Laboratório de Biologia de Tripanosomatídeos--Instituto Oswaldo Cruz, FIOCRUZ, Av. Brazil 4365, Manguinhos, Rio de Janeiro, Brazil.
Vet Parasitol. 2009 Oct 28;165(1-2):19-24. doi: 10.1016/j.vetpar.2009.07.002. Epub 2009 Jul 10.
Two main genotypes in Trypanosoma cruzi subpopulations can be distinguished by PCR amplification of sequences from the mini-exon gene non-transcribed spacer, respectively, T. cruzi I (TCI) and T. cruzi II (TCII). This technique is also capable of distinguishing a third assemblage of subpopulations that do not fit in these genotypes and that remain known as zymodeme Z3 (Z3). The distribution pattern as well as the mammalian host range of this latter T. cruzi sublineage still remains unclear. Thus, the intention of our study was to increase the information regarding these aspects. The mini-exon analysis of T. cruzi isolates obtained from sylvatic animals in the Amazon Forest, Atlantic Rainforest, Caatinga and Pantanal showed that prevalence of the Z3 subpopulation in nature was low (15 out of 225 isolates, corresponding to 7%). A higher prevalence of Z3 was observed in the Caatinga (15%) and the Pantanal (12%). Infection by Z3 was observed in mammalian hosts included in Carnivora, Chiroptera, Didelphimorphia, Rodentia and Xernathra. The T. cruzi Z3 subpopulation was observed also in mixed infections (33%) with TCI (n=2) and TCII (n=3). These results demonstrate that T. cruzi Z3 displays a wider distribution and host range than formerly understood as it has been demonstrated to be able infect species included in five orders of mammalian host species dispersed through all forest strata of the four Brazilian biomes evaluated.
两种主要的克氏锥虫亚群基因型可通过非转录间隔区迷你外显子基因序列的 PCR 扩增来区分，分别为克氏锥虫 I（TCI）和克氏锥虫 II（TCII）。该技术还能够区分不属于这两种基因型的第三种亚群，这些亚群仍然被称为生物型 Z3（Z3）。这种后者的克氏锥虫亚谱系的分布模式以及哺乳动物宿主范围仍然不清楚。因此，我们的研究旨在增加这些方面的信息。对亚马逊森林、大西洋雨林、卡廷加和潘塔纳尔的野生动物中获得的克氏锥虫分离株进行的迷你外显子分析表明，自然界中 Z3 亚群的流行率较低（225 个分离株中有 15 个，占 7%）。在卡廷加（15%）和潘塔纳尔（12%）中观察到 Z3 的流行率较高。Z3 感染观察到在包括食肉目、翼手目、有袋目、啮齿目和贫齿目在内的哺乳动物宿主中。还观察到 Z3 与 TCI（n=2）和 TCII（n=3）的混合感染（33%）。这些结果表明，与以前的理解相比，克氏锥虫 Z3 的分布范围和宿主范围更广，因为已经证明它能够感染五种哺乳动物宿主目包括的物种，这些物种分散在评估的四个巴西生物区的所有森林层中。
