High variability of Colombian Trypanosoma cruzi lineage I stocks as revealed by low-stringency single primer-PCR minicircle signatures

Trypanosomatid Richness Among Rats, Opossums, and Dogs in the Caatinga Biome, Northeast Brazil, a Former Endemic Area of Chagas Disease

Parasites are important components of the immense n-dimensional trophic network that connects all living beings because they, among others, forge biodiversity and deeply influence ecological evolution and host behavior. In this sense, the influence of Trypanosomatidae remains unknown. The aim of this study was to determine trypanosomatid infection and richness in rats, opossums, and dogs in the semiarid Caatinga biome. We submitted DNA samples from trypanosomatids obtained through axenic cultures of the blood of these mammals to mini exon multiplex-PCR, Sanger, and next-generation sequencing targeting the 18S rDNA gene. Phylogenetic analyses were performed to identify genetic diversity in the Trypanosomatidae family. Shannon, Simpson, equability, and beta-diversity indices were calculated per location and per mammalian host. Dogs were surveyed for trypanosomatid infection through hemocultures and serological assays. The examined mammal species of this area of the Caatinga biome exhibited an enormous trypanosomatid species/genotypes richness. Ten denoised Operational Taxonomic Units (ZOTUs), including three species (Trypanosoma cruzi, Trypanosoma rangeli and Crithidia mellificae) and one Trypanosoma sp. five genotypes/lineages (T. cruzi DTU TcI, TcII, and TcIV; T. rangeli A and B) and four DTU TcI haplotypes (ZOTU1, ZOTU2, ZOTU5, and ZOTU10 merged), as well as 13 Amplicon Sequence Variants (ASVs), including five species (T. cruzi, T. rangeli, C. mellificae, Trypanosoma dionisii, and Trypanosoma lainsoni), five genotypes/lineages (same as the ZOTUs) and six DTU TcI haplotypes (ASV, ASV1, ASV2, ASV3, ASV5 and ASV13), were identified in single and mixed infections. We observed that trypanosomatids present a broad host spectrum given that species related to a single host are found in other mammals from different taxa. Concomitant infections between trypanosomatids and new host-parasite relationships have been reported, and this immense diversity in mammals raised questions, such as how this can influence the course of the infection in these animals and its transmissibility. Dogs demonstrated a high infection rate by T. cruzi as observed by positive serological results (92% in 2005 and 76% in 2007). The absence of positive parasitological tests confirmed their poor infectivity potential but their importance as sentinel hosts of T. cruzi transmission.

Mixed infections by different Trypanosoma cruzi discrete typing units among Chagas disease patients in an endemic community in Panama

Background

Trypanosoma cruzi, the hemoparasite that causes Chagas disease, is divided into six Discrete Typing Units or DTUs: TcI-TcVI plus Tcbat. This genetic diversity is based on ecobiological and clinical characteristics associated with particular populations of the parasite. The main objective of this study was the identification of DTUs in patients with chronic chagasic infections from a mountainous rural community in the eastern region of Panama.

Methods

A total of 106 patients were tested for Chagas disease with three serological tests (ELISA, rapid test, and Western blot). Molecular diagnosis and DTU typing were carried out by conventional PCRs and qPCR targeting different genomic markers, respectively. As a control sample for the typing, 28 patients suspected to be chagasic from the metropolitan area of Panama City were included.

Results

Results showed a positivity in the evaluated patients of 42.3% (33/78); high compared to other endemic regions in the country. In the control group, 20/28 (71.43%) patients presented positive serology. The typing of samples from rural patients showed that 78.78% (26/33) corresponded to TcI, while 9.09% (3/33) were mixed infections (TcI plus TcII/V/VI). Seventy-five percent (15/20) of the patients in the control group presented TcI, and in five samples it was not possible to typify the T. cruzi genotype involved.

Conclusions

These results confirm that TcI is the main DTU of T. cruzi present in chronic chagasic patients from Panama. However, the circulation of other genotypes (TcII/V/VI) in this country is described for the first time. The eco-epidemiological characteristics that condition the circulation of TcII/V/VI, as well as the immune and clinical impact of mixed infections in this remote mountainous region should be investigated, which will help local action programs in the surveillance, prevention, and management of Chagas disease.

