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Genotypic variation among lineages of Trypanosoma cruzi and its geographic aspects |
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| Authors: | Higo Hiroo Miura Sachio Horio Masahiro Mimori Tatsuyuki Hamano Shinjiro Agatsuma Takeshi Yanagi Tetsuo Cruz-Reyes Arejandro Uyema Norma Rojas de Arias A Matta Vivian Akahane Hiroshige Hirayama Kenji Takeuchi Tsutomu Tada Isao Himeno Kunisuke |
| Institution: | a Department of Parasitology, Graduate School of Medical Sciences, Kyushu University, Maidashi 3-1-1, Higashiku, Fukuoka 812-8582, Japan b Department of Tropical Medicine and Parasitology, School of Medicine, Keio University, Keio, Japan c Department of Parasitology and Tropical Public Health, School of Medicine, University of Occupation and Environment Health, Japan d Department of Tumor Genetic Biology, School of Medicine, Kumamoto University, Japan e Department of Environmental Health Science, Kochi Medical School, Japan f Department of Protozoology, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan g Instituto de Biologia, Universidad Nacional Autonoma de Mexico, Mexico h Laboratorio de Microbiologia, Facultad de Mdicina, Universidad San Martin de Porres, Peru i Department of Tropical Medicine, Institute de Investigaciones en Ciencias de la Salud, Asuncion, Paraguay j Facultad de Ciencias Quimicas y Farmacia, Universidad Nacional de San Carlos, Guatemala k Department of Parasitology, School of Medicine, Fukuoka University, Japan l Department of Molecular Immunogenetics, Institute of Tropical Medicine, Nagasaki University, Japan |
| Abstract: | Isozyme analysis with 18 enzyme loci was conducted on 146 isolates of Trypanosoma cruzi from Mexico, Guatemala, Colombia, Ecuador, Peru, Brazil, Bolivia, Paraguay and Chile. Forty-four different MLGs (groups of isolates with identical multilocus genotypes) were identified and a phylogeny was constructed. The phylogenetic tree consisted of two main groups (T. cruzi I, T. cruzi II), and the latter was further divided into two subgroups (T. cruzi IIa, T. cruzi IIb–e). Evidence of hybridization between different MLGs of T. cruzi II was found, which means that genetic exchanges seem to have occurred in South American T. cruzi. On the other hand, the persistence of characteristic T. cruzi I and T. cruzi II isozyme patterns in single small villages in Bolivia and Guatemala suggested that genetic exchange is very rare between major lineages. A significant difference in genetic diversity was shown between T. cruzi I and T. cruzi II from several indices of population genetics. Two possibilities could explain this genetic variation in the population: differences in evolutionary history and/or different tendencies to exchange genetic material. Broad-scale geographic distributions of T. cruzi I and T. cruzi IIb–e were different; T. cruzi I occurred in Central America and south to Bolivia and Brazil, while T. cruzi IIb–e occurred in the central and southern areas of South America, overlapping with T. cruzi I in Brazil and Bolivia. |
| Keywords: | Trypanosoma cruzi Chagas' disease Isozyme Phylogeny Genetic exchange Genetic variation Pathogenicity |
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