Genetic Diversity of Trypanosoma cruzi in Panama Inferred by Multi-locus Sequence Typing of Mitochondrial Genes

First Report of Seropositivity to Trypanosoma cruzi in Mexican Afro-Descendants from Guerrero and Oaxaca States

Mexican Afro-descendant is a population poorly studied in many aspects, between them the infectious diseases that they suffer. This population is mainly found in the country's Pacific (Oaxaca and Guerrero states) and Atlantic (Veracruz) coast. In these regions, a diversity of triatomine vectors of the Chagas disease is found. Also, all the genotypes of Trypanosoma cruzi DTUs have been reported. That is why the present study aimed to study the presence of antibodies against T. cruzi and cardiac pathology associated with the Chagas disease in the Mexican Afro-descendant population of Guerrero and Oaxaca. ELISA, Western blot, and recombinant antigen's ELISA were used to evaluate the seropositivity of these communities. Furthermore, an electrocardiographic study and evaluation of risk factors associated with T. cruzi infection in the Oaxaca and Guerrero populations were conducted. 26.77% of the analyzed population was positive for two serological tests. These percentages are higher than the previously reported for the mestizo population in similar studies. Electrocardiographic results showed cardiac disorder associated with the Chagas disease in the population. Also, risk factors were identified associated with the men's activities in the outdoor working areas.

Fifteen Years after the Definition of Trypanosoma cruzi DTUs: What Have We Learned?

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.

Revisiting gene typing and phylogeny of Trypanosoma cruzi reference strains: Comparison of the relevance of mitochondrial DNA, single-copy nuclear DNA, and the intergenic region of mini-exon gene

Chagas disease is a widespread neglected disease in Latin America. Trypanosoma cruzi, the causative agent of the disease, is currently subdivided into six DTUs (discrete typing units) named TcI-TcVI, and although no clear association has been found between parasite genetics and different clinical outcomes of the disease or different transmission cycles, genetic characterization of T. cruzi strains remains crucial for integrated epidemiological studies. Numerous markers have been used for this purpose, although without consensus. These include mitochondrial genes, single or multiple-copy nuclear genes, ribosomal RNA genes, and the intergenic region of the repeated mini-exon gene. To increase our knowledge of these gene sequences and their usefulness for strain typing, we sequenced fragments of three mitochondrial genes, nine single-copy nuclear genes, and the repeated intergenic part of the mini-exon gene by Next Generation Sequencing (NGS) on a sample constituted of 16 strains representative of T. cruzi genetic diversity, to which we added the corresponding genetic data of the 38 T. cruzi genomes fully sequenced until 2022. Our results show that single-copy nuclear genes remain the gold standard for characterizing T. cruzi strains; the phylogenetic tree from concatenated genes (3959 bp) confirms the six DTUs previously recognized and provides additional information about the alleles present in the hybrid strains. In the tree built from the three mitochondrial concatenated genes (1274 bp), three main clusters are identified, including one with TcIII, TcIV, TcV, and TcVI DTUs which are not separated. Nevertheless, mitochondrial markers remain necessary for detecting introgression and heteroplasmy. The phylogenetic tree built from the sequence alignment of the repeated mini-exon gene fragment (327 bp) displayed six clusters, but only TcI was associated with a single cluster. The sequences obtained from strains belonging to the other DTUs were scattered into different clusters. Therefore, while the mini-exon marker may bring, for some biological samples, some advantages in terms of sensibility due to its repeated nature, mini-exon sequences must be used with caution and, when possible, avoided for T. cruzi typing and phylogenetic studies.

An overview of the trypanosomatid (Kinetoplastida: Trypanosomatidae) parasites infecting several mammal species in Colombia

BACKGROUND

Trypanosomatids are among the most critical parasites for public health due to their impact on human, animal, and plant health. Diseases associated with these pathogens manifest mainly in poor and vulnerable populations, where social, environmental, and biological factors modulate the case incidence and geographical distribution.

METHODS

We used Sanger and amplicon-based next-generation sequencing (NGS) in samples from different mammals to identify trypanosomatid infections in several departments in Colombia. A total of 174 DNA samples (18 humans, 83 dogs, and 73 wild mammals) were analyzed by conventional PCR using a fragment of the heat shock protein 70 (Hsp70) gene and Sanger sequenced the positive samples. Twenty-seven samples were sent for amplicon-based NGS using the same gene fragment. Data obtained were used to perform diversity analyses.

RESULTS

One hundred and thirteen samples were positive for PCR by Hsp70 fragment; these corresponded to 22.1% Leishmania spp., 18.6% L. amazonensis, 9.7% L. braziliensis, 14.2% L. infantum, 8% L. panamensis, and 27.4% Trypanosoma cruzi. Comparison of the identified species by the two sequencing technologies used resulted in 97% concordance. Alpha and beta diversity indices were significant, mainly for dogs; there was an interesting index of coinfection events in the analyzed samples: different Leishmania species and the simultaneous presence of T. cruzi and even T. rangeli in one of the samples analyzed. Moreover, a low presence of L. braziliensis was observed in samples from wild mammals. Interestingly, to our knowledge, this is the first report of Leishmania detection in Hydrochaeris hydrochaeris (capybara) in Colombia.

CONCLUSIONS

The Hsp70 fragment used in this study is an optimal molecular marker for trypanosomatid identification in many hosts and allows the identification of different species in the same sample when amplicon-based sequencing is used. However, the use of this fragment for molecular diagnosis through conventional PCR should be carefully interpreted because of this same capacity to identify several parasites. This point is of pivotal importance in highly endemic countries across South America because of the co-circulation of different genera from the Trypanosomatidae family. The findings show an interesting starting point for One Health approaches in which coevolution and vector-host interactions can be studied.