Trypanosoma cruzi I: Towards the need of genetic subdivision?, Part II

Chagas disease is a complex zoonosis caused by the kinetoplastid parasite Trypanosoma cruzi. This protozoan exhibits remarkable genetic diversity evinced in at least six Discrete Typing Units (DTUs) with the foreseen emergence of a genotype associated to bats (TcBat). T. cruzi I is the DTU with the broadest geographical distribution and associated to severe cardiomyopathies. In 2011, we published a review questioning the need for genetic subdivision within TcI. However, after six years of intensive research. Herein, we attempted to determine if TcI should be subdivided or not in the light of the current genetic, biological, clinical and ecological data. The future perspectives are discussed.

Dissecting the phyloepidemiology of Trypanosoma cruzi I (TcI) in Brazil by the use of high resolution genetic markers

BACKGROUND

Trypanosoma cruzi, the causal agent of Chagas disease, is monophyletic but genetically heterogeneous. It is currently represented by six genetic lineages (Discrete Typing Units, DTUs) designated TcI-TcVI. TcI is the most geographically widespread and genetically heterogeneous lineage, this as is evidenced by a wide range of genetic markers applied to isolates spanning a vast geographic range in Latin America.

METHODOLOGY/PRINCIPAL FINDINGS

In total, 78 TcI isolated from hosts and vectors distributed in 5 different biomes of Brazil, were analyzed using 6 nuclear housekeeping genes, 25 microsatellite loci and one mitochondrial marker. Nuclear markers reveal substantial genetic diversity, significant gene flow between biomes, incongruence in phylogenies, and haplotypic analysis indicative of intra-DTU genetic exchange. Phylogenetic reconstructions based on mitochondrial and nuclear loci were incongruent, and consistent with introgression. Structure analysis of microsatellite data reveals that, amongst biomes, the Amazon is the most genetically diverse and experiences the lowest level of gene flow. Investigation of population structure based on the host species/genus, indicated that Didelphis marsupialis might play a role as the main disperser of TcI.

CONCLUSIONS/SIGNIFICANCE

The present work considers a large TcI sample from different hosts and vectors spanning multiple ecologically diverse biomes in Brazil. Importantly, we combine fast and slow evolving markers to contribute to the epizootiological understanding of TcI in five distinct Brazilian biomes. This constitutes the first instance in which MLST analysis was combined with the use of MLMT and maxicircle markers to evaluate the genetic diversity of TcI isolates in Brazil. Our results demonstrate the existence of substantial genetic diversity and the occurrence of introgression events. We provide evidence of genetic exchange in TcI isolates from Brazil and of the relative isolation of TcI in the Amazon biome. We observe the absence of strict associations with TcI genotypes to geographic areas and/or host species.

Multilocus sequence typing: genetic diversity in Trypanosoma cruzi I (TcI) isolates from Brazilian didelphids

BACKGROUND

Trypanosoma cruzi is a protozoan parasite characterized by extensive genetic heterogeneity. There are currently six recognised, genetically distinct, monophyletic clades designated discrete typing units (DTUs). TcI has the broadest geographical range and most genetic diversity evidenced by a wide range of genetic markers applied to isolates spanning a vast geographical range across Latin America. However, little is known of the diversity of TcI that exists within sylvatic mammals across the geographical expanse of Brazil.

RESULTS

Twenty-nine sylvatic TcI isolates spanning multiple ecologically diverse biomes across Brazil were analyzed by the application of multilocus sequence typing (MLST) using four nuclear housekeeping genes. Results revealed extensive genetic diversity and also incongruence among individual gene trees. There was no association of intralineage genotype with geography or with any particular biome, with the exception of isolates from Caatinga that formed a single cluster. However, haplotypic analyses of METIII and LYT1 constitutive markers provided evidence of recombination events in two isolates derived from Didelphis marsupialis and D. albiventris, respectively. For diversity studies all possible combinations of markers were assessed with the objective of selecting the combination of gene targets that are most resolutive using the minimum number of genes. A panel of just three gene fragments (DHFR-TS, LYT1 and METIII) discriminated 26 out of 35 genotypes.

CONCLUSIONS

These findings showed geographical association of genotypes clustering in Caatinga but more characteristically TcI genotypes widely distributed without specific association to geographical areas or biomes. Importantly, we detected the signature of recombination events at the nuclear level evidenced by haplotypic analysis and incongruence.

Geographical, landscape and host associations of Trypanosoma cruzi DTUs and lineages

Background

The evolutionary history and ecological associations of Trypanosoma cruzi, the need to identify genetic markers that can distinguish parasite subpopulations, and understanding the parasite’s evolutionary and selective processes have been the subject of a significant number of publications since 1998, the year when the first DNA sequence analysis for the species was published.

