1
|
Zingales B, Macedo AM. Fifteen Years after the Definition of Trypanosoma cruzi DTUs: What Have We Learned? Life (Basel) 2023; 13:2339. [PMID: 38137940 PMCID: PMC10744745 DOI: 10.3390/life13122339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 12/04/2023] [Accepted: 12/06/2023] [Indexed: 12/24/2023] Open
Abstract
Trypanosoma cruzi, the protozoan causative of Chagas disease (ChD), exhibits striking genetic and phenotypic intraspecific diversity, along with ecoepidemiological complexity. Human-pathogen interactions lead to distinct clinical presentations of ChD. In 2009, an international consensus classified T. cruzi strains into six discrete typing units (DTUs), TcI to TcVI, later including TcBat, and proposed reproducible genotyping schemes for DTU identification. This article aims to review the impact of classifying T. cruzi strains into DTUs on our understanding of biological, ecoepidemiological, and pathogenic aspects of T. cruzi. We will explore the likely origin of DTUs and the intrinsic characteristics of each group of strains concerning genome organization, genomics, and susceptibility to drugs used in ChD treatment. We will also provide an overview of the association of DTUs with mammalian reservoirs, and summarize the geographic distribution, and the clinical implications, of prevalent specific DTUs in ChD patients. Throughout this review, we will emphasize the crucial roles of both parasite and human genetics in defining ChD pathogenesis and chemotherapy outcome.
Collapse
Affiliation(s)
- Bianca Zingales
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo 05508-900, São Paulo, Brazil
| | - Andréa M. Macedo
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil;
| |
Collapse
|
2
|
In Silico Identification of New Targets for Diagnosis, Vaccine, and Drug Candidates against Trypanosoma cruzi. DISEASE MARKERS 2021; 2020:9130719. [PMID: 33488847 PMCID: PMC7787821 DOI: 10.1155/2020/9130719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 03/23/2020] [Accepted: 11/24/2020] [Indexed: 11/17/2022]
Abstract
Chagas disease is a neglected tropical disease caused by the parasite Trypanosoma cruzi. Despite the efforts and distinct methodologies, the search of antigens for diagnosis, vaccine, and drug targets for the disease is still needed. The present study is aimed at identifying possible antigens that could be used for diagnosis, vaccine, and drugs targets against T. cruzi using reverse vaccinology and molecular docking. The genomes of 28 T. cruzi strains available in GenBank (NCBI) were used to obtain the genomic core. Then, subtractive genomics was carried out to identify nonhomologous genes to the host in the core. A total of 2630 conserved proteins in 28 strains of T. cruzi were predicted using OrthoFinder and Diamond software, in which 515 showed no homology to the human host. These proteins were evaluated for their subcellular localization, from which 214 are cytoplasmic and 117 are secreted or present in the plasma membrane. To identify the antigens for diagnosis and vaccine targets, we used the VaxiJen software, and 14 nonhomologous proteins were selected showing high binding efficiency with MHC I and MHC II with potential for in vitro and in vivo tests. When these 14 nonhomologous molecules were compared against other trypanosomatids, it was found that the retrotransposon hot spot (RHS) protein is specific only for T. cruzi parasite suggesting that it could be used for Chagas diagnosis. Such 14 proteins were analyzed using the IEDB software to predict their epitopes in both B and T lymphocytes. Furthermore, molecular docking analysis was performed using the software MHOLline. As a result, we identified 6 possible T. cruzi drug targets that could interact with 4 compounds already known as antiparasitic activities. These 14 protein targets, along with 6 potential drug candidates, can be further validated in future studies, in vivo, regarding Chagas disease.
Collapse
|
3
|
Bradwell KR, Koparde VN, Matveyev AV, Serrano MG, Alves JMP, Parikh H, Huang B, Lee V, Espinosa-Alvarez O, Ortiz PA, Costa-Martins AG, Teixeira MMG, Buck GA. Genomic comparison of Trypanosoma conorhini and Trypanosoma rangeli to Trypanosoma cruzi strains of high and low virulence. BMC Genomics 2018; 19:770. [PMID: 30355302 PMCID: PMC6201504 DOI: 10.1186/s12864-018-5112-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 09/25/2018] [Indexed: 01/09/2023] Open
Abstract
Background Trypanosoma conorhini and Trypanosoma rangeli, like Trypanosoma cruzi, are kinetoplastid protist parasites of mammals displaying divergent hosts, geographic ranges and lifestyles. Largely nonpathogenic T. rangeli and T. conorhini represent clades that are phylogenetically closely related to the T. cruzi and T. cruzi-like taxa and provide insights into the evolution of pathogenicity in those parasites. T. rangeli, like T. cruzi is endemic in many Latin American countries, whereas T. conorhini is tropicopolitan. T. rangeli and T. conorhini are exclusively extracellular, while T. cruzi has an intracellular stage in the mammalian host. Results Here we provide the first comprehensive sequence analysis of T. rangeli AM80 and T. conorhini 025E, and provide a comparison of their genomes to those of T. cruzi G and T. cruzi CL, respectively members of T. cruzi lineages TcI and TcVI. We report de novo assembled genome sequences of the low-virulent T. cruzi G, T. rangeli AM80, and T. conorhini 025E ranging from ~ 21–25 Mbp, with ~ 10,000 to 13,000 genes, and for the highly virulent and hybrid T. cruzi CL we present a ~ 65 Mbp in-house assembled haplotyped genome with ~ 12,500 genes per haplotype. Single copy orthologs of the two T. cruzi strains exhibited ~ 97% amino acid identity, and ~ 78% identity to proteins of T. rangeli or T. conorhini. Proteins of the latter two organisms exhibited ~ 84% identity. T. cruzi CL exhibited the highest heterozygosity. T. rangeli and T. conorhini displayed greater metabolic capabilities for utilization of complex carbohydrates, and contained fewer retrotransposons and multigene family copies, i.e. trans-sialidases, mucins, DGF-1, and MASP, compared to T. cruzi. Conclusions Our analyses of the T. rangeli and T. conorhini genomes closely reflected their phylogenetic proximity to the T. cruzi clade, and were largely consistent with their divergent life cycles. Our results provide a greater context for understanding the life cycles, host range expansion, immunity evasion, and pathogenesis of these trypanosomatids. Electronic supplementary material The online version of this article (10.1186/s12864-018-5112-0) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Katie R Bradwell
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA, USA.,Present address: Institute for Genome Sciences, University of Maryland, Baltimore, MD, USA
| | - Vishal N Koparde
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA, USA
| | - Andrey V Matveyev
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA, USA.,Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA, USA
| | - Myrna G Serrano
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA, USA.,Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA, USA
| | - João M P Alves
- Department of Parasitology, ICB, University of São Paulo, São Paulo, SP, Brazil
| | - Hardik Parikh
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA, USA.,Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA, USA
| | - Bernice Huang
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA, USA.,Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA, USA
| | - Vladimir Lee
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA, USA
| | | | - Paola A Ortiz
- Department of Parasitology, ICB, University of São Paulo, São Paulo, SP, Brazil
| | | | - Marta M G Teixeira
- Department of Parasitology, ICB, University of São Paulo, São Paulo, SP, Brazil
| | - Gregory A Buck
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA, USA. .,Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA, USA.
| |
Collapse
|
4
|
Zingales B. Trypanosoma cruzi genetic diversity: Something new for something known about Chagas disease manifestations, serodiagnosis and drug sensitivity. Acta Trop 2018; 184:38-52. [PMID: 28941731 DOI: 10.1016/j.actatropica.2017.09.017] [Citation(s) in RCA: 235] [Impact Index Per Article: 39.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 08/18/2017] [Accepted: 09/18/2017] [Indexed: 11/27/2022]
Abstract
The genetic diversity of Trypanosoma cruzi, the protozoan agent of Chagas disease, is widely recognized. At present, T. cruzi is partitioned into seven discrete typing units (DTUs), TcI-TcVI and Tcbat. This article reviews the present knowledge on the parasite population structure, the evolutionary relationships among DTUs and their distinct, but not exclusive ecological and epidemiological associations. Different models for the origin of hybrid DTUs are examined, which agree that genetic exchange among T. cruzi populations is frequent and has contributed to the present parasite population structure. The geographic distribution of the prevalent DTUs in humans from the southern United States to Argentina is here presented and the circumstantial evidence of a possible association between T. cruzi genotype and Chagas disease manifestations is discussed. The available information suggests that parasite strains detected in patients, regardless of the clinical presentation, reflect the principal DTU circulating in the domestic transmission cycles of a particular region. In contrast, in several orally transmitted outbreaks, sylvatic strains are implicated. As a consequence of the genotypic and phenotypic differences of T. cruzi strains and the differential geographic distribution of DTUs in humans, regional variations in the sensitivity of the serological tests are verified. The natural resistance to benznidazole and nifurtimox, verified in vivo and in vitro for some parasite stocks, is not associated with any particular DTU, and does not explain the marked difference in the anti-parasitic efficacy of both drugs in the acute and chronic phases of Chagas disease. Throughout this review, it is emphasized that the interplay between parasite and host genetics should have an important role in the definition of Chagas disease pathogenesis, anti-T. cruzi immune response and chemotherapy outcome and should be considered in future investigations.
