Novati S, Sironi M, Granata S, Bruno A, Gatti S, Scaglia M, Bandi C
Laboratorio di Parassitologia Clinica, Università di Pavia, Italy.
Parasitology. 1996 Apr;112 ( Pt 4):363-9. doi: 10.1017/s0031182000066592.
Since 1993, strains of Entamoeba histolytica sensu lato have been assigned to 2 species on the basis of clinical, biochemical, immunological and genetic evidence: the pathogenic strains to E. histolytica sensu stricto, the non-pathogenic strains to Entamoeba dispar. Analysis of the gene encoding for the small subunit ribosomal RNA (SSU rDNA) supports the existence of 2 species. However, while 3 whole SSU rDNA sequences are available in the data bases for E. histolytica, only a partial sequence has been published for E. dispar. Here we report a SSU rDNA sequence for E. dispar. Compared to those of E. histolytica, this sequence shows 1.7% nucleotide substitutions. On the basis of our rDNA data, 2 primers were designed to produce polymerase chain reaction (PCR) amplification from both E. histolytica and E. dispar. Primer specificity for the 2 amoebae was assessed both theoretically against the data bases, and experimentally against a collection of eukaryotic and prokaryotic DNAs. The amplified stretch encompasses a polymorphic Dde I restriction site which allows, after cleavage of the fragment, E. histolytica and E. dispar to be distinguished. The reliability of this method of identification was assessed comparing the results with those based on classic isoenzyme analysis.
自1993年以来，基于临床、生化、免疫和遗传证据，溶组织内阿米巴复合体的菌株被分为2个种：致病菌株归为狭义的溶组织内阿米巴，非致病菌株归为迪斯帕内阿米巴。对编码小亚基核糖体RNA（SSU rDNA）的基因分析支持这2个种的存在。然而，虽然数据库中有3个完整的溶组织内阿米巴SSU rDNA序列，但迪斯帕内阿米巴仅发表了一个部分序列。在此我们报道迪斯帕内阿米巴的一个SSU rDNA序列。与溶组织内阿米巴的序列相比，该序列显示有1.7%的核苷酸替换。基于我们的rDNA数据，设计了2条引物用于从溶组织内阿米巴和迪斯帕内阿米巴中进行聚合酶链反应（PCR）扩增。通过理论上与数据库比对以及实验上与一系列真核和原核DNA比对，评估了这2条引物对这2种阿米巴的特异性。扩增片段包含一个多态性的Dde I限制性酶切位点，片段经酶切后可区分溶组织内阿米巴和迪斯帕内阿米巴。通过将结果与基于经典同工酶分析的结果进行比较，评估了这种鉴定方法的可靠性。