Methods

The current analysis systematizes and re-analyzes this original research, focusing on critical methodological and analytical variables and results that have given rise to interpretations of putative patterns of genetic diversity and diversification of T. cruzi lineages, discrete typing units (DTUs), and populations, and their associations with hosts, vectors, and geographical distribution that have been interpreted as evidence for parasite subpopulation specificities.

Results

Few studies use hypothesis-driven or quantitative analysis for T. cruzi phylogeny (16/58 studies) or phylogeography (10/13). Among these, only one phylogenetic and five phylogeographic studies analyzed molecular markers directly from tissues (i.e. not from isolates). Analysis of T. cruzi DTU or lineage niche and its geographical projection demonstrate extensive sympatry among all clades across the continent and no significant niche differences among DTUs. DTU beta-diversity was high, indicating diverse host assemblages across regions, while host dissimilarity was principally due to host species turnover and to a much lesser degree to nestedness. DTU-host order specificities appear related to trophic or microenvironmental interactions.

Conclusions

More rigorous study designs and analyses will be required to discern evolutionary processes and the impact of landscape modification on population dynamics and risk for T. cruzi transmission to humans.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-016-1918-2) contains supplementary material, which is available to authorized users.

Trypanosoma cruzi-infected Panstrongylus geniculatus and Rhodnius robustus adults invade households in the Tropics of Cochabamba region of Bolivia

BACKGROUND

There are hardly any data available on the relationships between the parasite and the vector or regarding potential reservoirs involved in the natural transmission cycle of Trypanosoma cruzi in the Tropics of Cochabamba, Bolivia. Local families from communities were responsible for the capture of triatomine specimens, following a strategic methodology based on entomological surveillance with community participation developed by the National Chagas Programme of the Ministry of Health of Bolivia.

FINDINGS

We describe the collection of adult Panstrongylus geniculatus and Rhodnius robustus naturally infected with Trypanosoma cruzi from houses and from the hospital of Villa Tunari municipality. The flagellates found in the digestive tract of P. geniculatus belong to genetic lineages or DTUs TcI and TcIII, whereas only lineage DTU TcI was found in R. robustus. The detection of these vectors infected with T. cruzi reveals the vulnerability of local communities.

CONCLUSION

The results presented here highlight the risk of Chagas disease transmission in a region previously thought not to be endemic, indicating that the Tropics of Cochabamba should be placed under permanent entomological and epidemiological surveillance.

Multilocus analysis indicates that Trypanosoma cruzi I genetic substructure associated with sylvatic and domestic cycles is not an attribute conserved throughout Colombia

Trypanosoma cruzi, the causative agent of Chagas disease, has been classified into six discrete typing units (DTUs) named TcI to TcVI. Furthermore, subcontinental scale studies based on analysis of the splice leader intergenic region (SL-IR) of the mini-exon gene have subdivided TcI in five genetic groups (Ia-Ie) related to the domestic and non-domestic cycles. However, a current review of this marker among all the sequences deposited in the GenBank demonstrates no correlation between the genetic structure and the eco-epidemiological features of parasite transmission. In this study, we performed a multilocus analysis of TcI isolates from a diverse array of hosts and vectors in a wide eco-geographical area of Colombia. Sequences from SL-IR and mitochondrial cyt b genes as well as PCR-RFLP profiles for four nuclear genes were analyzed. Multilocus analysis indicates that genetic structuration associated with sylvatic and domestic cycles in Colombia is not an attribute conserved across the entire eco-geography where TcI can be found.

Trypanosoma cruzi III causing the indeterminate form of Chagas disease in a semi-arid region of Brazil

OBJECTIVE

Trypanosoma cruzi is subdivided into six discrete typing units (DTUs), TcI-TcVI. The precise identification of each can contribute to tracking wild DTUs that invade the domiciliary environment.

METHODS

Twenty T. cruzi stocks isolated from 16 chagasic patients, two Panstrongylus lutzi, one Galea spixii, and one Euphractus sexcinctus, from different localities in the State of Rio Grande do Norte, Brazil, were characterized by genotyping the 3' region of the 24Sα rRNA gene, the mitochondrial cytochrome oxidase subunit 2 gene, and the spliced leader intergenic region.

RESULTS

TcIII was identified in 18.7% (3/16) of patients from different municipalities, as well as in P. lutzi, G. spixii, and E. sexcinctus, indicating the connection between the sylvatic and domestic cycles in this Brazilian semi-arid region. TcI and TcII were also detected, in 37.5% (6/16) and 43.8% (7/16) of patients, respectively. These DTUs were associated with cardiac, digestive, and indeterminate clinical forms, while TcIII was identified only in patients with the indeterminate form.