Collapse
Affiliation(s)
- Bianca Zingales
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Avenida Professor Lineu Prestes 748, 05508-000 São Paulo, SP, Brazil.
| |
Collapse
|
5
|
Barnabé C, Mobarec HI, Jurado MR, Cortez JA, Brenière SF. Reconsideration of the seven discrete typing units within the species Trypanosoma cruzi , a new proposal of three reliable mitochondrial clades. INFECTION GENETICS AND EVOLUTION 2016; 39:176-186. [DOI: 10.1016/j.meegid.2016.01.029] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 01/29/2016] [Accepted: 01/30/2016] [Indexed: 10/22/2022]
|
6
|
Reis-Cunha JL, Mendes TADO, de Almeida Lourdes R, Ribeiro DRDS, Machado-de-Avila RA, de Oliveira Tavares M, Lemos DS, Câmara ACJ, Olórtegui CC, de Lana M, da Cunha Galvão LM, Fujiwara RT, Bartholomeu DC. Genome-wide screening and identification of new Trypanosoma cruzi antigens with potential application for chronic Chagas disease diagnosis. PLoS One 2014; 9:e106304. [PMID: 25225853 PMCID: PMC4165580 DOI: 10.1371/journal.pone.0106304] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 08/05/2014] [Indexed: 12/21/2022] Open
Abstract
The protozoan Trypanosoma cruzi is the etiologic agent of Chagas disease, an infection that afflicts approximately 8 million people in Latin America. Diagnosis of chronic Chagas disease is currently based on serological tests because this condition is usually characterized by high anti-T. cruzi IgG titers and low parasitemia. The antigens used in these assays may have low specificity due to cross reactivity with antigens from related parasite infections, such as leishmaniasis, and low sensitivity caused by the high polymorphism among T. cruzi strains. Therefore, the identification of new T. cruzi-specific antigens that are conserved among the various parasite discrete typing units (DTUs) is still required. In the present study, we have explored the hybrid nature of the T. cruzi CL Brener strain using a broad genome screening approach to select new T. cruzi antigens that are conserved among the different parasite DTUs and that are absent in other trypanosomatid species. Peptide arrays containing the conserved antigens with the highest epitope prediction scores were synthesized, and the reactivity of the peptides were tested by immunoblot using sera from C57BL/6 mice chronically infected with T. cruzi strains from the TcI, TcII or TcVI DTU. The two T. cruzi proteins that contained the most promising peptides were expressed as recombinant proteins and tested in ELISA experiments with sera from chagasic patients with distinct clinical manifestations: those infected with T. cruzi from different DTUs and those with cutaneous or visceral leishmaniasis. These proteins, named rTc_11623.20 and rTc_N_10421.310, exhibited 94.83 and 89.66% sensitivity, 98.2 and 94.6% specificity, respectively, and a pool of these 2 proteins exhibited 96.55% sensitivity and 98.18% specificity. This work led to the identification of two new antigens with great potential application in the diagnosis of chronic Chagas disease.
Collapse
Affiliation(s)
- João Luís Reis-Cunha
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | - Rodrigo de Almeida Lourdes
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | - Ricardo Andrez Machado-de-Avila
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Maykon de Oliveira Tavares
- Departamento de Análises Clínicas, Escola de Farmácia, Universidade Federal de Ouro Preto, Ouro Preto, Brazil
| | - Denise Silveira Lemos
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | - Carlos Chavez Olórtegui
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Marta de Lana
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | - Ricardo Toshio Fujiwara
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | |
Collapse
|
7
|
DNA repair pathways in trypanosomatids: from DNA repair to drug resistance. Microbiol Mol Biol Rev 2014; 78:40-73. [PMID: 24600040 DOI: 10.1128/mmbr.00045-13] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
All living organisms are continuously faced with endogenous or exogenous stress conditions affecting genome stability. DNA repair pathways act as a defense mechanism, which is essential to maintain DNA integrity. There is much to learn about the regulation and functions of these mechanisms, not only in human cells but also equally in divergent organisms. In trypanosomatids, DNA repair pathways protect the genome against mutations but also act as an adaptive mechanism to promote drug resistance. In this review, we scrutinize the molecular mechanisms and DNA repair pathways which are conserved in trypanosomatids. The recent advances made by the genome consortiums reveal the complete genomic sequences of several pathogens. Therefore, using bioinformatics and genomic sequences, we analyze the conservation of DNA repair proteins and their key protein motifs in trypanosomatids. We thus present a comprehensive view of DNA repair processes in trypanosomatids at the crossroads of DNA repair and drug resistance.
Collapse
|
8
|
Mattos EC, Tonelli RR, Colli W, Alves MJM. The Gp85 surface glycoproteins from Trypanosoma cruzi. Subcell Biochem 2014; 74:151-180. [PMID: 24264245 DOI: 10.1007/978-94-007-7305-9_7] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Trypanosoma cruzi strains show distinctive characteristics as genetic polymorphism and infectivity. Large repertoires of molecules, such as the Gp85 glycoproteins, members of the Gp85/Trans-sialidase superfamily, as well as multiple signaling pathways, are associated with invasion of mammalian cells by the parasite. Due to the large number of expressed members, encoded by more than 700 genes, the research focused on this superfamily conserved sequences is discussed. Binding sites to laminin have been identified at the N-terminus of the Gp85 molecules. Interestingly, the T. cruzi protein phosphorylation profile is changed upon parasite binding to laminin (or fibronectin), particularly the cytoskeletal proteins such as those from the paraflagellar rod and the tubulins, which are both markedly dephosphorylated. Detailed analysis of the signaling cascades triggered upon T. cruzi binding to extracellular matrix (ECM) proteins revealed the involvement of the MAPK/ERK pathway in this event. At the C-terminus, the conserved FLY sequence is a cytokeratin-binding domain and is involved in augmented host cell invasion in vitro and high levels of parasitemia in vivo. FLY, which is associated to tissue tropism and preferentially binds to the heart vasculature may somehow be correlated with the severe cardiac form, an important clinical manifestation of chronic Chagas' disease.
Collapse
Affiliation(s)
- Eliciane C Mattos
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, 05508-900, Cidade Universitária, São Paulo, Brazil
| | | | | | | |
Collapse
|
9
|
Baptista RDP, D'Ávila DA, Segatto M, do Valle ÍF, Franco GR, Valadares HMS, Gontijo ED, Galvão LMDC, Pena SDJ, Chiari E, Machado CR, Macedo AM. Evidence of substantial recombination among Trypanosoma cruzi II strains from Minas Gerais. INFECTION GENETICS AND EVOLUTION 2013; 22:183-91. [PMID: 24296011 DOI: 10.1016/j.meegid.2013.11.021] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 11/22/2013] [Accepted: 11/23/2013] [Indexed: 01/06/2023]
Abstract
Due to the scarcity of evidence of sexuality in Trypanosoma cruzi, the causative agent of Chagas disease, it has been general accepted that the parasite reproduction is essentially clonal with infrequent genetic recombination. This assumption is mainly supported by indirect evidence, such as Hardy-Weinberg imbalances, linkage disequilibrium and a strong correlation between independent sets of genetic markers of T. cruzi populations. However, because the analyzed populations are usually isolated from different geographic regions, the possibility of population substructuring as generating these genetic marker imbalances cannot be eliminated. To investigate this possibility, we firstly compared the allele frequencies and haplotype networks using seven different polymorphic loci (two from mitochondrial and five from different nuclear chromosomes) in two groups of TcII strains: one including isolates obtained from different regions in Latin America and the other including isolates obtained only from patients of the Minas Gerais State in Brazil. Our hypothesis was that if the population structure is essentially clonal, Hardy-Weinberg disequilibrium and a sharp association between the clusters generated by analyzing independent markers should be observed in both strain groups, independent of the geographic origin of the samples. The results demonstrated that the number of microsatellite loci in linkage disequilibrium decreased from 4 to 1 when only strains from Minas Gerais were analyzed. Moreover, we did not observed any correlation between the clusters when analyzing the nuclear and mitochondrial loci, suggesting independent inheritance of these markers among the Minas Gerais strains. Besides, using a second subset of five physically linked microsatellite loci and the Minas Gerais strains, we could also demonstrate evidence of homologous recombination roughly proportional to the relative distance among them. Taken together, our results do not support a clonal population structure for T. cruzi, particularly in TcII, which coexists in the same geographical area, suggesting that genetic exchanges among these strains may occur more frequently than initially expected.
Collapse
Affiliation(s)
- Rodrigo de Paula Baptista
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Daniella Alchaar D'Ávila
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Marcela Segatto
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Ítalo Faria do Valle
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Glória Regina Franco
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | | | - Eliane Dias Gontijo
- Departamento de Medicina Preventiva e Social, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Lúcia Maria da Cunha Galvão
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Centro de Ciências da Saúde, Universidade Federal do Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
| | - Sérgio Danilo Junho Pena
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Egler Chiari
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Carlos Renato Machado
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
| | - Andréa Mara Macedo
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
| |
Collapse
|
10
|
Barnabe C, Buitrago R, Bremond P, Aliaga C, Salas R, Vidaurre P, Herrera C, Cerqueira F, Bosseno MF, Waleckx E, Breniere SF. Putative panmixia in restricted populations of Trypanosoma cruzi isolated from wild Triatoma infestans in Bolivia. PLoS One 2013; 8:e82269. [PMID: 24312410 PMCID: PMC3843716 DOI: 10.1371/journal.pone.0082269] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 10/29/2013] [Indexed: 01/26/2023] Open
Abstract
Trypanosoma cruzi, the causative agent of Chagas disease, is subdivided into six discrete typing units (DTUs; TcI-TcVI) of which TcI is ubiquitous and genetically highly variable. While clonality is the dominant mode of propagation, recombinant events play a significant evolutive role. Recently, foci of wild Triatoma infestans have been described in Bolivia, mainly infected by TcI. Hence, for the first time, we evaluated the level of genetic exchange within TcI natural potentially panmictic populations (single DTU, host, area and sampling time). Seventy-nine TcI stocks from wild T. infestans, belonging to six populations were characterized at eight microsatellite loci. For each population, Hardy-Weinberg equilibrium (HWE), linkage disequilibrium (LD), and presence of repeated multilocus genotypes (MLG) were analyzed by using a total of seven statistics, to test the null hypothesis of panmixia (H0). For three populations, none of the seven statistics allowed to rejecting H0; for another one the low size did not allow us to conclude, and for the two others the tests have given contradictory results. Interestingly, apparent panmixia was only observed in very restricted areas, and was not observed when grouping populations distant of only two kilometers or more. Nevertheless it is worth stressing that for the statistic tests of "HWE", in order to minimize the type I error (i. e. incorrect rejection of a true H0), we used the Bonferroni correction (BC) known to considerably increase the type II error ( i. e. failure to reject a false H0). For the other tests (LD and MLG), we did not use BC and the risk of type II error in these cases was acceptable. Thus, these results should be considered as a good indicator of the existence of panmixia in wild environment but this must be confirmed on larger samples to reduce the risk of type II error.
