Unidad de Epidemiología Molecular, Instituto de Patología Experimental, CONICET, Universidad Nacional de Salta, Argentina.
Acta Trop. 2012 Sep;123(3):196-201. doi: 10.1016/j.actatropica.2012.05.003. Epub 2012 May 27.
The biological behavior of the different Trypanosoma cruzi strains is still unclear and the importance of exploring the relevance of these differences in natural isolates is of great significance. Herein we describe the biological behavior of four T. cruzi isolates circulating sympatrically in a restricted geographic area in Argentina endemic for Chagas Disease. These isolates were characterized as belonging to the Discrete Typing Units (DTUs) TcI, TcIII, TcV and TcVI as shown by Multilocus Enzyme Electrophoresis and Multilocus Sequence Typing. In order to study the natural behavior of the different isolates and to preserve their natural properties, we developed a vector transmission model that allows their maintenance in the laboratory. The model consisted of serial passages of these parasites between insect vectors and mice. Vector-derived parasite forms were then inoculated in C57BL/6J mice and number of parasite in peripheral blood, serological response and histological damage in acute and chronic phases of the infection were measured. Parasites from DTUs TcI, TcIII and TcVI were detected by direct fresh blood examination, while TcV parasites could only be detected by Polimerase Chain Reaction. No significant difference in the anti-T. cruzi antibody response was found during the chronic phase of infection, except for mice infected with TcV parasites where no antibodies could be detected. Histological sections showed that TcI isolate produced more damage in skeletal muscle while TcVI induced more inflammation in the heart. This work shows differential biological behavior among different parasite isolates obtained from the same cycle of transmission, permitting the opportunity to formulate future hypotheses of clinical and epidemiological importance.
不同的克氏锥虫株的生物学行为仍不清楚，探索这些天然分离株差异的相关性具有重要意义。在此，我们描述了在阿根廷恰加斯病流行的一个受限地理区域内共生的四个 T. cruzi 分离株的生物学行为。这些分离株通过多位点酶电泳和多位点序列分型被鉴定为属于离散型单位（DTU）TcI、TcIII、TcV 和 TcVI。为了研究不同分离株的自然行为并保留其自然特性，我们开发了一种允许它们在实验室中维持的载体传播模型。该模型由这些寄生虫在昆虫载体和小鼠之间的连续传代组成。然后将源自载体的寄生虫形式接种于 C57BL/6J 小鼠中，并测量外周血中的寄生虫数量、急性和慢性感染阶段的血清学反应和组织学损伤。通过直接新鲜血液检查检测到 DTU TcI、TcIII 和 TcVI 的寄生虫，而 TcV 寄生虫只能通过聚合酶链反应检测到。在感染的慢性阶段，除了感染 TcV 寄生虫的小鼠无法检测到抗体外，抗 T. cruzi 抗体反应没有发现显著差异。组织学切片显示 TcI 分离株在骨骼肌中产生更多的损伤，而 TcVI 诱导心脏中更多的炎症。这项工作表明，从同一传播周期获得的不同寄生虫分离株具有不同的生物学行为，为制定未来具有临床和流行病学重要性的假说提供了机会。