CONCLUSIONS

The occurrence of these DTUs reveals important phylogenetic diversity in T. cruzi isolates from humans. TcIII is reported for the first time in northeastern Brazil. These findings appear to indicate an overlap between the sylvatic and domestic transmission cycles of the parasite in this region.

Exacerbated skeletal muscle inflammation and calcification in the acute phase of infection by Mexican Trypanosoma cruzi DTUI strain

A murine model was used to study the histopathological aspects and cytokine expression levels in skeletal muscle provoked by the infection with Mexican TcI strains. BALB/c mice were inoculated with the virulent Querétaro strain and the nonvirulent Ninoa strain. Parasite numbers were counted in blood and skeletal muscle at different times post-infection, and real time-PCR expression levels of the cytokines IL-12, IL-4, IL-10, IFN- γ , and TNF- α were evaluated. In the acute phase of infection, a high parasitic load, both in blood and skeletal muscle, was detected. The histopathological analyses showed an exacerbated inflammation and granulomatous-like infiltrate with the Querétaro strain. Interestingly, extensive calcification areas were observed in the skeletal muscle surrounded by inflammatory infiltrates. TNF- α and IL-10 expression exhibited a significant increase at the peak of infection. In summary, Querétaro strain, a Mexican TcI strain, is virulent enough to induce high inflammation and calcification in skeletal muscle of the hind limbs, which could be related to high expression levels of TNF- α .

Trypanosoma cruzi genotyping supports a common source of infection in a school-related oral outbreak of acute Chagas disease in Venezuela

Trypanosoma cruzi I, a discrete typing unit (DTU) found in human infections in Venezuela and other countries of the northern region of South America and in Central America, has been recently classified into five intra-DTU genotypes (Ia, Ib, Ic, Id, Ie) based on sequence polymorphisms found in the spliced leader intergenic region. In this paper we report the genotype identification of T. cruzi human isolates from one outbreak of acute orally acquired Chagas disease that occurred in a non-endemic region of Venezuela and from T. cruzi triatomine and rat isolates captured at a guava juice preparation site which was identified as the presumptive source of infection. The genotyping of all these isolates as TcId supports the view of a common source of infection in this oral Chagas disease outbreak through the ingestion of guava juice. Implications for clinical manifestations and dynamics of transmission cycles are discussed.

LSSP-PCR of Trypanosoma cruzi: how the single primer sequence affects the kDNA signature

Background

Low-stringency single specific primer PCR (LSSP-PCR) is a highly sensitive and discriminating technique that has been extensively used to genetically characterize Trypanosoma cruzi populations in the presence of large amounts of host DNA. To ensure high sensitivity, in most T. cruzi studies, the variable regions of the naturally amplified kinetoplast DNA (kDNA) minicircles were targeted, and this method translated the intraspecific polymorphisms of these molecules into specific and reproducible kDNA signatures. Although the LSSP-PCR technique is reproducible under strict assay conditions, the complex banding pattern generated can be significantly altered by even a single-base change in the target DNA. Our survey of the literature identified eight different primers with similar, if not identical, names that have been used for kDNA amplification and LSSP-PCR of T. cruzi. Although different primer sequences were used in these studies, many of the authors cited the same reference report to justify their primer choice. We wondered whether these changes in the primer sequence could affect also the parasite LSSP-PCR profiles.

Findings

To answer this question we compared the kDNA signatures obtained from three different and extensively studied T. cruzi populations with the eight primers found in the literature. Our results clearly demonstrate that even minimal modifications in the oligonucleotide sequences, especially in the 3′ or 5′ end, can significantly change the kDNA signature of a T. cruzi strain.

Conclusions

These results highlight the necessity of careful preservation of primer nomenclature and sequence when reproducing an LSSP-PCR work to avoid confusion and allow comparison of results among different laboratories.