Collapse
Affiliation(s)
- Christian Barnabe
- MIVEGEC (Université de Montpellier 1 et 2 - CNRS 5290 - IRD 224), Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, Institut de recherche pour le développement (IRD), Representation in Bolivia, La Paz, Bolivia
- Instituto Nacional de Laboratorios de Salud (INLASA), Department of Entomology, La Paz, Bolivia
| | - Rosio Buitrago
- MIVEGEC (Université de Montpellier 1 et 2 - CNRS 5290 - IRD 224), Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, Institut de recherche pour le développement (IRD), Representation in Bolivia, La Paz, Bolivia
- Instituto Nacional de Laboratorios de Salud (INLASA), Department of Entomology, La Paz, Bolivia
| | - Philippe Bremond
- MIVEGEC (Université de Montpellier 1 et 2 - CNRS 5290 - IRD 224), Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, Institut de recherche pour le développement (IRD), Representation in Bolivia, La Paz, Bolivia
| | - Claudia Aliaga
- MIVEGEC (Université de Montpellier 1 et 2 - CNRS 5290 - IRD 224), Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, Institut de recherche pour le développement (IRD), Representation in Bolivia, La Paz, Bolivia
- Instituto Nacional de Laboratorios de Salud (INLASA), Department of Entomology, La Paz, Bolivia
| | - Renata Salas
- MIVEGEC (Université de Montpellier 1 et 2 - CNRS 5290 - IRD 224), Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, Institut de recherche pour le développement (IRD), Representation in Bolivia, La Paz, Bolivia
- Instituto Nacional de Laboratorios de Salud (INLASA), Department of Entomology, La Paz, Bolivia
| | - Pablo Vidaurre
- Servicio Departamental de Salud (SEDES) of La Paz, La Paz, Bolivia
| | - Claudia Herrera
- Department of Tropical Medicine, Tulane University, School of Public Health and Tropical Medicine, New Orleans, Louisiana, United States of America
| | - Frédérique Cerqueira
- Plateforme Génomique Environnementale du Labex Centre "Méditerranéen Environnement Biodiversité", Séquençage – Génotypage, Université Montpellier 2, Montpellier, France
| | - Marie-France Bosseno
- MIVEGEC (Université de Montpellier 1 et 2 - CNRS 5290 - IRD 224), Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, Institut de recherche pour le développement (IRD), Representation in Bolivia, La Paz, Bolivia
- Instituto Nacional de Laboratorios de Salud (INLASA), Department of Entomology, La Paz, Bolivia
| | - Etienne Waleckx
- MIVEGEC (Université de Montpellier 1 et 2 - CNRS 5290 - IRD 224), Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, Institut de recherche pour le développement (IRD), Representation in Bolivia, La Paz, Bolivia
- Instituto Nacional de Laboratorios de Salud (INLASA), Department of Entomology, La Paz, Bolivia
| | - Simone Frédérique Breniere
- MIVEGEC (Université de Montpellier 1 et 2 - CNRS 5290 - IRD 224), Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, Institut de recherche pour le développement (IRD), Representation in Bolivia, La Paz, Bolivia
- Instituto Nacional de Laboratorios de Salud (INLASA), Department of Entomology, La Paz, Bolivia
| |
Collapse
|
11
|
Zingales B, Miles MA, Campbell DA, Tibayrenc M, Macedo AM, Teixeira MMG, Schijman AG, Llewellyn MS, Lages-Silva E, Machado CR, Andrade SG, Sturm NR. The revised Trypanosoma cruzi subspecific nomenclature: rationale, epidemiological relevance and research applications. INFECTION GENETICS AND EVOLUTION 2011; 12:240-53. [PMID: 22226704 DOI: 10.1016/j.meegid.2011.12.009] [Citation(s) in RCA: 602] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 12/16/2011] [Indexed: 10/14/2022]
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.
Collapse
Affiliation(s)
- Bianca Zingales
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Avenida Professor Lineu Prestes 748, 05508-000 São Paulo, SP, Brazil.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Analyses of 32 loci clarify phylogenetic relationships among Trypanosoma cruzi lineages and support a single hybridization prior to human contact. PLoS Negl Trop Dis 2011; 5:e1272. [PMID: 21829751 PMCID: PMC3149036 DOI: 10.1371/journal.pntd.0001272] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Accepted: 06/22/2011] [Indexed: 01/23/2023] Open
Abstract
Background The genetic diversity of Trypanosoma cruzi, the etiological agent of Chagas disease, has been traditionally divided in two major groups, T. cruzi I and II, corresponding to discrete typing units TcI and TcII-VI under a recently proposed nomenclature. The two major groups of T. cruzi seem to differ in important biological characteristics, and are thus thought to represent a natural division relevant for epidemiological studies and development of prophylaxis. To understand the potential connection between the different manifestations of Chagas disease and variability of T. cruzi strains, it is essential to have a correct reconstruction of the evolutionary history of T. cruzi. Methodology/Principal Findings Nucleotide sequences from 32 unlinked loci (>26 Kilobases of aligned sequence) were used to reconstruct the evolutionary history of strains representing the known genetic variability of T. cruzi. Thorough phylogenetic analyses show that the original classification of T. cruzi in two major lineages does not reflect its evolutionary history and that there is only strong evidence for one major and recent hybridization event in the history of this species. Furthermore, estimates of divergence times using Bayesian methods show that current extant lineages of T. cruzi diverged very recently, within the last 3 million years, and that the major hybridization event leading to hybrid lineages TcV and TcVI occurred less than 1 million years ago, well before the contact of T. cruzi with humans in South America. Conclusions/Significance The described phylogenetic relationships among the six major genetic subdivisions of T. cruzi should serve as guidelines for targeted epidemiological and prophylaxis studies. We suggest that it is important to reconsider conclusions from previous studies that have attempted to uncover important biological differences between the two originally defined major lineages of T. cruzi especially if those conclusions were obtained from single or few strains. Trypanosoma cruzi is the protozoan parasite that causes Chagas disease, a major health problem in Latin America. The genetic diversity of this parasite has been traditionally divided in two major groups: T. cruzi I and II, which can be further divided in six major genetic subdivisions (subgroups TcI-TcVI). T. cruzi I and II seem to differ in important biological characteristics, and are thought to represent a natural division relevant for epidemiological studies and development of prophylaxis. Having a correct reconstruction of the evolutionary history of T. cruzi is essential for understanding the potential connection between the genetic and phenotypic variability of T. cruzi with the different manifestations of Chagas disease. Here we present results from a comprehensive phylogenetic analysis of T. cruzi using more than 26 Kb of aligned sequence data. We show strong evidence that T. cruzi II (TcII-VI) is not a natural evolutionary group but a paraphyletic lineage and that all major lineages of T. cruzi evolved recently (<3 million years ago [mya]). Furthermore, the sequence data is consistent with one major hybridization event having occurred in this species recently (< 1 mya) but well before T. cruzi entered in contact with humans in South America.
Collapse
|
13
|
The Trypanosoma cruzi genome; conserved core genes and extremely variable surface molecule families. Res Microbiol 2011; 162:619-25. [PMID: 21624458 DOI: 10.1016/j.resmic.2011.05.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2011] [Accepted: 04/14/2011] [Indexed: 11/21/2022]
Abstract
The protozoan parasite Trypanosoma cruzi is an important but neglected pathogen that causes chagas disease, which affects millions of people, mainly in latin America. The population structure and epidemiology of the parasite are complex, with much variability among strains. The genome sequence of a reference strain, CL Brener, was published in 2005, and the availability of this sequence has both revealed the complexity of the parasite genome and greatly facilitated research into parasite biology and pathogenesis, by making the sequences of more than 8000 core genes available. The T. cruzi genome is highly repetitive, which has resulted in inaccuracies in the genome sequence, and attempts have been made to provide a deeper analysis of repeated genes as a complement to the genome sequence. The genome was found to be organized in stable core regions containing housekeeping and other genes, surrounded by highly repetitive, often sub-telomeric highly variable regions containing multiple members of large families of surface molecule genes. Comparative sequencing of T. cruzi strains has been initiated and the results show that the core gene content of the parasite is highly conserved, but that much sequence variability, 3-4% difference at the DNA level on average between strains in coding regions, is present. The additional genomes will improve the understanding of parasite biology and epidemiology.
Collapse
|
14
|
Passos-Silva DG, Rajão MA, Nascimento de Aguiar PH, Vieira-da-Rocha JP, Machado CR, Furtado C. Overview of DNA Repair in Trypanosoma cruzi, Trypanosoma brucei, and Leishmania major. J Nucleic Acids 2010; 2010:840768. [PMID: 20976268 PMCID: PMC2952945 DOI: 10.4061/2010/840768] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Revised: 07/29/2010] [Accepted: 08/25/2010] [Indexed: 12/18/2022] Open
Abstract
A wide variety of DNA lesions arise due to environmental agents, normal cellular metabolism, or intrinsic weaknesses in the chemical bonds of DNA. Diverse cellular mechanisms have evolved to maintain genome stability, including mechanisms to repair damaged DNA, to avoid the incorporation of modified nucleotides, and to tolerate lesions (translesion synthesis). Studies of the mechanisms related to DNA metabolism in trypanosomatids have been very limited. Together with recent experimental studies, the genome sequencing of Trypanosoma brucei, Trypanosoma cruzi, and Leishmania major, three related pathogens with different life cycles and disease pathology, has revealed interesting features of the DNA repair mechanism in these protozoan parasites, which will be reviewed here.
