Analyses of 32 loci clarify phylogenetic relationships among Trypanosoma cruzi lineages and support a single hybridization prior to human contact.
Analyses of 32 loci clarify phylogenetic relationships among Trypanosoma cruzi lineages and support a single hybridization prior to human contact.
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DOI：
10.1371/journal.pntd.0001272
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发表时间：
2011-08
影响因子：
3.8
通讯作者：
Machado CA
中科院分区：
文献类型：
--
作者：
Flores-López CA;Machado CA
恰加斯病的病原克氏锥虫的遗传多样性传统上被分为两大类，克氏锥虫I和II，根据最近提出的命名法对应于离散的分型单位TcI和TcI - vi。克氏锥虫的两个主要类群似乎在重要的生物学特征上有所不同，因此被认为代表了与流行病学研究和预防发展有关的一种自然划分。为了了解恰加斯病的不同表现与克鲁兹锥虫菌株变异性之间的潜在联系，有必要对克鲁兹锥虫的进化史进行正确的重建。利用32个非连锁位点的核苷酸序列（共26个碱基）重建了代表已知克氏锥虫遗传变异性的菌株的进化史。深入的系统发育分析表明，克氏锥虫在两个主要谱系中的原始分类并不能反映其进化史，而且在该物种的历史中，只有一个主要的和最近的杂交事件有强有力的证据。此外，使用贝叶斯方法对分化时间的估计表明，目前现存的克氏锥虫谱系在最近的300万年内分化，而导致杂交谱系TcV和TcVI的主要杂交事件发生在不到100万年前，远远早于克氏锥虫与人类在南美洲的接触。所描述的克氏锥虫六个主要遗传分支之间的系统发育关系应作为有针对性的流行病学和预防研究的指导方针。我们建议重新考虑以前的研究结论是很重要的，这些研究试图揭示两个最初定义的克氏锥虫主要谱系之间的重要生物学差异，特别是如果这些结论是从单个或少数菌株中获得的。克氏锥虫是导致南美锥虫病的原生动物寄生虫，恰加斯病是拉丁美洲的一个主要健康问题。该寄生虫的遗传多样性传统上分为两大类群：克氏锥虫I和II，可进一步分为6个主要遗传亚群（TcI-TcVI亚群）。克氏锥虫I型和II型似乎在重要的生物学特征上有所不同，被认为代表了与流行病学研究和预防发展相关的一种自然区分。正确重建克氏锥虫的进化史对于理解克氏锥虫的遗传和表型变异与恰加斯病不同表现之间的潜在联系至关重要。在这里，我们展示了利用超过26kb的对齐序列数据对克氏锥虫进行全面系统发育分析的结果。我们提供了强有力的证据，证明T. cruzi II （TcII-VI）不是一个自然进化类群，而是一个副进化谱系，并且所有主要的T. cruzi谱系都是在最近（< 300万年前[mya]）进化的。此外，序列数据与该物种最近（< 1亿年前）发生的一次主要杂交事件相一致，但早在克氏锥虫与南美洲人类接触之前。
The genetic diversity of Trypanosoma cruzi, the etiological agent of Chagas disease, has been traditionally divided in two major groups, T. cruzi I and II, corresponding to discrete typing units TcI and TcII-VI under a recently proposed nomenclature. The two major groups of T. cruzi seem to differ in important biological characteristics, and are thus thought to represent a natural division relevant for epidemiological studies and development of prophylaxis. To understand the potential connection between the different manifestations of Chagas disease and variability of T. cruzi strains, it is essential to have a correct reconstruction of the evolutionary history of T. cruzi. Nucleotide sequences from 32 unlinked loci (>26 Kilobases of aligned sequence) were used to reconstruct the evolutionary history of strains representing the known genetic variability of T. cruzi. Thorough phylogenetic analyses show that the original classification of T. cruzi in two major lineages does not reflect its evolutionary history and that there is only strong evidence for one major and recent hybridization event in the history of this species. Furthermore, estimates of divergence times using Bayesian methods show that current extant lineages of T. cruzi diverged very recently, within the last 3 million years, and that the major hybridization event leading to hybrid lineages TcV and TcVI occurred less than 1 million years ago, well before the contact of T. cruzi with humans in South America. The described phylogenetic relationships among the six major genetic subdivisions of T. cruzi should serve as guidelines for targeted epidemiological and prophylaxis studies. We suggest that it is important to reconsider conclusions from previous studies that have attempted to uncover important biological differences between the two originally defined major lineages of T. cruzi especially if those conclusions were obtained from single or few strains. Trypanosoma cruzi is the protozoan parasite that causes Chagas disease, a major health problem in Latin America. The genetic diversity of this parasite has been traditionally divided in two major groups: T. cruzi I and II, which can be further divided in six major genetic subdivisions (subgroups TcI-TcVI). T. cruzi I and II seem to differ in important biological characteristics, and are thought to represent a natural division relevant for epidemiological studies and development of prophylaxis. Having a correct reconstruction of the evolutionary history of T. cruzi is essential for understanding the potential connection between the genetic and phenotypic variability of T. cruzi with the different manifestations of Chagas disease. Here we present results from a comprehensive phylogenetic analysis of T. cruzi using more than 26 Kb of aligned sequence data. We show strong evidence that T. cruzi II (TcII-VI) is not a natural evolutionary group but a paraphyletic lineage and that all major lineages of T. cruzi evolved recently (<3 million years ago [mya]). Furthermore, the sequence data is consistent with one major hybridization event having occurred in this species recently (< 1 mya) but well before T. cruzi entered in contact with humans in South America.
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影响因子：
64.8
作者：
Gaunt, MW;Yeo, M;Miles, MA
通讯作者：
Miles, MA
DOI：
10.1111/j.1096-0031.1996.tb00196.x
发表时间：
1994-09-01
期刊：
CLADISTICS-THE INTERNATIONAL JOURNAL OF THE WILLI HENNIG SOCIETY
影响因子：
--
作者：
FARRIS, JS;KALLERSJO, M;BULT, C
通讯作者：
BULT, C
影响因子：
1.5
作者：
Briones, MRS;Souto, RP;Zingales, B
通讯作者：
Zingales, B
影响因子：
2.4
作者：
Barnabé, C;Brisse, S;Tibayrenc, M
通讯作者：
Tibayrenc, M
影响因子：
2.1
作者：
Broutin, H;Tarrieu, F;Barnabé, C
通讯作者：
Barnabé, C