The sylvatic transmission cycle of Trypanosoma cruzi in a rural area in the humid Chaco of Argentina

Little is known about the sylvatic transmission cycle of Trypanosoma cruzi in the Gran Chaco ecoregion. We conducted surveys to identify the main sylvatic hosts of T. cruzi, parasite discrete typing units and vector species involved in Pampa del Indio, a rural area in the humid Argentinean Chaco. A total of 44 mammals from 14 species were captured and examined for infection by xenodiagnosis and polymerase chain reaction amplification of the hyper-variable region of kinetoplast DNA minicircles of T. cruzi (kDNA-PCR). Ten (22.7%) mammals were positive by xenodiagnosis or kDNA-PCR. Four of 11 (36%) Didelphis albiventris (white-eared opossums) and six of nine (67%) Dasypus novemcinctus (nine-banded armadillos) were positive by xenodiagnosis and or kDNA-PCR. Rodents, other armadillo species, felids, crab-eating raccoons, hares and rabbits were not infected. Positive animals were highly infectious to the bugs that fed upon them as determined by xenodiagnosis. All positive opossums were infected with T. cruzi I and all positive nine-banded armadillos with T. cruzi III. Extensive searches in sylvatic habitats using 718 Noireau trap-nights only yielded Triatoma sordida whereas no bug was collected in 26 light-trap nights. Four armadillos or opossums fitted with a spool-and-line device were successfully tracked to their refuges; only one Panstrongylus geniculatus was found in an armadillo burrow. No sylvatic triatomine was infected with T. cruzi by microscopical examination or kDNA-PCR. Our results indicate that two independent sylvatic transmission cycles of T. cruzi occur in the humid Chaco. The putative vectors of both cycles need to be identified conclusively.

Trypanosoma cruzi I diversity: towards the need of genetic subdivision?

Trypanosoma cruzi the aethiological agent of Chagas disease, a complex zoonoses that affects the American continent is a genetically variable parasite subdivided into six Discrete Typing Units (DTUs). T. cruzi I is the most prevalent DTU affecting the northern countries of America with sporadical cases in the southern countries. T. cruzi I has shown great genetic diversity showing plausible subdivisions needed for this group. Recently, TcI has gained novel importance because of the lately discovered relation with cardiomyopathy manifestations that raises the importance of establishing subdivisions within this DTU.

Phylogenetic reconstruction based on Cytochrome b (Cytb) gene sequences reveals distinct genotypes within Colombian Trypanosoma cruzi I populations

Chagas disease caused by Trypanosoma cruzi comprises an important problem of public health in the Americas. This parasite has been recently divided into six Discrete Typing Units (DTUs) due to its high genetic diversity. We sequenced the Cytochorme b (Cytb) gene of 70 T. cruzi I Colombian clones finding four genotypes related to transmission cycles of Chagas disease in Colombia and also to specific hosts of T. cruzi. The genotypes herein described based on Cytb gene sequences are in accordance with those found using the mini-exon gene and reveals once again the enormous genetic diversity at sub-DTU level evidenced in T. cruzi I.

Immunological identification of Trypanosoma cruzi lineages in human infection along the endemic area

Genotyping studies show a polarized geographic distribution of Trypanosoma cruzi lineages in humans. Here, we assessed their distribution along Latin America through an immunological approach we designated Western blot (WB) assay with Trypomastigote small-surface antigen (TSSA) I and TSSA II (TSSA-WB). These antigens are expressed by T. cruzi I (TCI; now TcI) and T. cruzi II (TCII; reclassified as TcII to TcVI) parasites. TSSA-WB showed good concordance with genotyping tests. An unexpected frequency of TSSA II recognition was observed in Colombia, Venezuela, and Mexico (northern region of Latin America). In Argentina and Paraguay (southern region), immunophenotyping confirmed the already reported TCII (TcII to TcVI) dominance. The lineage distribution between these regions showed significant difference but not among countries within them (except for Colombia and Venezuela). TSSA-WB shows TCII emergence in the northern region where TCI was reported as dominant or even as the unique T. cruzi lineage infecting humans.

Direct analysis of genetic variability in Trypanosoma cruzi populations from tissues of Colombian chagasic patients

The clinical symptoms of Chagas disease are highly variable and are correlated with geographical distribution and parasite genetic group. Trypanosoma cruzi group I is associated with chagasic cardiomyopathy in Colombia and other countries in northern South America. However, in southern South America, T cruzi group II predominates and is associated with cardiomyopathy and digestive forms of the disease. The aim of this work was to determine the correlation between the genetic profiles of T cruzi groups circulating in the biological cycle and those present in tissues from patients with Chagas disease. We genotyped T cruzi in 10 heart tissue samples from patients with cardiomyopathy from a highly endemic area of Colombia. The genotyping was performed using nuclear and mitochondrial genes and low-stringency single-specific primer polymerase chain reaction. As expected, the predominant genetic group was T cruzi group I; however, we also detected T cruzi group II. Microsatellite analyses suggested a predominance of monoclonal populations, and sequence alignments showed similarities with Colombian strains. In addition, kinetoplast DNA signatures obtained by low-stringency single-specific primer polymerase chain reaction allowed us to group strains into the 2 genetic groups. Thus, we conclude that both T cruzi genetic groups are producing severe cases of Chagas disease in Colombia. We did not observe any correlation between low-stringency single-specific primer polymerase chain reaction profiles, histopathologic findings, clinical forms, and severity of Chagas disease.