Collapse
Affiliation(s)
- Danielle Gomes Passos-Silva
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Pampulha, 31270-901 Belo Horizonte, MG, Brazil
| | | | | | | | | | | |
Collapse
|
15
|
Alternative lifestyles: the population structure of Trypanosoma cruzi. Acta Trop 2010; 115:35-43. [PMID: 19695212 DOI: 10.1016/j.actatropica.2009.08.018] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2009] [Revised: 07/22/2009] [Accepted: 08/13/2009] [Indexed: 11/23/2022]
Abstract
The genetic palette from which the spectrum of variability in Trypanosoma cruzi has been drawn is astonishingly limited. In this review we address the roots of this unusual pedigree and the usefulness of various taxonomic markers in relation to the manifestation of clinical disease and the geographic distribution of the parasite. The circumstances leading to the population structure of the extant strains were dictated by the unusual and apparently exceedingly rare mode of genetic exchange employed in this species, that being the non-meiotic fusion of two diploid cells. Two-hybridization events have been postulated in the whole of the T. cruzi pedigree, the first of which yielded the four predominant nuclear genotypes. Hybridization may be a common occurrence among closely related strains of T. cruzi, but either infrequent or inefficient when two diverse strains attempt the process. Two of the genotypes define the parental lineages, while the other two are mosaics of the parental contributions distinguished from one another by polymorphisms accumulated after the separation of a common, homozygous hybrid progeny line. The greatest genetic complexity is seen in the result of the second fusion event between one of the original parental strains and a progeny strain. The second generation of progeny reveals the proximal consequences of fusion, maintaining widespread nuclear heterozygosity and the first examples of recombination between the genotypes involved in the second hybridization. If the genesis of the heterozygous progeny follows the same path as their predecessors, these lines will move toward homozygosity after having had the opportunity for recombination. Thus, the total number of alleles may increase to five in another few million years.
Collapse
|
16
|
Modelling the Transmission of Trypanosoma cruzi: The Need for an Integrated Genetic Epidemiological and Population Genomics Approach. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 673:200-11. [DOI: 10.1007/978-1-4419-6064-1_14] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/19/2023]
|
17
|
Subileau M, Barnabé C, Douzery E, Diosque P, Tibayrenc M. Trypanosoma cruzi: New insights on ecophylogeny and hybridization by multigene sequencing of three nuclear and one maxicircle genes. Exp Parasitol 2009; 122:328-37. [DOI: 10.1016/j.exppara.2009.04.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2009] [Revised: 04/07/2009] [Accepted: 04/12/2009] [Indexed: 11/28/2022]
|
18
|
Pena SDJ, Machado CR, Macedo AM. Trypanosoma cruzi: ancestral genomes and population structure. Mem Inst Oswaldo Cruz 2009; 104 Suppl 1:108-14. [PMID: 19753465 DOI: 10.1590/s0074-02762009000900016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2009] [Accepted: 06/01/2009] [Indexed: 11/22/2022] Open
|
19
|
Venegas J, Coñoepan W, Pichuantes S, Miranda S, Jercic MI, Gajardo M, Sánchez G. Phylogenetic analysis of microsatellite markers further supports the two hybridization events hypothesis as the origin of the Trypanosoma cruzi lineages. Parasitol Res 2009; 105:191-9. [DOI: 10.1007/s00436-009-1386-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Accepted: 02/26/2009] [Indexed: 11/28/2022]
|
20
|
Ekanayake DK, Cipriano MJ, Sabatini R. Telomeric co-localization of the modified base J and contingency genes in the protozoan parasite Trypanosoma cruzi. Nucleic Acids Res 2007; 35:6367-77. [PMID: 17881368 PMCID: PMC2095807 DOI: 10.1093/nar/gkm693] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Revised: 08/14/2007] [Accepted: 08/22/2007] [Indexed: 12/20/2022] Open
Abstract
Base J or beta-d-glucosylhydroxymethyluracil is a modification of thymine residues within the genome of kinetoplastid parasites. In organisms known to contain the modified base, J is located mainly within the telomeric repeats. However, in Trypanosoma brucei, a small fraction of J is also located within the silent subtelomeric variant surface glycoprotein (VSG) gene expression sites, but not in the active expression site, suggesting a role for J in regulating telomeric genes involved in pathogenesis. With the identification of surface glycoprotein genes adjacent to telomeres in the South American Trypanosome, Trypanosoma cruzi, we became interested in the telomeric distribution of base J. Analysis of J and telomeric repeat sequences by J immunoblots and Southern blots following DNA digestion, reveals approximately 25% of J outside the telomeric repeat sequences. Moreover, the analysis of DNA sequences immunoprecipitated with J antiserum, localized J within subtelomeric regions rich in life-stage-specific surface glycoprotein genes involved in pathogenesis. Interestingly, the pattern of J within these regions is developmentally regulated. These studies provide a framework to characterize the role of base J in the regulation of telomeric gene expression/diversity in T. cruzi.
Collapse
Affiliation(s)
| | | | - Robert Sabatini
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, USA
| |
Collapse
|
21
|
Iwagami M, Higo H, Miura S, Yanagi T, Tada I, Kano S, Agatsuma T. Molecular phylogeny of Trypanosoma cruzi from Central America (Guatemala) and a comparison with South American strains. Parasitol Res 2007; 102:129-34. [PMID: 17828552 DOI: 10.1007/s00436-007-0739-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Accepted: 08/21/2007] [Indexed: 11/30/2022]
Abstract
Molecular phylogenetic analysis was carried out for 21 strains of Trypanosoma cruzi, nine of which were obtained from Guatemala and 12 from South America. Phylogenetic trees were constructed using the nucleotide sequences of two nuclear gene regions, dihydrofolate reductase-thymidylate synthase (DHFR-TS) and trypanothione reductase (TR), and contiguous portions of two mitochondrial genes, cytochrome oxidase subunit II (COII) and reduced nicotinamide adenine dinucleotide dehydrogenase subunit 1 (ND1). Possible genetic exchange between the rather divergent lineages of T. cruzi II from South America was suggested in the trees of the two nuclear genes. T. cruzi I strains obtained from Guatemala and Colombia were identical in all the genes examined, but other T. cruzi I isolates from South America were rather polymorphic in the DHFR-TS and mitochondrial genes. No genetic exchange was identified between T. cruzi I populations from Central and South America in the present study.
Collapse
Affiliation(s)
- M Iwagami
- Department of Environmental Health Science, Kochi University School of Medicine, Oko, Nankoku, Kochi, 783-8505, Japan
| | | | | | | | | | | | | |
Collapse
|
22
|
Análisis de polimorfismos en los genes tripanotión reductasa y cruzipaína en cepas colombianas de Trypanosoma cruzi. BIOMEDICA 2007. [DOI: 10.7705/biomedica.v27i1.248] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
23
|
Pérez-Escobar M, Cevallos AM, Espinoza B, Espinosa N, Martínez I, Hernández R. Trypanosoma cruzi ribosomal protein S4: characterization of its coding locus, analysis of transcripts, and antigenicity of the protein. Mem Inst Oswaldo Cruz 2007; 102:473-9. [PMID: 17612768 DOI: 10.1590/s0074-02762007005000031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Accepted: 03/07/2007] [Indexed: 01/23/2023] Open
Abstract
Two allelic genomic fragments containing ribosomal protein S4 encoding genes (rpS4) from Trypanosoma cruzi (CL-Brener strain) were isolated and characterized. One allele comprises two complete tandem repeats of a sequence encoding an rpS4 gene. In the other, only one rpS4 gene is found. Sequence comparison to the accessed data in the genome project database reveals that our two-copy allele corresponds to a variant haplotype. However, the deduced aminoacid sequence of all the gene copies is identical. The rpS4 transcripts processing sites were determined by comparison of genomic sequences with published cDNA data. The obtained sequence data demonstrates that rpS4 genes are expressed in epimastigotes, amastigotes, and trypomastigotes. A recombinant version of rpS4 was found to be an antigenic: it was recognized by 62.5% of the individuals with positive serology for T. cruzi and by 93.3% of patients with proven chronic chagasic disease.
Collapse
Affiliation(s)
- Mariana Pérez-Escobar
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, D. F., 04510, México
| | | | | | | | | | | |
Collapse
|
24
|
Abstract
AbstractChagas disease, caused by the obligate unicellular parasite Trypanosoma cruzi, presents itself in a diverse collection of clinical manifestations, ranging from severe, fatal heart and digestive tract pathologies to unapparent or minor alterations that do not compromise survival. Over the years, a number of mechanisms have been proposed to explain the pathogenesis of chagasic tissue lesions, all of which have faced some criticism or been received with skepticism. This article excludes the autoimmunity hypothesis for Chagas disease because it has been extensively reviewed elsewhere, and summarizes the various alternative hypotheses that have been advanced over the years. For each of these hypotheses, an outline of its main tenets and key findings that support them is presented. This is followed by the results and comments that have challenged them and the caveats that stand on their way to wider acceptance. It is hoped that this writing will draw attention to our shortcomings in understanding the pathogenesis of Chagas disease, which, unfortunately, continues to figure among the most serious health problems of the American continent.
Collapse
|
25
|
Telleria J, Lafay B, Virreira M, Barnabé C, Tibayrenc M, Svoboda M. Trypanosoma cruzi: sequence analysis of the variable region of kinetoplast minicircles. Exp Parasitol 2006; 114:279-88. [PMID: 16730709 DOI: 10.1016/j.exppara.2006.04.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 04/11/2006] [Accepted: 04/11/2006] [Indexed: 11/16/2022]
Abstract
The comparisons of 170 sequences of kinetoplast DNA minicircle hypervariable region obtained from 19 stocks of Trypanosoma cruzi and 2 stocks of Trypanosoma cruzi marenkellei showed that only 56% exhibited a significant homology one with other sequences. These sequences could be grouped into homology classes showing no significant sequence similarity with any other homology group. The 44% remaining sequences thus corresponded to unique sequences in our data set. In the DTU I ("Discrete Typing Units") 51% of the sequences were unique. In contrast, in the DTU IId, 87.5% of sequences were distributed into three classes. The results obtained for T. cruzi marinkellei, showed that all sequences were unique, without any similarity between them and T. cruzi sequences. Analysis of palindromes in all sequence sets show high frequency of the EcoRI site. Analysis of repetitive sequences suggested a common ancestral origin of the kDNA. The editing mechanism that occurs in kinetoplastidae is discussed.
