The taxonomic and phylogenetic relationships of Trypanosoma vivax from South America and Africa
The taxonomic and phylogenetic relationships of Trypanosoma vivax from South America and Africa
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DOI：
10.1017/s0031182006000254
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发表时间：
2006-08-01
期刊：
影响因子：
2.4
通讯作者：
Teixeira, M. M. G.
中科院分区：
文献类型：
--
作者：
Cortez, A. P.;Ventura, R. M.;Teixeira, M. M. G.
间日锥虫的分类学和系统发育关系存在争议。一般认为，南美、东非和西非分离株可归类为间日疟原虫的亚种或近缘种。这是第一个将南美分离株（巴西和委内瑞拉）与西非/东非间日疟原虫分离株进行比较的系统发育研究。使用核糖体序列的系统发育将所有间日锥虫分离株紧密地定位在包含所有唾液锥虫的进化枝的外围。使用不同的序列数据集（SSU、SSU 加 5.8S 或整个 ITS rDNA），在所有推断的系统发育中观察到间日疟原虫分支内分离株的相同分支。来自巴西、委内瑞拉和西非（尼日利亚）的间日疟原虫密切相关，证实了南美间日疟原虫的西非起源，而这些分离株与所分析的东非分离株（肯尼亚）之间存在很大的遗传距离。从巴西牛中分离出来的无症状或表现出不同病理学的菌株具有高度同质性。这项研究没有揭示将西非和南美分离株分为不同物种/亚种的显着多态性，并表明非洲间日锥虫和整个锥虫亚属（Duttonella）的复杂性可能比之前认为的要高。
The taxonomic and phylogenetic relationships of Trypanosoma vivax are controversial. It is generally suggested that South American, and East and West African isolates could be classified as subspecies or species allied to T. vivax. This is the first phylogenetic study to compare South American isolates (Brazil and Venezuela) with West/East African T. vivax isolates. Phylogeny using ribosomal sequences positioned all T. vivax isolates tightly together on the periphery of the clade containing all Salivarian trypanosomes. The same branching of isolates within T. vivax clade was observed in all inferred phylogenies using different data sets of sequences (SSU, SSU plus 5.8S or whole ITS rDNA). T. vivax from Brazil, Venezuela and West Africa (Nigeria) were closely related corroborating the West African origin of South American T. vivax, whereas a large genetic distance separated these isolates from the East African isolate (Kenya) analysed. Brazilian isolates from cattle asymptomatic or showing distinct pathology were highly homogeneous. This study did not disclose significant polymorphism to separate West African and South American isolates into different species/subspecies and indicate that the complexity of T. vivax in Africa and of the whole subgenus Trypanosoma (Duttonella) might be higher than previously believed.