Evaluation of the trypanocidal, cytotoxic and genotoxic activity of styrylquinoline analogs

Styrylquinolines isolated from Galipea longiflora have shown leishmanicidal, trypanocidal, nematocidal and antimalarial activity. Here, we propose to use analogs of these styrylquinolines to enhance the activity against Trypanosoma cruzi. Three compounds in a reduced and oxidized state were synthesized, and the activity against epimastigotes and trypomastigotes was evaluated. in addition, the cytotoxic activity and genotoxic effect were also determined. The results indicated that epimastigotes from different T. cruzi I stocks were highly sensitive to the three compounds. The PQM4 compound presented promising activity against trypomastigotes and low cytotoxic and genotoxic effects. Finally, we observed that the doublebond reduction of the lateral chain of the three carbons made on these compounds improved the activity and substantially diminished the toxicity of the compounds.

Trypanosoma cruzi I genotypes in different geographical regions and transmission cycles based on a microsatellite motif of the intergenic spacer of spliced-leader genes

The intergenic region of spliced-leader (SL-IR) genes from 105 Trypanosoma cruzi I (Tc I) infected biological samples, culture isolates and stocks from 11 endemic countries, from Argentina to the USA were characterised, allowing identification of 76 genotypes with 54 polymorphic sites from 123 aligned sequences. On the basis of the microsatellite motif proposed by Herrera et al. (2007) to define four haplotypes in Colombia, we could classify these genotypes into four distinct Tc I SL-IR groups, three corresponding to the former haplotypes Ia (11 genotypes), Ib (11 genotypes) and Id (35 genotypes); and one novel group, Ie (19 genotypes). Genotypes harbouring the Tc Ic motif were not detected in our study. Tc Ia was associated with domestic cycles in southern and northern South America and sylvatic cycles in Central and North America. Tc Ib was found in all transmission cycles from Colombia. Tc Id was identified in all transmission cycles from Argentina and Colombia, including Chagas cardiomyopathy patients, sylvatic Brazilian samples and human cases from French Guiana, Panama and Venezuela. Tc Ie gathered five samples from domestic Triatoma infestans from northern Argentina, nine samples from wild Mepraia spinolai and Mepraia gajardoi and two chagasic patients from Chile and one from a Bolivian patient with chagasic reactivation. Mixed infections by Tc Ia+Tc Id, Tc Ia+Tc Ie and Tc Id+Tc Ie were detected in vector faeces and isolates from human and vector samples. In addition, Tc Ia and Tc Id were identified in different tissues from a heart transplanted Chagas cardiomyopathy patient with reactivation, denoting histotropism. Trypanosoma cruzi I SL-IR genotypes from parasites infecting Triatoma gerstaeckeri and Didelphis virginiana from USA, T. infestans from Paraguay, Rhodnius nasutus and Rhodnius neglectus from Brazil and M. spinolai and M. gajardoi from Chile are to our knowledge described for the first time.

Genotyping of Trypanosoma cruzi sublineage in human samples from a North-East Argentina area by hybridization with DNA probes and specific polymerase chain reaction (PCR)

We have evaluated blood samples of chronic and congenital Trypanosoma cruzi-infected patients from the city of Reconquista located in the northeast of Argentina where no information was previously obtained about the genotype of infecting parasites. Fourteen samples of congenital and 19 chronical patients were analyzed by hybridization with DNA probes of minicircle hypervariable regions (mHVR). In congenital patients, 50% had single infections with TcIId, 7% single infections with TcIIe, 29% mixed infections with TcIId/e, and 7% had mixed infections with TcIId/b and 7% TcIId/b, respectively. In Chronical patients, 52% had single infections with TcIId, 11% single infections with TcIIe, 26% had mixed infections with TcIId/e, and 11% had non-identified genotypes. With these samples, we evaluated the minicircle lineage-specific polymerase chain reaction assay (MLS-PCR), which involves a nested PCR to HVR minicircle sequences and we found a correlation with hybridization probes of 96.4% for TcIId and 54.8% for TcIIe.