Collapse
Affiliation(s)
- Jenny Telleria
- Laboratoire de Génétique et Evolution des Maladies Infectieuses, UMR CNRS-IRD 2724 and UR IRD 165, Centre IRD, 911 avenue Agropolis, BP 64501, 34394 Montpellier Cedex 5, France.
| | | | | | | | | | | |
Collapse
|
26
|
Broutin H, Tarrieu F, Tibayrenc M, Oury B, Barnabé C. Phylogenetic analysis of the glucose-6-phosphate isomerase gene in Trypanosoma cruzi. Exp Parasitol 2006; 113:1-7. [PMID: 16410006 DOI: 10.1016/j.exppara.2005.11.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2005] [Revised: 11/17/2005] [Accepted: 11/21/2005] [Indexed: 11/21/2022]
Abstract
Trypanosoma cruzi, the agent of Chagas disease, has a basically clonal population structure with rare hybridization events. The species is subdivided into six "Discrete Typing Units" called DTUs I, IIa-e, distributed into two major phylogenetic lineages, T. cruzi I and II (TC I and II). The glucose-6-phosphate isomerase (Gpi) is a specific isoenzymic locus that presents homozygous profiles for DTUs I, IIa-c, and typical heterozygous patterns, for DTUs IId and IIe. The gene was sequenced in 12 T. cruzi stocks and in three stocks pertaining to related species. The phylogenetic relationships observed confirm that the DTUs I, IIa-c do constitute monophyletic groups. Nevertheless, the phylogenetic hierarchy of the DTUs is not clearly resolved with the GPI gene. The hybrid status of DTUs IId and IIe was clearly supported. Sequence analysis revealed that the allele 4 present in both DTUs IIa and IIc, previously considered as unique, displayed in fact two distinct sequences, specific for each DTU. The level of recombination between alleles has been investigated.
Collapse
Affiliation(s)
- Hélène Broutin
- Institut de Recherche pour le Développement (IRD), Génétique des Maladies Infectieuses, Unité de Recherche IRD no 165/Unité Mixte de Recherche CNRS (Centre National de la Recherche Scientifique, 34394 Montpellier cedex 5, France.
| | | | | | | | | |
Collapse
|
27
|
Branche C, Ochaya S, Aslund L, Andersson B. Comparative karyotyping as a tool for genome structure analysis of Trypanosoma cruzi. Mol Biochem Parasitol 2006; 147:30-8. [PMID: 16481054 DOI: 10.1016/j.molbiopara.2006.01.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2005] [Revised: 01/06/2006] [Accepted: 01/09/2006] [Indexed: 01/22/2023]
Abstract
As a part of the Trypanosoma cruzi genome project, 239 genetic markers were hybridised to PFGE separated DNA from T. cruzi, in order to determine the number and size of chromosomes and to aid the assembly of the genome sequence. We used three strains, T. cruzi IIe CL Brener (the genome project reference strain) and two T. cruzi I strains, Sylvio X10/7 and CAI/72, to perform a comparative study of their karyotypes and to determine marker linkage. A densitometry analysis of the separations estimated the total chromosome numbers to be 55 in CL Brener and 57 in the two other strains. In all, 45 markers hybridised to single chromosomal bands and 103 markers to two bands in CL Brener, while the number of markers in Sylvio X10/7 and CAI/72 were 102/68 and 61/105, respectively. Size differences between homologous chromosomes were often large, up to 1900 kb (173%). The average difference was 36% for CL Brener and 23.5% for the T. cruzi I strains. Larger differences in CL Brener are consistent with a recent hybrid origin. Forty markers distributed into 15 linkage groups were found to identify specific chromosomes or chromosomes pairs. While the same markers are generally linked in all three strains, the sizes of the chromosomes vary extensively, indicating large chromosomal rearrangements. These data provide valuable information for the finishing of the CL Brener genome sequence.
Collapse
Affiliation(s)
- Carole Branche
- Center for Genomics and Bioinformatics, Karolinska Institutet, Berzelius väg 35, SE-171 77 Stockholm, Sweden
| | | | | | | |
Collapse
|
28
|
Abstract
Microbial ecology examines the diversity and activity of micro-organisms in Earth's biosphere. In the last 20 years, the application of genomics tools have revolutionized microbial ecological studies and drastically expanded our view on the previously underappreciated microbial world. This review first introduces the basic concepts in microbial ecology and the main genomics methods that have been used to examine natural microbial populations and communities. In the ensuing three specific sections, the applications of the genomics in microbial ecological research are highlighted. The first describes the widespread application of multilocus sequence typing and representational difference analysis in studying genetic variation within microbial species. Such investigations have identified that migration, horizontal gene transfer and recombination are common in natural microbial populations and that microbial strains can be highly variable in genome size and gene content. The second section highlights and summarizes the use of four specific genomics methods (phylogenetic analysis of ribosomal RNA, DNA-DNA re-association kinetics, metagenomics, and micro-arrays) in analysing the diversity and potential activity of microbial populations and communities from a variety of terrestrial and aquatic environments. Such analyses have identified many unexpected phylogenetic lineages in viruses, bacteria, archaea, and microbial eukaryotes. Functional analyses of environmental DNA also revealed highly prevalent, but previously unknown, metabolic processes in natural microbial communities. In the third section, the ecological implications of sequenced microbial genomes are briefly discussed. Comparative analyses of prokaryotic genomic sequences suggest the importance of ecology in determining microbial genome size and gene content. The significant variability in genome size and gene content among strains and species of prokaryotes indicate the highly fluid nature of prokaryotic genomes, a result consistent with those from multilocus sequence typing and representational difference analyses. The integration of various levels of ecological analyses coupled to the application and further development of high throughput technologies are accelerating the pace of discovery in microbial ecology.
Collapse
Affiliation(s)
- Jianping Xu
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada.
| |
Collapse
|
29
|
de Freitas JM, Augusto-Pinto L, Pimenta JR, Bastos-Rodrigues L, Gonçalves VF, Teixeira SMR, Chiari E, Junqueira ÂCV, Fernandes O, Macedo AM, Machado CR, Pena SDJ. Ancestral genomes, sex, and the population structure of Trypanosoma cruzi. PLoS Pathog 2006; 2:e24. [PMID: 16609729 PMCID: PMC1434789 DOI: 10.1371/journal.ppat.0020024] [Citation(s) in RCA: 191] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2005] [Accepted: 02/21/2006] [Indexed: 01/02/2023] Open
Abstract
Acquisition of detailed knowledge of the structure and evolution of Trypanosoma cruzi populations is essential for control of Chagas disease. We profiled 75 strains of the parasite with five nuclear microsatellite loci, 24Salpha RNA genes, and sequence polymorphisms in the mitochondrial cytochrome oxidase subunit II gene. We also used sequences available in GenBank for the mitochondrial genes cytochrome B and NADH dehydrogenase subunit 1. A multidimensional scaling plot (MDS) based in microsatellite data divided the parasites into four clusters corresponding to T. cruzi I (MDS-cluster A), T. cruzi II (MDS-cluster C), a third group of T. cruzi strains (MDS-cluster B), and hybrid strains (MDS-cluster BH). The first two clusters matched respectively mitochondrial clades A and C, while the other two belonged to mitochondrial clade B. The 24Salpha rDNA and microsatellite profiling data were combined into multilocus genotypes that were analyzed by the haplotype reconstruction program PHASE. We identified 141 haplotypes that were clearly distributed into three haplogroups (X, Y, and Z). All strains belonging to T. cruzi I (MDS-cluster A) were Z/Z, the T. cruzi II strains (MDS-cluster C) were Y/Y, and those belonging to MDS-cluster B (unclassified T. cruzi) had X/X haplogroup genotypes. The strains grouped in the MDS-cluster BH were X/Y, confirming their hybrid character. Based on these results we propose the following minimal scenario for T. cruzi evolution. In a distant past there were at a minimum three ancestral lineages that we may call, respectively, T. cruzi I, T. cruzi II, and T. cruzi III. At least two hybridization events involving T. cruzi II and T. cruzi III produced evolutionarily viable progeny. In both events, the mitochondrial recipient (as identified by the mitochondrial clade of the hybrid strains) was T. cruzi II and the mitochondrial donor was T. cruzi III.
Collapse
Affiliation(s)
- Jorge M. de Freitas
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Luiz Augusto-Pinto
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Juliana R Pimenta
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Luciana Bastos-Rodrigues
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Vanessa F Gonçalves
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Santuza M. R Teixeira
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Egler Chiari
- Departamento de Parasitologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | - Octavio Fernandes
- Departamento de Medicina Tropical, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Andréa M Macedo
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Carlos Renato Machado
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Sérgio D. J Pena
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| |
Collapse
|
30
|
Westenberger SJ, Barnabé C, Campbell DA, Sturm NR. Two Hybridization Events Define the Population Structure of Trypanosoma cruzi. Genetics 2005; 171:527-43. [PMID: 15998728 PMCID: PMC1456769 DOI: 10.1534/genetics.104.038745] [Citation(s) in RCA: 184] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Abstract
Genetic variation in Trypanosoma cruzi is likely a key determinant in transmission and pathogenesis of Chagas disease. We have examined nine loci as markers for the extant T. cruzi strains. Four distinct alleles were found for each locus, corresponding to the sequence classes present in the homozygous discrete typing units (DTUs) I, IIa, IIb, and IIc. The alleles in DTUs IIa and IIc showed a spectrum of polymorphism ranging from DTU I-like to DTU IIb-like, in addition to DTU-specific sequence variation. DTUs IId and IIe were indistinguishable, showing DTU homozygosity at one locus and heterozygosity with DTU IIb and IIc allelic sequences at eight loci. Recombination between the DTU IIb and IIc alleles is evidenced from mosaic polymorphisms. These data imply that two discrete hybridization events resulted in the formation of the current DTUs. We propose a model in which a fusion between ancestral DTU I and IIb strains gave rise to a heterozygous hybrid that homogenized its genome to become the homozygous progenitor of DTUs IIa and IIc. The second hybridization between DTU IIb and IIc strains that generated DTUs IId and IIe resulted in extensive heterozygosity with subsequent recombination of parental genotypes.
