Article

The revised Trypanosoma cruzi subspecific nomenclature: Rationale, epidemiological relevance and research applications

Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Avenida Professor Lineu Prestes 748, 05508-000 São Paulo, SP, Brazil.
Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases (Impact Factor: 3.02). 03/2012; 12(2):240-53. DOI: 10.1016/j.meegid.2011.12.009
Source: PubMed

ABSTRACT

The protozoan Trypanosoma cruzi, its mammalian reservoirs, and vectors have existed in nature for millions of years. The human infection, named Chagas disease, is a major public health problem for Latin America. T. cruzi is genetically highly diverse and the understanding of the population structure of this parasite is critical because of the links to transmission cycles and disease. At present, T. cruzi is partitioned into six discrete typing units (DTUs), TcI-TcVI. Here we focus on the current status of taxonomy-related areas such as population structure, phylogeographical and eco-epidemiological features, and the correlation of DTU with natural and experimental infection. We also summarize methods for DTU genotyping, available for widespread use in endemic areas. For the immediate future multilocus sequence typing is likely to be the gold standard for population studies. We conclude that greater advances in our knowledge on pathogenic and epidemiological features of these parasites are expected in the coming decade through the comparative analysis of the genomes from isolates of various DTUs.

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    • "The interactions between these parasites and vectors are still poorly known, but intrinsic factors of the vector and genotypes of the trypanosomes likely modulate infection in triatomines and consequently interfere with transmission of the disease. TcI, TcII, TcV, and TcVI are the main agents of human Chagas disease in the Americas (Zingales et al., 2012). The elimination of TcIII in most mixed infections in R. prolixus reveals that this DTU is widely distributed in nature (from the southern United States to Argentina) and frequently found in the Amazon region, but the occurrence of TcIII in human infection is rare (Macedo and Segatto, 2010). "
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    ABSTRACT: The specific detection and genetic typing of trypanosomes that infect humans, mammalian reservoirs, and vectors is crucial for diagnosis and epidemiology. We utilized a PCR-RFLP assay that targeted subunit II of cytochrome oxidase and 24Sα-rDNA to simultaneously detect and discriminate six Trypanosoma cruzi discrete typing units (DTUs) and two genetic groups of Trypanosoma rangeli (KP1+/KP1-) in intestinal contents of experimentally infected Rhodnius prolixus. The PCR assays showed that in 23 of 29 (79.4%) mixed infections with the six T. cruzi DTUs and mixed infections with individual DTUs and/or groups KP1+ and KP1-, both parasites were successfully detected. In six mixed infections that involved TcIII, the TcI, TcII, TcV, and TcVI DTUs predominated to the detriment of TcIII, indicating the selection of genetic groups. Interactions between different genetic groups and vectors may lead to genetic selection over TcIII. The elimination of this DTU by the immune system of the vector appears unlikely because TcIII was present in other mixed infections (TcIII/TcIV and TcIII/KP1 + ). Both molecular markers used in this study were sensitive and specific, demonstrating their usefulness in a wide geographical area where distinct genotypes of these two species are sympatric. Although the cellular and molecular mechanisms that are involved in parasite-vector interactions are still poorly understood, our results indicate a dynamic selection toward specific T. cruzi DTUs in R. prolixus during mixed genotype infections.
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    • "Dasypus novemcinctus armadillos and Didelphis opossums (including D. marsupialis, D. aurita and D. albiventris) are the most widespread sylvatic hosts of T. cruzi ; they are usually infected with T. cruzi III (TcIII) and T. cruzi I (TcI), respectively, and display large infectiousness to the vector T. infestans in the Gran Chaco and elsewhere (Alvarado-Otegui et al., 2012; Ceballos et al., 2006; Diosque et al., 2004; Orozco et al., 2013; Yeo et al., 2005). Both TcV and TcVI are prevalent in domestic environments where Triatoma infestans is the primary vector of T. cruzi (Enriquez et al., 2012; Zingales et al., 2012). In the Argentine and Paraguayan Chaco, TcI was isolated from domestic dogs and cats, Didelphis opossums, and more rarely from T. infestans (Cardinal et al., 2008; Diosque et al., 2004; Enriquez et al., 2014; Orozco et al., 2013). "