Evaluation of adult chronic Chagas' heart disease diagnosis by molecular and serological methods

Chagas' disease caused by Trypanosoma cruzi is endemic in Latin America. T. cruzi presents heterogeneous populations and comprises two main genetic lineages, named T. cruzi I and T. cruzi II. Diagnosis in the chronic phase is based on conventional serological tests, including indirect immunofluorescence (IIF) and enzyme-linked immunosorbent assay (ELISA), and diagnosis in the acute phase based on parasitological methods, including hemoculture. The objective of this study was to evaluate the diagnostic procedures of Chagas' disease in adult patients in the chronic phase by using a PCR assay and conventional serological tests, including TESA-blot as the gold standard. Samples were obtained from 240 clinical chronic chagasic patients. The sensitivities, compared to that of TESA-blot, were 70% for PCR using the kinetoplast region, 75% for PCR using the nuclear repetitive region, 99% for IIF, and 95% for ELISA. According to the serological tests results, we recommend that researchers assess the reliability and sensitivity of the commercial kit Chagatest ELISA recombinant, version 3.0 (Chagatest Rec v3.0; Wiener Lab, Rosario, Argentina), due to the lack of sensitivity. Based on our analysis, we concluded that PCR cannot be validated as a conventional diagnostic technique for Chagas' disease. These data have been corroborated by low levels of concordance with serology test results. It is recommended that PCR be used only for alternative diagnostic support. Using the nuclear repetitive region of T. cruzi, PCR could also be applicable for monitoring patients receiving etiologic treatment.

Haplotype identification within Trypanosoma cruzi I in Colombian isolates from several reservoirs, vectors and humans

Genetic variability in the Trypanosoma cruzi I group has recently been revealed in Colombian isolates from humans, reservoirs and vectors. Genomic rearrangements and the polymorphic regions in taxonomic markers, such as the miniexon gene, have led to the development of molecular tools to identify phylogenetic haplotypes in T. cruzi isolates. From genetic polymorphisms found in T. cruzi I isolates, they have been classified into four haplotypes according to their epidemiologic transmission cycles. Haplotype Ia is associated with domestic isolates, from Rhodnius prolixus; haplotype Ib, with the domestic and peridomestic cycle, mainly associated with Triatoma dimidiata; haplotype Ic is a poorly characterized group, which has been associated with the peridomestic cycle; and haplotype Id has been related to the sylvatic cycle. In order to demonstrate that the circulating T. cruzi I isolates in Colombia can be classified in the four proposed haplotypes, specific primers were designed on polymorphic regions of the miniexon gene's intergenic sequences. This set of primers allowed the molecular characterization of 33 Colombian isolates, classifying them into three of the four proposed haplotypes (Ia, Ib and Id). Results obtained from maximum parsimony and maximum-likelihood-based phylogenetic analyses correlated with the molecular classification of the isolates and their transmission cycles. This study brings insights into the Chagas disease epidemiology and the parasite's transmission dynamics.

Geographical clustering of Trypanosoma cruzi I groups from Colombia revealed by low-stringency single specific primer-PCR of the intergenic regions of spliced-leader genes

A low-stringency single-primer polymerase chain reaction (LSSP-PCR) typing procedure targeted to the intergenic regions of spliced-leader genes (SL) was designed to profile Trypanosoma cruzi I stocks from endemic regions of Colombia. Comparison between SL-LSSP-PCR profiles of parasite DNA from vector faeces and cultures isolated from those faeces showed more conservative signatures than profiles using LSSP-PCR targeted to the minicircle variable regions (kDNA). This was also observed by analysing 15 parasite clones from one stock as well as serial samples of a same stock after in vitro culturing or inoculation into mice. Thus, SL-LSSP-PCR appears more appropriate than kDNA-LSSP-PCR for reliable typing of major T. cruzi I groups from in vitro cultured stocks and triatomine faeces. SL-LSSP-PCR grouped 46 of 47 T. cruzi I Colombian stocks according to their geographical procedences in four clusters: Cluster Cas from Casanare Department, Cluster Mg from Northern Magdalena department, Cluster Mom from Momposina Depression in Southern Magdalena and finally Cluster NW from northwestern Colombia, including Sucre, Chocó, Córdoba and Antioquia departments. Sequence analysis identified punctual mutations among amplicons from each cluster. Within Cluster Mg, sequence polymorphism allowed association with different sylvatic vector species. Novel SL sequences and LSSP-PCR profiles are reported from T. cruzi I infecting Eratyrus cuspidatus, Panstrongylus geniculatus and Rhodnius pallescens vectors.