Collapse
Affiliation(s)
- Scott J Westenberger
- Department of Microbiology, Immunology & Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, 90095, USA
| | | | | | | |
Collapse
|
31
|
Abstract
The origin of sex and how sex is maintained are among the biggest puzzles in biology. Most investigations into this problem have focused on complex eukaryotes like animals and plants. This mini-review summarizes recent progress in our understanding of the evolution of sex, highlighting results from studies of experimental and natural populations of microorganisms. Increasing evidence indicates that sexual reproduction in natural populations of viruses, bacteria, and eukaryotic microbes is much more prevalent than previously thought. In addition, investigations using experimental microbial populations are providing important parameters relevant to our understanding of the origin and maintenance of sex. It is argued that microbes are excellent model organisms to explore the mechanisms responsible for the evolution of sex.
Collapse
Affiliation(s)
- Jianping Xu
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada.
| |
Collapse
|
32
|
Higo H, Miura S, Horio M, Mimori T, Hamano S, Agatsuma T, Yanagi T, Cruz-Reyes A, Uyema N, Rojas de Arias A, Matta V, Akahane H, Hirayama K, Takeuchi T, Tada I, Himeno K. Genotypic variation among lineages of Trypanosoma cruzi and its geographic aspects. Parasitol Int 2004; 53:337-44. [PMID: 15464443 DOI: 10.1016/j.parint.2004.06.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2003] [Accepted: 06/09/2004] [Indexed: 10/26/2022]
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.
Collapse
Affiliation(s)
- Hiroo Higo
- Department of Parasitology, Graduate School of Medical Sciences, Kyushu University, Maidashi 3-1-1, Higashiku, Fukuoka 812-8582, Japan.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Villarreal D, Barnabé C, Sereno D, Tibayrenc M. Lack of correlation between in vitro susceptibility to Benznidazole and phylogenetic diversity of Trypanosoma cruzi, the agent of Chagas disease. Exp Parasitol 2004; 108:24-31. [PMID: 15491545 DOI: 10.1016/j.exppara.2004.07.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2003] [Revised: 05/15/2004] [Accepted: 07/01/2004] [Indexed: 11/18/2022]
Abstract
Chagas disease remains an important health problem in Central and South America. Nitroimidazole derivative drugs like Benznidazole are commonly used to treat Trypanosoma cruzi infection. Natural variation of drug susceptibility between various T. cruzi stocks has been proposed as a possible explanation of treatment failure. Thus, the aim of this work was to determine potential correlations between in vitro Benznidazole susceptibility of different T. cruzi stocks and their genetic diversity. For this purpose, 16 natural stocks representing the overall genetic diversity of the parasite were analysed. Genetic characterisation was assessed by both random amplified polymorphic DNA (RAPD) and multilocus enzyme electrophoresis (MLEE) analyses. Drug activity was determined by two complementary methods, the MTT-PMS micro-method and FACs analysis. The 50% inhibitory concentrations (IC(50)s) were determined. Important variation of IC(50) values (7.3-16.9 microM) among stocks belonging to different discrete typing units (DTUs) was recorded. Further, correlation analysis showed that natural susceptibility to Benznidazole in T. cruzi expressed as IC(50) level was not related with its genetic structure represented by the different DTUs. These results are discussed in relation with the proposed hypothesis establishing a link between genetic diversity and biological behaviour in T. cruzi.
Collapse
Affiliation(s)
- Diana Villarreal
- Génétique et Evolution des Maladies Infectieuses G.E.M.I (Ex-CEPM) UMR No. 2724 CNRS/IRD, UR 165 IRD, Centre de Recherche IRD, 911 avenue Agropolis, BP 64501, 34394 Montpellier Cedex 5, France
| | | | | | | |
Collapse
|
34
|
Telleria J, Barnabé C, Hide M, Bañuls AL, Tibayrenc M. Predominant clonal evolution leads to a close parity between gene expression profiles and subspecific phylogeny in Trypanosoma cruzi. Mol Biochem Parasitol 2004; 137:133-41. [PMID: 15279959 DOI: 10.1016/j.molbiopara.2004.05.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2004] [Revised: 02/13/2004] [Accepted: 05/03/2004] [Indexed: 11/19/2022]
Abstract
We investigated the relationships between overall phylogenetic diversity in Trypanosoma cruzi evidenced by multilocus markers (MLEE and RAPD) on the one hand, and gene expression patterns, revealed by mRNA analysis on the other hand. Nineteen laboratory-cloned stocks representative of this parasite's overall phylogenetic diversity and ecogeographical range were analyzed using random amplified differentially expressed sequences (RADES). The bat trypanosome T. cruzi marinkellei was taken as outgroup. The profiles obtained showed that RADES polymorphism cannot be considered as a simple subsample of general RAPD polymorphism. Indeed, many RADES bands were not present in general RAPD profiles, and vice versa. Phylogenies obtained from RADES on the one hand, and MLEE/RAPD on the other hand, were very similar. This suggests that in spite of the recent observation of hybrid genotypes and mosaic genes in T. cruzi, clonal evolution in this parasite has been preponderant enough on an evolutionary scale to carve the polymorphism on all types of DNA sequences, including expressed genes, although these genes are assumed to undergo natural selection pressure contrary to noncoding sequences and neutral polymorphisms.
Collapse
Affiliation(s)
- Jenny Telleria
- Génétique et Evolution des Maladies Infectieuses, Unité Mixte de Recherche 2724 Centre National de la Recherche Scientifique/Institut de Recherche pour le Développement BP64501, 34394 Montpellier Cedex 05, France
| | | | | | | | | |
Collapse
|
35
|
Macedo AM, Machado CR, Oliveira RP, Pena SDJ. Trypanosoma cruzi: genetic structure of populations and relevance of genetic variability to the pathogenesis of chagas disease. Mem Inst Oswaldo Cruz 2004; 99:1-12. [PMID: 15057339 DOI: 10.1590/s0074-02762004000100001] [Citation(s) in RCA: 213] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chagas disease, caused by the protozoan Trypanosoma cruzi, has a variable clinical course, ranging from symptomless infection to severe chronic disease with cardiovascular or gastrointestinal involvement or, occasionally, overwhelming acute episodes. The factors influencing this clinical variability have not been elucidated, but it is likely that the genetic variability of both the host and the parasite are of importance. In this work we review the the genetic structure of T. cruzi populations and analyze the importance of genetic variation of the parasite in the pathogenesis of the disease under the light of the histotropic-clonal model.
Collapse
Affiliation(s)
- Andréa M Macedo
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, 30161-970, Brasil
| | | | | | | |
Collapse
|
36
|
Diosque P, Barnabé C, Padilla AM, Marco JD, Cardozo RM, Cimino RO, Nasser JR, Tibayrenc M, Basombrío MA. Multilocus enzyme electrophoresis analysis of Trypanosoma cruzi isolates from a geographically restricted endemic area for Chagas' disease in Argentina. Int J Parasitol 2003; 33:997-1003. [PMID: 13129520 DOI: 10.1016/s0020-7519(03)00139-5] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A set of 65 Trypanosoma cruzi stocks from dogs, opossums, insect vectors and humans was isolated in a geographically restricted endemic area for Chagas' disease in Argentina and was analysed by multilocus enzyme electrophoresis for 15 loci. The results show that at least five multilocus genotypes (clonets) circulate in the study area, one belonging to T. cruzi IIe, one to T. cruzi IId and three clonets belonging to T. cruzi I; and they confirm the presence of these lineages in the country. The three clonets attributed to T. cruzi I were identical to each other for all loci except for Sod-2, where three different patterns were identified. These patterns suggest the presence of two homozygous genotypes and one heterozygous genotype. Our results also suggest association of clonet IIe with dogs, clonet IId with humans and the three T. cruzi I clonets with Didelphis albiventris. On the other hand, there was no significant association between Triatoma infestans and any particular clonet circulating in the area. These findings are consistent with the hypothesis of natural selection, from mixed populations of T. cruzi in vectors, toward more restricted populations in mammals. The epidemiological implications of the possible selection of different clonets by different mammal hosts and the significance of two homozygous genotypes and one heterozygous genotype for the Sod-2 locus are discussed.
Collapse
Affiliation(s)
- Patricio Diosque
- Laboratorio de Patología Experimental, Facultad de Ciencias de la Salud, Universidad Nacional de Salta, Calle Buenos Aires 177, CP 4400 Salta, Argentina.
| | | | | | | | | | | | | | | | | |
Collapse
|
37
|
Breniere SF, Barnabe C, Bosseno MF, Tibayrenc M. Impact of number of isoenzyme loci on the robustness of intraspecific phylogenies using multilocus enzyme electrophoresis: consequences for typing of Trypanosoma cruzi. Parasitology 2003; 127:273-81. [PMID: 12964830 DOI: 10.1017/s0031182003003573] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Thirty-one stocks of Trypanosoma cruzi, the agent of Chagas disease, representative of the genetic variability of the 2 principal lineages, that subdivide T. cruzi, were selected on the basis of previous multilocus enzyme electrophoresis analysis using 21 loci. Analyses were performed with lower numbers of loci to explore the impact of the number of loci on the robustness of the phylogenies obtained, and to identify the loci that have more impact on the phylogeny. Analyses were performed with numerical (UPGMA) and cladistical (Wagner parsimony analysis) methods for all sets of loci. Robustness of the phylogenies obtained was estimated by bootstrap analysis. Low numbers of randomly selected loci (6) were sufficient to demonstrate genetic heterogeneity among the stocks studied. However, they were unable to give reliable phylogenetic information. A higher number of randomly selected loci (15 and more) were required to reach this goal. All loci did not convey equivalent information. The more variable loci detected a greater genetic heterogeneity among the stocks, whereas the least variable loci were better for robust clustering. Finally, analysis was performed with only 5 and 9 loci bearing synapomorphic allozyme characters previously identified among larger samples of stocks. A set of 9 such loci was able to uncover both genetic heterogeneity among the stocks and to build robust phylogenies. It can therefore be recommended as a minimum set of isoenzyme loci that bring maximal information for all studies aiming to explore the phylogenetic diversity of a new set of T. cruzi stocks and for any preliminary genetic typing. Moreover, our results show that bootstrap analysis, like any statistics, is highly dependent upon the information available and that absolute bootstrap figures should be cautiously interpreted.
