Abstract
BackgroundTrypanosoma cruzi, the etiologic agent of Chagas disease, is currently divided into six discrete typing units (DTUs), named TcI-TcVI. TcII is among the major DTUs enrolled in human infections in South America southern cone, where it is associated with severe cardiac and digestive symptoms. Despite the importance of TcII in Chagas disease epidemiology and pathology, so far, no genome-wide comparisons of the mitochondrial and nuclear genomes of TcII field isolates have been performed to track the variability and evolution of this DTU in endemic regions.ResultsIn the present work, we have sequenced and compared the whole nuclear and mitochondrial genomes of seven TcII strains isolated from chagasic patients from the central and northeastern regions of Minas Gerais, Brazil, revealing an extensive genetic variability within this DTU. A comparison of the phylogeny based on the nuclear or mitochondrial genomes revealed that the majority of branches were shared by both sequences. The subtle divergences in the branches are probably consequence of mitochondrial introgression events between TcII strains. Two T. cruzi strains isolated from patients living in the central region of Minas Gerais, S15 and S162a, were clustered in the nuclear and mitochondrial phylogeny analysis. These two strains were isolated from the other five by the Espinhaço Mountains, a geographic barrier that could have restricted the traffic of insect vectors during T. cruzi evolution in the Minas Gerais state. Finally, the presence of aneuploidies was evaluated, revealing that all seven TcII strains have a different pattern of chromosomal duplication/loss.ConclusionsAnalysis of genomic variability and aneuploidies suggests that there is significant genomic variability within Minas Gerais TcII strains, which could be exploited by the parasite to allow rapid selection of favorable phenotypes. Also, the aneuploidy patterns vary among T. cruzi strains and does not correlate with the nuclear phylogeny, suggesting that chromosomal duplication/loss are recent and frequent events in the parasite evolution.
Highlights
Trypanosoma cruzi, the etiologic agent of Chagas disease, is currently divided into six discrete typing units (DTUs), named T. cruzi strains Sylvio (TcI)-TcVI
T. cruzi nuclear and mitochondrial phylogeny From a total of 1,563 nuclear single copy genes that are conserved among the CL Brener Esmeraldo and Non-Esmeraldo-like haplotypes [28], 794 were partially de novo assembled in all seven TcII field isolates (Additional file 2: Table S2), while the other 769 genes were absent in at least one of the assemblies
Concerning the TcII field isolates, two pair of samples, S15-S162a and S11-S92a, which were isolated from close geographic regions, were clustered in the phylogenetic analysis, suggesting that for these isolates, genomic diversity correlates with geographic distances
Summary
Trypanosoma cruzi, the etiologic agent of Chagas disease, is currently divided into six discrete typing units (DTUs), named TcI-TcVI. From the six DTUs, TcI, TcII, TcV and TcVI are usually involved with the domestic cycle of Chagas disease, accounting for the majority of the human infections [5]. The division in six DTUs is well accepted, there are four major proposed models to explain T. cruzi evolutionary history [11,12,13,14] Even though these models disagree about the ancestral strains and the number of hybridization events during T. cruzi evolution, they all agree that TcV and TcVI are hybrids, originated from parental TcII and TcIII strains. Molecular dating suggests that these two hybrid lineages evolved recently; reinforcing the assumption that genetic exchange could still be driving the emergence of T. cruzi recombinant isolates [15, 16]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
