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Abstract: Internal and geographical clustering within Trypanosoma cruzi I (TcI) has been recently revealed by using Multilocus Microsatellite Typing and sequencing of the Spliced-Leader Intergenic Region (SL-IR). In the present work, 14 isolates and 11 laboratory-cloned stocks obtained from a geographically restricted area in Chaco Province, Argentina, were analyzed by PCR and sequencing of SL-IR. We were able to differentiate 8 different genotypes that clustered into 4 groups. One of these groups was classified within the formerly described haplotype A and another one within the recently described SL-IR group E. Both were phylogenetically well-supported. In contrast, none of the stocks from the Chaco province were grouped within the cluster previously named haplotype D despite the fact that they shared a similar microsatellite motif in the SL-IR. No evidence of recombination or gene conversion within these stocks was found. On the other hand, multiple ambiguous alignments in the microsatellite region of SL-IR, affecting the tree topology and relationships among groups were detected. Finally, since there are multiple copies of the SL-IR, and they are arranged in tandem, we discuss how molecular processes affecting this kind of sequences could mislead phylogenetic inference. [Copyright &y& Elsevier]

Trypanosomes are a group of parasitic flagellates with medical and veterinary importance. Despite many species having been described in this genus, little is known about many of them. Here, we report a genetic and morphological characterization of trypanosomatids isolated from wild mammals from the Argentine Chaco region. Parasites were morphologically and ultrastructurally characterized by light microscopy and transmission electron microscopy. Additionally, 18s rRNA and gGAPDH genes were sequenced and analyzed using maximum likelihood and Bayesian inference. Morphological characterization showed clear characteristics associated with the Trypanosoma genus. The genetic characterization demonstrates that the studied isolates have identical sequences and a pairwise identity of 99% with Trypanosoma lainsoni, which belongs to the clade of lizards and snakes/rodents and marsupials. To date, this species had only been found in the Amazon region. Our finding represents the second report of T. lainsoni and the first record for the Chaco region. Furthermore, we ultrastructurally described for the first time the species. Finally, the host range of T. lainsoni was expanded (Leopardus geoffroyi, Carenivora, Felidae; and Calomys sp., Rodentia, Cricetidae), showing a wide host range for this species. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]