The evolution of two Trypanosoma cruzi subgroups inferred from rRNA genes can be correlated with the interchange of American mammalian faunas in the Cenozoic and has implications to pathogenicity and host specificity
The evolution of two Trypanosoma cruzi subgroups inferred from rRNA genes can be correlated with the interchange of American mammalian faunas in the Cenozoic and has implications to pathogenicity and host specificity
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DOI：
10.1016/s0166-6851(99)00155-3
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发表时间：
1999-11-30
影响因子：
1.5
通讯作者：
Zingales, B
中科院分区：
文献类型：
--
作者：
Briones, MRS;Souto, RP;Zingales, B
查加斯病的病原体克氏锥虫分为两个高度不同的遗传亚群，谱系1和谱系2，其包括从人类、昆虫载体和森林哺乳动物分离的所有分型菌株。这两个T.克鲁兹血统及其鉴定的临床重要性一直是激烈辩论的主题。通过分子系统发育分析，我们发现两个T. cruzi谱系相当于利什曼原虫属和内锥虫属之间的距离。此外，我们证实，T。rangeli与T. cruzi比T.利用人布氏锥虫的rDNA序列，rangeli基于小亚基rDNA序列的系统发育树进一步表明，这两个T。克鲁兹人的血统在8800万年到3700万年前出现分歧。我们假设谱系2是南美洲的土著，而谱系1是在上新世（500万年前）与美洲相连后，沿着北美胎盘哺乳动物，或在渐新世（3800万年前）与豚鼠形啮齿动物和灵长类动物相连后，最近才被引入南美洲的。这可以解释T. cruzi谱系2与有袋动物和谱系1与人类疾病。这两个T。克鲁齐世系很可能是不同的物种，或至少是亚种，因为它们具有不同的生态和流行病学特征，而且估计独立进化的时间很长。(C)1999 Elsevier Science B.V.保留所有权利。
The agent of Chagas disease, Trypanosoma cruzi, is divided into two highly divergent genetic subgroups, lineages 1 and 2, which include all typed strains isolated from humans, insect vectors, and sylvatic mammals. The evolutionary origin of these two T. cruzi lineages and the clinical importance of their identification, have been the subject of intense debate. Here, using molecular phylogenetic analysis, we found that the distance between the two T. cruzi lineages is equivalent to the distance between genera Leishmania and Endotrypanum. Also, we confirmed that T. rangeli is more closely related to T. cruzi than to T. brucei using the rDNA sequence from a human strain of T. rangeli. Phylogenetic trees based on small subunit rDNA sequences further suggest that the two T. cruzi lineages diverged between 88 and 37 million years (Myr) ago. We hypothesize that lineage 2 is indigenous to South America while lineage 1 has been introduced to South America recently, along with North American placental mammals, after the connection of the Americas in the Pliocene (5 Myr ago) or with caviomorph rodents and primates in the Oligocene (38 Myr ago). This would explain the preferential association of T. cruzi lineage 2 with marsupials and of lineage 1 with human disease. These two T. cruzi lineages are likely to be distinct species, or at least subspecies, because of their different ecological and epidemiological traits and estimated long period of independent evolution. (C) 1999 Elsevier Science B.V. All rights reserved.