Spithill T W, Grumont R J
Mol Biochem Parasitol. 1984 Jun;12(2):217-36. doi: 10.1016/0166-6851(84)90137-3.
Molecular analysis of kinetoplast deoxyribonucleic acid (kDNA) minicircles has permitted the genotypic characterization of pathogenic isolates of Leishmania species. The apparent size in agarose gels of unit-length minicircles released by EcoRI digestion of kDNA networks is not conserved during speciation in this genus since the minicircles of strains and clones of L. major are smaller (710 base pairs, bp) than those found in certain strains of L. mexicana subspecies (820 bp), L. donovani (825, 865 bp) or L. tropica (900, 930 bp). EcoRI-cut minicircles within any one species of Leishmania are heterogeneous in mobility during electrophoresis in acrylamide gels. Schizodeme analysis of minicircles reveals a high degree of sequence divergence in kDNA with the degree of microheterogeneity varying between species. This sequence divergence allows the discrimination of closely related clones and strains within a given species. Southern blot hybridization reveals that overall minicircle sequence homology is conserved among clones and strains of one species (L. major or L. tropica) but not between different species. This property of minicircle DNA permits the use of kDNA probes as a species-specific diagnostic test for the identification of Leishmania isolates. The analysis of kDNA from two L. tropica strains isolated at 14 year intervals from a patient with leishmaniasis recidivans has shown that the two strains are closely related, suggesting that the individual suffered the cutaneous disease as a result of a resurgence of the same parasite which caused the initial infection. The differences in the properties of kDNA from the L. tropica and L. major strains studied support the taxonomic separation of L. tropica and L. major into distinct species.
对动基体脱氧核糖核酸（kDNA）微环的分子分析有助于对利什曼原虫属致病分离株进行基因分型。由于硕大利什曼原虫菌株和克隆的微环比墨西哥利什曼原虫亚种某些菌株（820个碱基对，bp）、杜氏利什曼原虫（825、865 bp）或热带利什曼原虫（900、930 bp）中的微环小，因此通过kDNA网络的EcoRI消化释放的单位长度微环在琼脂糖凝胶中的表观大小在该属物种形成过程中并不保守。利什曼原虫任何一个物种内经EcoRI切割的微环在丙烯酰胺凝胶电泳过程中的迁移率是异质的。微环的裂殖体型分析显示kDNA存在高度的序列差异，微异质性程度因物种而异。这种序列差异使得能够区分给定物种内密切相关的克隆和菌株。Southern印迹杂交显示，一个物种（硕大利什曼原虫或热带利什曼原虫）的克隆和菌株之间微环序列的总体同源性是保守的，但不同物种之间则不然。微环DNA的这一特性使得kDNA探针可作为一种物种特异性诊断测试用于鉴定利什曼原虫分离株。对间隔14年从一名复发性利什曼病患者分离出的两株热带利什曼原虫的kDNA分析表明，这两株菌株密切相关，提示该个体患皮肤疾病是由引起初始感染的同一寄生虫复发所致。所研究的热带利什曼原虫和硕大利什曼原虫菌株kDNA特性的差异支持将热带利什曼原虫和硕大利什曼原虫分类为不同的物种。