Biological characterization of Trypanosoma cruzi stocks from domestic and sylvatic vectors in Sierra Nevada of Santa Marta, Colombia

Sierra Nevada of Santa Marta is one of the most endemic regions of Chagas disease in Colombia. In this study, we compared the biological behavior and genetic features of Trypanosoma cruzi stocks that were isolated from domestic and sylvatic insects in this area. Rhodnius prolixus (from domestic environments) and Triatoma dimidiata (from sylvatic, peridomestic and domestic environments) are the most important vectors in this region. Genetic characterization showed that all stocks corresponded to T. cruzi I, but LSSP-PCR analyses indicated that some genotypes were present in both environments. Biological characterization in vitro showed a low growth rate in sylvatic T. cruzi stocks and in some domestic T. cruzi stocks, possibly indicating the presence of stocks with similar behavior in both transmission cycles. In parallel, in vivo behavioral analysis also indicated that T. cruzi stocks are variable and this species did not show a correlation between the environments where they were isolated. In addition, all stocks demonstrated a low mortality rate and histopathological lesions in heart, skeletal muscle and colon tissue. Moreover, our data indicated that experimentally infected chagasic mice displayed a relation between their myocardial inflammation intensity, parasitism tissue and parasite load using the qPCR. In conclusion, our results indicate that the T. cruzi stocks present in SNSM have similar biological behavior and do not show a correlation with the different transmission cycles. This could be explained by the complex transmission dynamics of T. cruzi in Sierra Nevada of Santa Marta, where hosts, vectors (e.g., T. dimidiata) and reservoirs circulate in both environments due to the close contact between the two transmission cycles, favoring environment overlapping. This knowledge is an important key to understanding the epidemiology and pathology of Chagas disease in this Colombian region. Furthermore, our findings could be of significant use in the design of control strategies restricted to a specified endemic region.

Trypanosoma cruzi: an analysis of the minicircle hypervariable regions diversity and its influence on strain typing

The current intraspecific nomenclature in Trypanosoma cruzi describes two major lineages, named T. cruzi I and T. cruzi II, and five sublineages within T. cruzi II, named IIa, IIb, IIc, IId and IIe. The polymorphism of minicircle hypervariable regions (mHVRs) of T. cruzi has been used in many studies for the molecular characterization of parasite populations directly from biological samples. However, the molecular bases that allow strain typing by these markers are still unclear. In this work we examined forty cloned mHVRs sequences of CL-Brener reference strain (IIe sublineage), and we found a predominant group of sequences, with 40% of frequency in this strain, with a 97% of identity among them. Out of the forty clones analyzed, we identified other less representative types, and a few unique ones. This predominant sequence is also present in different reference strains belonging to the other main T. cruzi lineages and sublineages (TcI, IIa, IIb, IIc and IId) although in a many thousand times lower frequency than in the CL-Brener strain, as shown by semiquantitative PCR. Similarly, predominant mHVR sequences previously described for TcIId strains, were clearly more frequent (many thousand times higher) in the IId reference strain analyzed by us (Mncl2) than within the reference strains belonging to the other lineages and sublineages. The analysis of the cloned sequences shows that more sequences than just the major one contribute to define the global pattern of mHVRs RFLP in the CL-Brener strain. The possible usefulness of these predominant sequences for typing TcIId and TcIIe sublineages by semiquantitative PCR, as well as the possible role of these sequences in genotype identification by mHVR probes are discussed.

Genetic polymorphism in Trypanosoma cruzi I isolated from Brazilian Northeast triatomines revealed by low-stringency single specific primer-polymerase chain reaction

Different molecular markers have been employed for typing Trypanosoma cruzi strains from endemic areas of Chagas disease. The low-stringency single specific primer-polymerase chain reaction (LSSP-PCR) has been a sensitive and informative technique that uses the variable region of kinetoplast DNA minicircles as a genetic marker, allowing detection of DNA sequence variation. In the present study, we analyzed the intra-lineage genetic variability of the T. cruzi strains obtained from triatomine feces collected on filter paper FTA card by LSSP-PCR. The hybridization of the PCR products with a probe for the subgenus Schizotrypanum and a clone-specific probe from Dm28c confirmed the subgenus as T. (S.) cruzi and respective lineages as T. cruzi I. Phenetic analysis showed the presence of three clusters that diverged by different coefficients of similarity. Thirteen T. cruzi I genotypes were observed circulating among Triatoma pseudomaculata and Rhodnius nasutus from peridomiciliary and natural environments in five peri-urban and urban localities of Jaguaruana, Ceará, Brazil. These data indicate the importance of the circulation of T. cruzi I genotypes among T. pseudomaculata and R. nasutus in different environments and the possible risk of Chagas disease domestic transmission.