Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, 05508-900 São Paulo, Brazil.
Infect Genet Evol. 2009 Dec;9(6):1265-74. doi: 10.1016/j.meegid.2009.07.003. Epub 2009 Jul 24.
We characterized 28 new isolates of Trypanosoma cruzi IIc (TCIIc) of mammals and triatomines from Northern to Southern Brazil, confirming the widespread distribution of this lineage. Phylogenetic analyses using cytochrome b and SSU rDNA sequences clearly separated TCIIc from TCIIa according to terrestrial and arboreal ecotopes of their preferential mammalian hosts and vectors. TCIIc was more closely related to TCIId/e, followed by TCIIa, and separated by large distances from TCIIb and TCI. Despite being indistinguishable by traditional genotyping and generally being assigned to Z3, we provide evidence that TCIIa from South America and TCIIa from North America correspond to independent lineages that circulate in distinct hosts and ecological niches. Armadillos, terrestrial didelphids and rodents, and domestic dogs were found infected by TCIIc in Brazil. We believe that, in Brazil, this is the first description of TCIIc from rodents and domestic dogs. Terrestrial triatomines of genera Panstrongylus and Triatoma were confirmed as vectors of TCIIc. Together, habitat, mammalian host and vector association corroborated the link between TCIIc and terrestrial transmission cycles/ecological niches. Analysis of ITS1 rDNA sequences disclosed clusters of TCIIc isolates in accordance with their geographic origin, independent of their host species.
我们对来自巴西北部到南部的 28 株新型克氏锥虫 IIc（TCIIc）哺乳动物和三锥虫进行了特征描述，证实了该谱系的广泛分布。使用细胞色素 b 和 SSU rDNA 序列进行的系统发育分析，根据其偏爱哺乳动物宿主和媒介的陆地和树栖生态位，将 TCIIc 与 TCIIa 明显区分开来。TCIIc 与 TCIId/e 的亲缘关系更密切，其次是 TCIIa，与 TCIIb 和 TCI 相隔很远。尽管传统的基因分型无法区分，但通常被归类为 Z3，我们提供的证据表明，来自南美洲的 TCIIa 和来自北美的 TCIIa 对应于独立的谱系，它们在不同的宿主和生态位中循环。在巴西，发现犰狳、陆地袋狸和啮齿动物以及家养狗感染了 TCIIc。我们认为，这是巴西首次从啮齿动物和家养狗中描述 TCIIc。潘氏属和三锥属的陆地三锥虫被确认为 TCIIc 的媒介。栖息地、哺乳动物宿主和媒介的关联共同证实了 TCIIc 与陆地传播周期/生态位之间的联系。ITS1 rDNA 序列分析显示，TCIIc 分离株的聚类与其地理起源一致，与宿主种类无关。
