Trypanosoma cruzi genetic diversity: impact on transmission cycles and Chagas disease

Abstract

Trypanosoma cruzi , the agent of Chagas disease (ChD), exhibits remarkable biological and genetic diversity, along with eco-epidemiological complexity. In order to facilitate communication among researchers aiming at the characterisation of biological and epidemiological aspects of T. cruzi , parasite isolates and strains were partitioned into seven discrete typing units (DTUs), TcI-TcVI and TcBat, identifiable by reproducible genotyping protocols. Here we present the potential origin of the genetic diversity of T. cruzi and summarise knowledge about eco-epidemiological associations of DTUs with mammalian reservoirs and vectors. Circumstantial evidence of a connection between T. cruzi genotype and ChD manifestations is also discussed emphasising the role of the host’s immune response in clinical ChD progression. We describe genomic aspects of DTUs focusing on polymorphisms in multigene families encoding surface antigens that play essential functions for parasite survival both in the insect vector and the mammalian host. Such antigens most probably contributed to the parasite success in establishing infections in different hosts and exploring several niches. Gaps in the current knowledge and challenges for future research are pointed out.

Genetic diversity of Trypanosoma cruzi strains isolated from chronic chagasic patients and non-human hosts in the state of São Paulo, Brazil

“…However, artificial conditions in culture media or even in vivo experimental models represent potential selective pressures for the predominance or elimination of a given parasite population. 6 , 7 This feature had already been observed from the analysis of electrophoretic profiles of DNA from different T. cruzi strains. In one of these experiments, T. cruzi strains were isolated from human hosts by blood culture and inoculated into murine models.…”

“…Correlation of results with complementary information - The correlation of molecular characterisation results with information from patients’ charts, reviews containing distribution maps and graphs of T. cruzi DTUs 4 - 7 , 9 , 33 and a previous research study 32 ) made it possible to better discriminate TcII from TcVI and allowed to suggest that, predominantly, the strains identified by the TcII/VI profile indeed correspond to TcII.…”

Parasitemia and Differential Tissue Tropism in Mice Infected with Trypanosoma cruzi Isolates Obtained from Meccus phyllosoma in the State of Oaxaca, Mexico

“…Infections by this TcIDom occur mainly in northern South America, Central America, and Mexico. These isolates have been predominantly associated with cases of cardiomyopathy and are more resistant to benznidazole than other genetic groups [ 14 , 34 , 35 ]. In Mexico, it has been shown that isolates obtained in Querétaro and Ninoa belonging to the TcI genotype can invade the digestive system, in addition to causing damage to the heart [ 33 ].…”

“…The TSSA is a 14-kDa surface antigen mainly expressed at the trypomastigote stage, capable of transferring sialic acid from host glycoconjugates to β-galactopyranose residues to parasite mucins, thereby generating a surface negative charge that protects the parasite from the alternate complement pathway and opsonization by antibodies. It is also linked with adhesion and invasion to epithelial, neuronal, and glial cells [ 35 ].…”

“…Proteins of this family are also expressed in epimastigotes to promote their adhesion to endothelial cells, in addition to protecting the parasite from the action of glycolytic enzymes in the vector’s digestive tract. At a transcriptional level, the tssa mRNA can be detected in trypomastigotes, amastigotes, and epimastigotes [ 23 , 35 , 38 ]. In patients with a positive history of parasitemia, the tssa has a good diagnostic potential for the chronic stage of the disease, where it is found in amastigotes [ 39 ].…”