Abstract
Trypanosoma cruzi, a human protozoan parasite, is the causative agent of Chagas disease. Currently the species is divided into six taxonomic groups. The genome of the CL Brener clone has been estimated to be 106.4–110.7 Mb, and DNA content analyses revealed that it is a diploid hybrid clone. Trypanosoma rangeli is a hemoflagellate that has the same reservoirs and vectors as T. cruzi; however, it is non-pathogenic to vertebrate hosts. The haploid genome of T. rangeli was previously estimated to be 24 Mb. The parasitic strains of T. rangeli are divided into KP1(+) and KP1(−). Thus, the objective of this study was to investigate the DNA content in different strains of T. cruzi and T. rangeli by flow cytometry. All T. cruzi and T. rangeli strains yielded cell cycle profiles with clearly identifiable G1-0 (2n) and G2-M (4n) peaks. T. cruzi and T. rangeli genome sizes were estimated using the clone CL Brener and the Leishmania major CC1 as reference cell lines because their genome sequences have been previously determined. The DNA content of T. cruzi strains ranged from 87,41 to 108,16 Mb, and the DNA content of T. rangeli strains ranged from 63,25 Mb to 68,66 Mb. No differences in DNA content were observed between KP1(+) and KP1(−) T. rangeli strains. Cultures containing mixtures of the epimastigote forms of T. cruzi and T. rangeli strains resulted in cell cycle profiles with distinct G1 peaks for strains of each species. These results demonstrate that DNA content analysis by flow cytometry is a reliable technique for discrimination between T. cruzi and T. rangeli isolated from different hosts.
Highlights
Members of the genus Trypanosoma are protozoan parasites found worldwide and are capable of infecting humans, domestic and wild animals, and insects
A 170-bp fragment was detected from all strains of T. rangeli and a 100-bp fragment was detected from all T. cruzi strains (Fig 1)
We conclude that there is no contamination of T. rangeli cultures with T. cruzi and vice-versa
Summary
Members of the genus Trypanosoma are protozoan parasites found worldwide and are capable of infecting humans, domestic and wild animals, and insects. T. rangeli infection can elicit the production of antibodies that cross-react with T. cruzi antigens. This may lead to the misdiagnosis of Chagas disease leading to a socioepidemiological impact and has not been considered by health authorities [2, 3]. T. cruzi is considered diploid, but some parasitic strains are aneuploids because of a variation in the number of chromosomal bands or distribution of genetic markers, as determined by microsatellite (MS) typing [5, 6]. Flow cytometric analysis using the clone CL Brener as the reference cell line demonstrated a variation in the nuclear genome size between T. cruzi groups, ranging from 80.64 Mb to 153.58 Mb [6, 8]
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