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

High-throughput analysis of the Trypanosoma cruzi minicirculome (mcDNA) unveils structural variation and functional diversity

Trypanosoma cruzi causes Chagas disease and has a unique extranuclear genome enclosed in a structure called the kinetoplast, which contains circular genomes known as maxi- and minicircles. While the structure and function of maxicircles are well-understood, many aspects of minicircles remain to be discovered. Here, we performed a high-throughput analysis of the minicirculome (mcDNA) in 50 clones isolated from Colombia's diverse T. cruzi I populations. Results indicate that mcDNA comprises four diverse subpopulations with different structures, lengths, and numbers of interspersed semi-conserved (previously termed ultra-conserved regions mHCV) and hypervariable (mHVPs) regions. Analysis of mcDNA ancestry and inter-clone differentiation indicates the interbreeding of minicircle sequence classes is placed along diverse strains and hosts. These results support evidence of the multiclonal dynamics and random bi-parental segregation. Finally, we disclosed the guide RNA repertoire encoded by mcDNA at a clonal scale, and several attributes of its abundance and function are discussed.

Glycosylation of Trypanosoma cruzi TcI antigen reveals recognition by chagasic sera

Chagas disease is considered the most important parasitic disease in Latin America. The protozoan agent, Trypanosoma cruzi, comprises six genetic lineages, TcI-TcVI. Genotyping to link lineage(s) to severity of cardiomyopathy and gastrointestinal pathology is impeded by the sequestration and replication of T. cruzi in host tissues. We describe serology specific for TcI, the predominant lineage north of the Amazon, based on expression of recombinant trypomastigote small surface antigen (gTSSA-I) in the eukaryote Leishmania tarentolae, to allow realistic glycosylation and structure of the antigen. Sera from TcI-endemic regions recognised gTSSA-I (74/146; 50.7%), with no cross reaction with common components of gTSSA-II/V/VI recombinant antigen. Antigenicity was abolished by chemical (periodate) oxidation of gTSSA-I glycosylation but retained after heat-denaturation of conformation. Conversely, non-specific recognition of gTSSA-I by non-endemic malaria sera was abolished by heat-denaturation. TcI-specific serology facilitates investigation between lineage and diverse clinical presentations. Glycosylation cannot be ignored in the search for immunogenic antigens.

Evaluation of the multispecies coalescent method to explore intra-Trypanosoma cruzi I relationships and genetic diversity

Chagas Disease is a zoonosis caused by the parasite Trypanosoma cruzi. Several high-resolution markers have subdivided T. cruzi taxon into at least seven lineages or Discrete Typing Units (DTUs) (TcI-TcVI and TcBat). Trypanosoma cruzi I is the most diverse and geographically widespread DTU. Recently a TcI genotype related to domestic cycles was proposed and named as TcIDOM. Herein, we combined traditional markers and housekeeping genes and applied a Multispecies Coalescent method to explore intra-TcI relationships, lineage boundaries and genetic diversity in a random set of isolates and DNA sequences retrieved from Genbank from different countries in the Americas. We found further evidence supporting TcIDOM as an independent and emerging genotype of TcI at least in Colombia and Venezuela. We also found evidence of high phylogenetic incongruence between parasite's gene trees (including introgression) and embedded species trees, and a lack of genetic structure among geography and hosts, illustrating the complex dynamics and epidemiology of TcI across the Americas. These findings provide novel insights into T. cruzi systematics and epidemiology and support the need to assess parasite diversity and lineage boundaries through hypothesis testing using different approaches to those traditionally employed, including the Bayesian Multispecies coalescent method.

Activity in vitro and in vivo against Trypanosoma cruzi of a furofuran lignan isolated from Piper jericoense

Piperaceae species are abundant in the tropics and are important components of secondary vegetation. Many of these plants have received considerable attention due to their wide range of biological activities. Here, the trypanocidal activity of extracts and fractions with different polarities obtained from Colombian Piper jericoense plant was evaluated. A furofuran lignan, (1S,3aS,4S,6aS)-1-(3',4'-dimethoxyphenyl)-4-(3″,4″-methylendioxyphenyl)hexahydrofuro[3,4-c]furan, (1), was isolated from Colombian Piper jericoense leaves ethyl acetate extract. Its relative configuration at the stereogenic centers was established on the basis of various spectroscopic analyses, including 1D- (1H, 13C, and DEPT) and 2D-NMR (COSY, NOESY, HMQC and HMBC) and a 2D INADEQUATE NMR experiment as well as by comparison of their spectral data with those of related compounds such as (+)-Kobusin (2). The activity against Trypanosoma cruzi indicated that compound 1 was active against all parasite forms (epimastigote, amastigote and trypomastigote) and presented lower toxicity than the reference drug, benznidazole (Bz), evidenced by a selective index of 18.4 compared to that of Bz, which was 6.7. Moreover, this compound inhibited the infectious process, and it was active in infected mice in the acute phase. This compound significantly inhibited the T. cruzi Fe-SOD enzyme, whereas Cu/Zn-SOD from human cells was not affected. Ultrastructural analyses, together with metabolism-excretion studies in the parasite, were also performed to identify the possible mechanism of action of the tested compound. Interestingly, the lignan affected the parasite structure, but it did not alter the energetic metabolism.

The diversity of the Chagas parasite, Trypanosoma cruzi, infecting the main Central American vector, Triatoma dimidiata, from Mexico to Colombia

Little is known about the strains of Trypanosoma cruzi circulating in Central America and specifically in the most important vector in this region, Triatoma dimidiata. Approximately six million people are infected with T. cruzi, the causative agent of Chagas disease, which has the greatest negative economic impact and is responsible for ~12,000 deaths annually in Latin America. By international consensus, strains of T. cruzi are divided into six monophyletic clades called discrete typing units (DTUs TcI-VI) and a seventh DTU first identified in bats called TcBat. TcI shows the greatest geographic range and diversity. Identifying strains present and diversity within these strains is important as different strains and their genotypes may cause different pathologies and may circulate in different localities and transmission cycles, thus impacting control efforts, treatment and vaccine development. To determine parasite strains present in T. dimidiata across its geographic range from Mexico to Colombia, we isolated abdominal DNA from T. dimidiata and determined which specimens were infected with T. cruzi by PCR. Strains from infected insects were determined by comparing the sequence of the 18S rDNA and the spliced-leader intergenic region to typed strains in GenBank. Two DTUs were found: 94% of infected T. dimidiata contained TcI and 6% contained TcIV. TcI exhibited high genetic diversity. Geographic structure of TcI haplotypes was evident by Principal Component and Median-Joining Network analyses as well as a significant result in the Mantel test, indicating isolation by distance. There was little evidence of association with TcI haplotypes and host/vector or ecotope. This study provides new information about the strains circulating in the most important Chagas vector in Central America and reveals considerable variability within TcI as well as geographic structuring at this large geographic scale. The lack of association with particular vectors/hosts or ecotopes suggests the parasites are moving among vectors/hosts and ecotopes therefore a comprehensive approach, such as the Ecohealth approach that makes houses refractory to the vectors will be needed to successfully halt transmission of Chagas disease.