Fraga Jorge, Fernández-Calienes Aymé, Montalvo Ana Margarita, Maes Ilse, Deborggraeve Stijn, Büscher Philippe, Dujardin Jean-Claude, Van der Auwera Gert
Parasitology Department, Institute of Tropical Medicine Pedro Kouri, La Havana, Cuba.
Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium.
Infect Genet Evol. 2016 Sep;43:165-72. doi: 10.1016/j.meegid.2016.05.016. Epub 2016 May 13.
Trypanosome evolution was so far essentially studied on the basis of phylogenetic analyses of small subunit ribosomal RNA (SSU-rRNA) and glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) genes. We used for the first time the 70kDa heat-shock protein gene (hsp70) to investigate the phylogenetic relationships among 11 Trypanosoma species on the basis of 1380 nucleotides from 76 sequences corresponding to 65 strains. We also constructed a phylogeny based on combined datasets of SSU-rDNA, gGAPDH and hsp70 sequences. The obtained clusters can be correlated with the sections and subgenus classifications of mammal-infecting trypanosomes except for Trypanosoma theileri and Trypanosoma rangeli. Our analysis supports the classification of Trypanosoma species into clades rather than in sections and subgenera, some of which being polyphyletic. Nine clades were recognized: Trypanosoma carassi, Trypanosoma congolense, Trypanosoma cruzi, Trypanosoma grayi, Trypanosoma lewisi, T. rangeli, T. theileri, Trypanosoma vivax and Trypanozoon. These results are consistent with existing knowledge of the genus' phylogeny. Within the T. cruzi clade, three groups of T. cruzi discrete typing units could be clearly distinguished, corresponding to TcI, TcIII, and TcII+V+VI, while support for TcIV was lacking. Phylogenetic analyses based on hsp70 demonstrated that this molecular marker can be applied for discriminating most of the Trypanosoma species and clades.
迄今为止，锥虫的进化主要是基于对小亚基核糖体RNA（SSU-rRNA）和糖体甘油醛-3-磷酸脱氢酶（gGAPDH）基因的系统发育分析进行研究的。我们首次使用70kDa热休克蛋白基因（hsp70），基于来自65个菌株的76个序列的1380个核苷酸，研究了11种锥虫之间的系统发育关系。我们还基于SSU-rDNA、gGAPDH和hsp70序列的组合数据集构建了系统发育树。除泰勒锥虫和朗氏锥虫外，所获得的聚类与感染哺乳动物的锥虫的节和亚属分类相关。我们的分析支持将锥虫物种分类为进化枝而非节和亚属，其中一些是多系的。识别出九个进化枝：鲤锥虫、刚果锥虫、克氏锥虫、格雷锥虫、刘易斯锥虫、朗氏锥虫、泰勒锥虫、活泼锥虫和布氏锥虫属。这些结果与该属系统发育的现有知识一致。在克氏锥虫进化枝内，可以清楚地区分出三组克氏锥虫离散型单元，分别对应于TcI、TcIII和TcII+V+VI，而缺乏对TcIV的支持。基于hsp70的系统发育分析表明，这种分子标记可用于区分大多数锥虫物种和进化枝。
