D=0．13），安徽和云南间最大（D=0．3）。通过由点到面的研究及综合评估认为日本血吸虫中国大陆株虽然存在一定程度的点突变和多态性差异，但变异的程度较小，具有相对的遗传稳定性。由于我国血吸虫病流行区分布范围广，各地流行特点不尽相同，因此对日本血吸虫中国大陆株遗传变异的研究不仅有助于种下分类，更有利于流行病学研究及防治对策的制订。
In order to analyze the interspecies diversity and the extent of diversityamong Schistosoma japonicum Chinese mainland strains, the genetic variation on genelevel among 6 isolates collected from Jiangxi, Hunan, Hubei, Anhui, Sichuan, Yunnanand a cultured isolate from a laboratory were studied using molecular biologicaltechnique. There were only two different bases at position 112 and 143 in 536bpsequence of 28S rDNA-D2 domain between Anhui and Yunnan isolates, thehomology was 99.6%. The result could be explained the reason of why the migrationrates of single chain 28S rDNA-D2 domain among the above 7 isolates were thesame completely in PCR-SSCP. However, comparing with the sequences of thePhilippine isolate of S japonicum, S mansoni and S aematobium, there were 6, 94and 93 different bases and the homologies were 98.9, 82.5 and 82.7 Per centseparately. With 8 restriction endonucleases to analyze the ITS of rDNA obtained byPCR from the 7 isolates, the results showed that only 3 minor bands were different,e.g. 5.3% of total 58 fragments. It was suggested that the ITS of rDNA among 7isolates were highly conserved. Using randomly amplified polymorphic DNA (RAPD)to analyze the genetic diversity of the genomes of the 7 isolates, the average geneticdistance (D) calculated from total 284 amplified fragments was 0.22. The maximum Dwas 0.30 and existed between Anhui and Yunnan isolates. The minimum D was 0.13and existed between Sichuan and Yunnan isolates. The clustering analysis of geneticdistances showed that the 7 isolates could be gathered in one group. From abovethree results, it could be considered that the genetic diversity on gene level amongS japonicum Chinese mainland strains was very low.
