Marcili A, Lima L, Cavazzana M, Junqueira A C V, Veludo H H, Maia Da Silva F, Campaner M, Paiva F, Nunes V L B, Teixeira M M G
Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo (USP), SP, Brasil.
Parasitology. 2009 May;136(6):641-55. doi: 10.1017/S0031182009005861. Epub 2009 Apr 16.
We characterized 15 Trypanosoma cruzi isolates from bats captured in the Amazon, Central and Southeast Brazilian regions. Phylogenetic relationships among T. cruzi lineages using SSU rDNA, cytochrome b, and Histone H2B genes positioned all Amazonian isolates into T. cruzi I (TCI). However, bat isolates from the other regions, which had been genotyped as T. cruzi II (TC II) by the traditional genotyping method based on mini-exon gene employed in this study, were not nested within any of the previously defined TCII sublineages, constituting a new genotype designated as TCbat. Phylogenetic analyses demonstrated that TCbat indeed belongs to T. cruzi and not to other closely related bat trypanosomes of the subgenus Schizotrypanum, and that although separated by large genetic distances TCbat is closest to lineage TCI. A genotyping method targeting ITS1 rDNA distinguished TCbat from established T. cruzi lineages, and from other Schizotrypanum species. In experimentally infected mice, TCbat lacked virulence and yielded low parasitaemias. Isolates of TCbat presented distinctive morphological features and behaviour in triatomines. To date, TCbat genotype was found only in bats from anthropic environments of Central and Southeast Brazil. Our findings indicate that the complexity of T. cruzi is larger than currently known, and confirmed bats as important reservoirs and potential source of T. cruzi infections to humans.
我们对从亚马逊地区、巴西中部和东南部捕获的蝙蝠身上分离出的15株克氏锥虫进行了特征分析。利用小亚基核糖体DNA（SSU rDNA）、细胞色素b和组蛋白H2B基因对克氏锥虫谱系之间的系统发育关系进行分析，结果将所有亚马逊分离株归入克氏锥虫I型（TCI）。然而，本研究中采用基于小外显子基因的传统基因分型方法被基因分型为克氏锥虫II型（TC II）的其他地区的蝙蝠分离株，并未嵌套在任何先前定义的TCII亚谱系中，而是构成了一个新的基因型，命名为TCbat。系统发育分析表明，TCbat确实属于克氏锥虫，而不属于裂体锥虫亚属的其他密切相关的蝙蝠锥虫，并且尽管与TCI谱系之间存在较大的遗传距离，但TCbat与TCI谱系最为接近。一种针对ITS1 rDNA的基因分型方法能够区分TCbat与已确定的克氏锥虫谱系以及其他裂体锥虫物种。在实验感染的小鼠中，TCbat缺乏毒力且产生的寄生虫血症较低。TCbat分离株在锥蝽中呈现出独特的形态特征和行为。迄今为止，仅在巴西中部和东南部人为环境中的蝙蝠体内发现了TCbat基因型。我们的研究结果表明，克氏锥虫的复杂性比目前已知的更大，并证实蝙蝠是克氏锥虫感染人类的重要储存宿主和潜在来源。