Collapse
Affiliation(s)
- S F Breniere
- UR 008: Pathogénie des Trypanosomatidés and Institut de Recherche pour le Développement, 911 Av. Agropolis, BP 64501, 34394 Montpellier Cedex 1, France.
| | | | | | | |
Collapse
|
38
|
Pedroso A, Cupolillo E, Zingales B. Evaluation of Trypanosoma cruzi hybrid stocks based on chromosomal size variation. Mol Biochem Parasitol 2003; 129:79-90. [PMID: 12798509 DOI: 10.1016/s0166-6851(03)00096-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Although all classical lines of evidence point to the fact that Trypanosoma cruzi has a predominantly clonal evolution, accumulating data show that some T. cruzi stocks are the result of hybridisation events. We evaluated whether chromosomal polymorphism would give evolutionary information on hybrid isolates. Twenty-three coding sequences were mapped on the chromosomes of nine parasite stocks, four of which are putative hybrids (CL Brener and rDNA group 1/2). Phenetic analyses of karyotype data were based on the absolute chromosomal size difference index (aCSDI), a method that assumes that the genomic distance between two organisms is the sum of the size differences between their homologous chromosomes. aCSDI-based dendrograms obtained from a variable number of probes (3-18 probes) defined in all the cases three clusters: two corresponding, respectively, to T. cruzi I and T. cruzi II groups; and a third one, to rDNA group 1/2. CL Brener was alternatively positioned in T. cruzi II or rDNA group 1/2 clusters. Three clusters were also observed in the dendrogram constructed with restriction fragment length polymorphism (RFLP) data from 18 probes. The topology of the chromosome and RFLP dendrograms is similar, with a significant correlation coefficient (r=0.86062; P<0.0001), supporting a strong structuring of the clusters. This study also revealed that hybrid stocks have a larger proportion of two different-sized homologous chromosomes, as compared with non-hybrid strains. Overall, our results show that chromosomes are valuable characters for identification of evolutionary groups, in particular, T. cruzi hybrid organisms.
Collapse
Affiliation(s)
- Aurélio Pedroso
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Avenida Professor Lineu Prestes, 748, CEP 05508-000, São Paulo SP, Brazil
| | | | | |
Collapse
|
39
|
Sturm NR, Vargas NS, Westenberger SJ, Zingales B, Campbell DA. Evidence for multiple hybrid groups in Trypanosoma cruzi. Int J Parasitol 2003; 33:269-79. [PMID: 12670512 DOI: 10.1016/s0020-7519(02)00264-3] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A role for parasite genetic variability in the spectrum of Chagas disease is emerging but not yet evident, in part due to an incomplete understanding of the population structure of Trypanosoma cruzi. To investigate further the observed genotypic variation at the sequence and chromosomal levels in strains of standard and field-isolated T. cruzi we have undertaken a comparative analysis of 10 regions of the genome from two isolates representing T. cruzi I (Dm28c and Silvio X10) and two from T. cruzi II (CL Brener and Esmeraldo). Amplified regions contained intergenic (non-coding) sequences from tandemly repeated genes. Multiple nucleotide polymorphisms correlated with the T. cruzi I/T. cruzi II classification. Two intergenic regions had useful polymorphisms for the design of classification probes to test on genomic DNA from other known isolates. Two adjacent nucleotide polymorphisms in HSP 60 correlated with the T. cruzi I and T. cruzi II distinction. 1F8 nucleotide polymorphisms revealed multiple subdivisions of T. cruzi II: subgroups IIa and IIc displayed the T. cruzi I pattern; subgroups IId and IIe possessed both the I and II patterns. Furthermore, isolates from subgroups IId and IIe contained the 1F8 polymorphic markers on different chromosome bands supporting a genetic exchange event that resulted in chromosomes V and IX of T. cruzi strain CL Brener. Based on these analyses, T. cruzi I and subgroup IIb appear to be pure lines, while subgroups IIa/IIc and IId/IIe are hybrid lines. These data demonstrate for the first time that IIa/IIc are hybrid, consistent with the hypothesis that genetic recombination has occurred more than once within the T. cruzi lines.
Collapse
Affiliation(s)
- Nancy R Sturm
- Department of Microbiology, Immunology and Molecular Genetics, University of California at Los Angeles, 609 Charles E. Young Drive East, Los Angeles, CA 90095-1489, USA
| | | | | | | | | |
Collapse
|
40
|
Bastrenta B, Mita N, Buitrago R, Vargas F, Flores M, Machane M, Yacsik N, Torrez M, Le Pont F, Brenière F. Human mixed infections of Leishmania spp. and Leishmania-Trypanosoma cruzi in a sub Andean Bolivian area: identification by polymerase chain reaction/hybridization and isoenzyme. Mem Inst Oswaldo Cruz 2003; 98:255-64. [PMID: 12764443 DOI: 10.1590/s0074-02762003000200015] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Parasites belonging to Leishmania braziliensis, Leishmania donovani, Leishmania mexicana complexes and Trypanosoma cruzi (clones 20 and 39) were searched in blood, lesions and strains collected from 28 patients with active cutaneous leishmaniasis and one patient with visceral leishmaniasis. PCR-hybridization with specific probes of Leishmania complexes (L. braziliensis, L. donovani and L. mexicana) and T. cruzi clones was applied to the different DNA samples. Over 29 patients, 8 (27.6%) presented a mixed infection Leishmania complex species, 17 (58.6%) a mixed infection Leishmania-T. cruzi, and 4 (13.8%) a multi Leishmania-T. cruzi infection. Several patients were infected by the two Bolivian major clones 20 and 39 of T. cruzi (44.8%). The L. braziliensis complex was more frequently detected in lesions than in blood and a reverse result was observed for L. mexicana complex. The polymerase chain reaction-hybridization design offers new arguments supporting the idea of an underestimated rate of visceral leishmanisis in Bolivia. Parasites were isolated by culture from the blood of two patients and lesions of 10 patients. The UPGMA (unweighted pair-group method with arithmetic averages) dendrogram computed from Jaccard's distances obtained from 11 isoenzyme loci data confirmed the presence of the three Leishmania complexes and undoubtedly identified human infections by L. (V.) braziliensis, L. (L.) chagasi and L. (L.) mexicana species. Additional evidence of parasite mixtures was visualized through mixed isoenzyme profiles, L. (V.) braziliensis-L. (L.) mexicana and Leishmania spp.-T. cruzi. The epidemiological profile in the studied area appeared more complex than currently known. This is the first report of parasitological evidence of Bolivian patients with trypanosomatidae multi infections and consequences on the diseases' control and patient treatments are discussed.
Collapse
Affiliation(s)
- B Bastrenta
- Universidad Mayor San Andrès, Instituto Boliviano de Biología de Altura, La Paz, Bolivia.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Brisse S, Henriksson J, Barnabé C, Douzery EJP, Berkvens D, Serrano M, De Carvalho MRC, Buck GA, Dujardin JC, Tibayrenc M. Evidence for genetic exchange and hybridization in Trypanosoma cruzi based on nucleotide sequences and molecular karyotype. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2003; 2:173-83. [PMID: 12797979 DOI: 10.1016/s1567-1348(02)00097-7] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Trypanosoma cruzi is thought to undergo predominant clonal evolution, as determined by population genetics studies. However, this model does not exclude occasional recombination, which existence is strongly suggested by several recent studies. We sequenced a portion of the maxicircle cytochrome b (CYb) gene and of the nuclear rRNA promoter region from representative strains of six T. cruzi genetic lineages isolated from anthroponotic environments and man (lineages IIb, IId and IIe), sylvatic environments (lineages IIa and IIc) or both (lineage I). Phylogenetic analyses based on the two genes were incongruent. Remarkably, in lineage IIe, CYb and rRNA sequences were very closely related to those of lineages IIc and IIb, respectively. One stock of lineage IId showed rRNA sequence heterogeneity, with both IIb-like and IIc-like copies. Analysis of the size variation of six distinct pairs of putative homologous chromosomes revealed a bimodal distribution of chromosomal sizes across T. cruzi. Notably, stocks of lineages IId and IIe had several chromosomal pairs distributed in distinct modes, with the corresponding modes individually found in lineages IIb and IIc. Together, these data indicate the origin of lineages IId and IIe by hybridization between representatives of lineages IIb and IIc. CYb and rRNA sequences clustered into three and four major lineages, respectively. Data were in agreement with the distinction of six genetic lineages, but not with their proposed grouping into two primary lineages, as lineage II was not monophyletic. Based on a CYb substitution rate of 1% per million years (Myr), the major lineages are estimated to have diverged around 10 million years ago.
Collapse
Affiliation(s)
- Sylvain Brisse
- Génétique des Maladies Infectieuses, UMR CNRS/IRD No. 9926, Institut de Recherches pour le Dévelopement, Montpellier, France.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Abstract
The question of population structure in parasitic protozoa has recently gained a renewed topicality with significant contributions on medically important pathogens, such as Plasmodium falciparum, Toxoplasma gondii and Cryptosporidium parvum. The proposals that initiated this debate are reviewed here and the subsequent developments of the clonal theory, in light of recent contributions, are examined.
Collapse
Affiliation(s)
- Michel Tibayrenc
- UR Génétique des Maladies Infectieuses, UMR Centre National de la Recherche Scientifique/Institut de Recherche pour le Développement 9926, IRD, BP 64501, 34393 Montpellier Cedex 5, France.
| | | |
Collapse
|
43
|
Thomaz Soccol V, Barnabe C, Castro E, Luz E, Tibayrenc M. Trypanosoma cruzi: isoenzyme analysis suggests the presence of an active Chagas sylvatic cycle of recent origin in Paraná State, Brazil. Exp Parasitol 2002; 100:81-6. [PMID: 12054697 DOI: 10.1016/s0014-4894(02)00009-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Thirty-one trypanosomatid stocks were isolated from various sylvatic hosts and vectors in two different regions from the Paraná State of Brazil. The stocks were analyzed by multilocus enzyme electrophoresis (MLEE) on cellulose acetate plates (22 genetic loci). All stocks were unambiguously attributed to Trypanosoma cruzi, and were found to be closely related to the formerly described zymodeme I (TC1 subgroup of T. cruzi). By comparison with other sylvatic cycles with similar sample sizes (Southern USA, Colombia, French Guiana), genetic variability among these stocks was very limited, with only two variable loci out of 22, and only three different multilocus genotypes. Population structure of T. cruzi in these cycles appears to correspond to a set of very closely related clonal genotypes. This very limited genetic variability could be due to a recent foundation of these populations (founder effect). The implications of an active Chagas sylvatic cycle in this area are discussed.
