Schwenkenbecher Jan M, Wirth Thierry, Schnur Lionel F, Jaffe Charles L, Schallig Henk, Al-Jawabreh Amer, Hamarsheh Omar, Azmi Kifaya, Pratlong Francine, Schönian Gabriele
Institute of Microbiology and Hygiene, Humboldt University, Charité Campus Mitte, Dorotheenstr. 96, D-10117 Berlin, Germany.
Int J Parasitol. 2006 Feb;36(2):237-46. doi: 10.1016/j.ijpara.2005.09.010. Epub 2005 Oct 14.
The current rapid spread of leishmaniases caused by Leishmania tropica and the complexity of its clinical spectrum call for this parasite's epidemiological and evolutionary investigation. Evaluation of its population structure by isoenzyme electrophoresis and previous molecular biological analysis has proved difficult. In this study, we used 21 microsatellite loci to type 117 strains from different African and Asian locations. Eighty-one different genotypes were found. A genetic bottleneck supported by a gradient in the number of alleles and consistent with the geographical structure of the Middle East suggests an African origin of this species. A Bayesian approach identified 10 genetic clusters that correlated predominantly with geographical origin. The strains in the 'Asia' cluster form a very heterogeneous sub-population, with a varied but inter-related genotype that is geographically very widely dispersed and consistent with anthroponotic transmission of the parasite. The other nine clusters were more homogenous. The propagation of L. tropica appears to be predominantly clonal. In Africa and the Middle East, anthroponotic and zoonotic systems of distribution may contribute to the development of overlapping, genetically distinct populations of L. tropica.
由热带利什曼原虫引起的利什曼病目前正在迅速传播，其临床谱又很复杂，因此需要对这种寄生虫进行流行病学和进化研究。通过同工酶电泳和以往的分子生物学分析来评估其种群结构已被证明是困难的。在本研究中，我们使用21个微卫星位点对来自不同非洲和亚洲地点的117株菌株进行分型。共发现81种不同的基因型。等位基因数量的梯度支持了遗传瓶颈现象，且这与中东的地理结构一致，表明该物种起源于非洲。贝叶斯方法确定了10个遗传簇，这些遗传簇主要与地理起源相关。“亚洲”簇中的菌株形成了一个非常异质的亚群，具有多样但相互关联的基因型，在地理上分布非常广泛，这与该寄生虫的人传人传播一致。其他九个簇则更为同质。热带利什曼原虫的传播似乎主要是克隆性的。在非洲和中东，人传人和动物传人的分布系统可能导致热带利什曼原虫出现重叠的、基因不同的种群。