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    ABSTRACT: Understanding the complex epidemiology of Trypanosoma cruzi transmission cycles requires comparative studies in widely different environments. We assessed the occurrence of T. cruzi infection in sylvatic mammals, their infectiousness to the vector, and parasite genotypes in a protected area of the Argentine Chaco, and compared them with information obtained similarly in a nearby disturbed area. A total of 278 mammals from >23 species in the protected area were diagnosed for T. cruzi infection using xenodiagnosis, kDNA-PCR and nuclear satellite DNA-PCR (SAT) from blood samples. The relative abundance and species composition differed substantially between areas. Didelphis albiventris opossums were less abundant in the protected area; had a significantly lower body mass index, and a stage structure biased toward earlier stages. The capture of armadillos was lower in the protected area. The composite prevalence of T. cruzi infection across host species was significantly lower in the protected area (11.1%) than in the disturbed area (22.1%), and heterogeneous across species groups. The prevalence of infection in Di. albiventris and Thylamys pusilla opossums was significantly lower in the protected area (nil for D. albiventris), whereas infection in sigmodontine rodents was three times higher in the protected area (17.5 vs. 5.7%). Parasite isolates from the two xenodiagnosis-positive mammals (1 Dasypus novemcinctus and 1 Conepatus chinga) were typed as TcIII; both specimens were highly infectious to Triatoma infestans . Fat-tailed opossums, bats and rodents were kDNA-PCR-positive and xenodiagnosis-negative. Desmodus rotundus and Myotis bats were found infected with T. cruzi for the first time in the Gran Chaco.
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    • "It has been hypothesized that the T. cruzi clade was originated from ancestral bat trypanosomes that evolved exclusively in bats or switched into other hosts, giving rise to species that infect terrestrial mammals in the Old and New World (Hamilton et al., 2012b). T. cruzi, the etiological agent of Chagas disease, comprises a complex of genetically heterogeneous isolates distributed into six intraspecific subdivisions known as Discrete Typing Units (DTUs) TcI to TcVI (Zingales et al., 2012), to which a seventh DTU (T. cruzi Tcbat) identified in bats has recently been added (Lima et al., 2015; Marcili et al., 2009; Pinto et al., 2012; Ramírez et al., 2014a). "
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    ABSTRACT: Trans-sialidase (TS) is a polymorphic protein superfamily described in members of the protozoan genus Trypanosoma. Of the eight TS groups recently described, TS group I proteins (some of which have catalytic activity) are present in the distantly related T. brucei and T. cruzi phylogenetic clades, whereas other TS groups have only been described in some species belonging to the T. cruzi clade. In the present study we analyzed the repertoire, distribution and phylogenetic relationships of TS genes among species of the T. cruzi clade based on sequence similarity, multiple sequence alignment and tree-reconstruction approaches using TS sequences obtained with the aid of PCR-based strategies or retrieved from genome databases. We included the following representative isolates of the T. cruzi clade from South America: T. cruzi, T. cruzi Tcbat, T. cruzi marinkellei, T. dionisii, T. rangeli and T. conorhini. The cloned sequences encoded conserved TS protein motifs Asp-box and VTVxNVxLYNR but lacked the FRIP motif (conserved in TS group I). The T. conorhini sequences were the most divergent. The hybridization patterns of TS probes with chromosomal bands confirmed the abundance of these sequences in species in the T. cruzi clade. Divergence and relationship analysis placed most of the TS sequences in the groups defined in T. cruzi. Further examination of members of TS group II, which includes T. cruzi surface glycoproteins implicated in host cell attachment and invasion, showed that sequences of T. cruzi Tcbat grouped with those of T. cruzi genotype TcI. Our analysis indicates that different members of the T. cruzi clade, with different vertebrate hosts, vectors and pathogenicity, share the extensive expansion and sequence diversification of the TS gene family. Altogether, our results are congruent with the evolutionary history of the T. cruzi clade and represent a contribution to the understanding of the molecular evolution and role of TS proteins in trypanosomes.
    Full-text · Article · Dec 2015 · Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases
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