Collapse
Affiliation(s)
- V Thomaz Soccol
- Laboratório de Parasitologia Molecular, Departamento de Patologia Básica, Universidade Federal do Paraná, Centro Politécnico Jardim das Américas, CEP 81531-990, Brazil.
| | | | | | | | | |
Collapse
|
44
|
Kawashita SY, Sanson GF, Fernandes O, Zingales B, Briones MR. Maximum-likelihood divergence date estimates based on rRNA gene sequences suggest two scenarios of Trypanosoma cruzi intraspecific evolution. Mol Biol Evol 2001; 18:2250-9. [PMID: 11719574 DOI: 10.1093/oxfordjournals.molbev.a003771] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The phylogenetic relationships of Trypanosoma cruzi strains were inferred using maximum-likelihood from complete 18S rDNA sequences and D7-24Salpha rDNA regions from 20 representative strains of T. cruzi. For this we sequenced the 18S rDNA of 14 strains and the D7-24Salpha rDNA of four strains and aligned them to previously published sequences. Phylogenies inferred from these data sets identified four groups, named Riboclades 1, 2, 3, and 4, and a basal dichotomy that separated Riboclade 1 from Riboclades 2, 3, and 4. Substitution models and other parameters were optimized by hierarchical likelihood tests, and our analysis of the 18S rDNA molecular clock by the likelihood ratio test suggests that a taxa subset encompassing all 2,150 positions in the alignment supports rate constancy among lineages. The present analysis supports the notion that divergence dates of T. cruzi Riboclades can be estimated from 18S rDNA sequences and therefore, we present alternative evolutionary scenarios based on two different views of T. cruzi intraspecific divergence. The first assumes a faster evolutionary rate, which suggests that the divergence between T. cruzi I and II and the extant strains occurred in the Tertiary period (37-18 MYA). The other, which supports the hypothesis that the divergence between T. cruzi I and II occurred in the Cretaceous period (144-65 MYA) and the divergence of the extant strains occurred in the Tertiary period of the Cenozoic era (65-1.8 MYA), is consistent with our previously proposed hypothesis of divergence by geographical isolation and mammalian host coevolution.
Collapse
Affiliation(s)
- S Y Kawashita
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, Brazil
| | | | | | | | | |
Collapse
|
45
|
Veloso VM, Carneiro CM, Toledo MJ, Lana M, Chiari E, Tafuri WL, Bahia MT. Variation in susceptibility to benznidazole in isolates derived from Trypanosoma cruzi parental strains. Mem Inst Oswaldo Cruz 2001; 96:1005-11. [PMID: 11685270 DOI: 10.1590/s0074-02762001000700021] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In this work, the susceptibility to benznidazole of two parental Trypanosoma cruzi strains, Colombian and Berenice-78, was compared to isolates obtained from dogs infected with these strains for several years. In order to evaluate the susceptibility to benznidazole two groups of mice were infected with one of five distinct populations isolated from dogs as well as the two parental strains of T. cruzi. The first group was treated with benznidazole during the acute phase and the second remained untreated controls. The animals were considered cured when parasitological and serological tests remained persistently negative. Mice infected with the Colombian strain and its isolates Colombian (A and B) did not cure after treatment. On the other hand, all animals infected with Berenice-78 were cured by benznidazole treatment. However, 100%, 50% and 70% of cure rates were observed in animals infected with the isolates Berenice-78 B, C and D, respectively. No significant differences were observed in serological profile of infected control groups, with all animals presenting high antibody levels. However, the ELISA test showed differences in serological patterns between mice inoculated with the different T. cruzi isolates and treated with benznidazole. This variability was dependent on the T. cruzi population used and seemed to be associated with the level of resistance to benznidazole.
Collapse
Affiliation(s)
- V M Veloso
- Departamento de Ciências Biológicas, ICEB, Universidade Federal de Ouro Preto, Ouro Preto, MG, 35400-000, Brasil
| | | | | | | | | | | | | |
Collapse
|
46
|
Affiliation(s)
- J Votýpka
- Institute of Parasitology, Czech Academy of Sciences, Branisovská 31, Ceské Budĕjovice, 37005, Czech Republic
| | | | | |
Collapse
|
47
|
Hernández R, Herrera J, Bosseno MF, Brenière SF, Espinoza B. Trypanosoma cruzi: data supporting clonality in Mexican stocks. J Parasitol 2001; 87:1178-81. [PMID: 11695391 DOI: 10.1645/0022-3395(2001)087[1178:tcdsci]2.0.co;2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
To further study genetic heterogeneity of Mexican stocks of Trypanosoma cruzi, genomic Southern analyses from 54 Mexican isolates and 5 South American reference stocks were carried out. The membranes were hybridized with a homologous cDNA clone from the ribosomal protein S4 that identifies allelic bands from a single gene type locus. These allelic bands were sequentially numbered depending on their relative size. Mexican T. cruzi stocks were quite homogeneous: 31 cases (57%) showed a homozygous genotype 3/3, and 21 isolates (38%) exhibited the heterozygote genotype 2/3. Just 2 Mexican stocks (3%) showed a different genotype 2/5, but the potential parental homozygous 2/2 was never observed. Being that T. cruzi is a diploid organism, the apparent absence of the presumptive parental homozygous genotype 2/2 argues against sexual reproduction within the population, at least as a common event. Therefore, these data support a clonal population structure of T. cruzi in Mexico.
Collapse
Affiliation(s)
- R Hernández
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México City
| | | | | | | | | |
Collapse
|
48
|
Machado CA, Ayala FJ. Nucleotide sequences provide evidence of genetic exchange among distantly related lineages of Trypanosoma cruzi. Proc Natl Acad Sci U S A 2001; 98:7396-401. [PMID: 11416213 PMCID: PMC34680 DOI: 10.1073/pnas.121187198] [Citation(s) in RCA: 264] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Simple phylogenetic tests were applied to a large data set of nucleotide sequences from two nuclear genes and a region of the mitochondrial genome of Trypanosoma cruzi, the agent of Chagas' disease. Incongruent gene genealogies manifest genetic exchange among distantly related lineages of T. cruzi. Two widely distributed isoenzyme types of T. cruzi are hybrids, their genetic composition being the likely result of genetic exchange between two distantly related lineages. The data show that the reference strain for the T. cruzi genome project (CL Brener) is a hybrid. Well-supported gene genealogies show that mitochondrial and nuclear gene sequences from T. cruzi cluster, respectively, in three or four distinct clades that do not fully correspond to the two previously defined major lineages of T. cruzi. There is clear genetic differentiation among the major groups of sequences, but genetic diversity within each major group is low. We estimate that the major extant lineages of T. cruzi have diverged during the Miocene or early Pliocene (3-16 million years ago).
Collapse
Affiliation(s)
- C A Machado
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA.
| | | |
Collapse
|
49
|
Abstract
Trypanosoma brucei is still the only kinetoplastid known to undergo genetic exchange, but it seems unreasonable to suppose that it evolved this process all by itself. The position of T. brucei on a molecular phylogenetic tree constructed from 18S ribosomal RNA gene sequences offers no clues to the likely existence of genetic exchange in trypanosome species other than the Salivaria, because this group of trypanosomes appears to have diverged from the rest a very long time ago. Antigenic variation is one characteristic shared by the Salivaria, which has been particularly well-studied in T. brucei. The large proportion of the genome devoted to variant antigen genes and related sequences in T. brucei, suggests a possible role for genetic exchange in enhancing the diversity of the repertoire. Alternatively, genetic exchange may counter potential excessive double-strand DNA damage brought about by the DNA rearrangements associated with antigenic variation. The remarkable biparental inheritance of organelle DNA (=kinetoplast DNA) in T. brucei is without precedent in other eukaryotes. The result of genetic exchange is to enhance the heterogeneity of the kinetoplast DNA minicircles.
Collapse
Affiliation(s)
- W Gibson
- School of Biological Sciences, University of Bristol, Woodland Road, BS8 1UG, Bristol, UK. w,
| |
Collapse
|
50
|
Acosta N, Samudio M, López E, Vargas F, Yaksic N, Brenière SF, Rojas de Arias A. Isoenzyme profiles of Trypanosoma cruzi stocks from different areas of Paraguay. Mem Inst Oswaldo Cruz 2001; 96:527-33. [PMID: 11391427 DOI: 10.1590/s0074-02762001000400015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Twenty one Trypanosoma cruzi stocks from humans, domiciliary triatomines and one sylvatic animal of different areas of Paraguay were subjected to isoenzyme analysis. Thirteen enzyme systems (15 loci in total) were studied. MN cl2 (clonets 39) and SO34 cl4 (clonets 20) were used as references. Relationships between stocks were depicted by an UPGMA dendrogram constructed using the Jaccard's distances matrix. Among the Paraguayan stocks 14 zymodemes were identified (Par1 to Par14), Par 5 being the most frequent. Polymorphism rate and clonal diversity were 0.73 and 0.93, respectively. Average number of alleles per polymorphic locus was 2.5 (range 2-4). These measurements show a high diversity, which is confirmed by the dendrogram topology. All stocks belong to the same lineage, as MN cl2 reference strain (T. cruzi II). Moreover three distinct subgroups were identified and two of them correspond to Brazilian and Bolivian zymodemes, respectively. The third subgroup, the most common in Paraguay, is related to Tulahuen stock. The large geographical distribution of some zymodemes agrees with the hypothesis of clonality for T. cruzi populations. However sample size was not adequate to detect genetic recombination in any single locality.
Collapse
Affiliation(s)
- N Acosta
- Departamento de Medicina Tropical, Instituto de Investigaciones en Ciencias de la Salud, UNA, Asunción, Paraguay
| | | | | | | | | | | | | |
Collapse
|