Signature patterns and classification of satellite DNA consensus sequences from the 19 <i>T</i>. <i>cruzi</i> stocks analyzed in this work.

<p>Signature patterns and classification of satellite DNA consensus sequences from the 19 <i>T</i>. <i>cruzi</i> stocks analyzed in this work.</p

Description of <i>T</i>. <i>cruzi</i> stocks and satellite DNA sequences analyzed in this work.

<p>Description of <i>T</i>. <i>cruzi</i> stocks and satellite DNA sequences analyzed in this work.</p

Comparative analysis of <i>T</i>. <i>cruzi</i> satellite DNA qPCR sensitivity using cruzi1/cruzi2 and the novel cruzi1c/cruzi2c primers.

<p>Comparative analysis of <i>T</i>. <i>cruzi</i> satellite DNA qPCR sensitivity using cruzi1/cruzi2 and the novel cruzi1c/cruzi2c primers.</p

Genetic distances of satellite DNA sequences between <i>T</i>. <i>cruzi</i> DTUs.

<p>Genetic distances of satellite DNA sequences between <i>T</i>. <i>cruzi</i> DTUs.</p

New insights into <i>Trypanosoma cruzi</i> evolution, genotyping and molecular diagnostics from satellite DNA sequence analysis

<div><p><i>Trypanosoma cruzi</i> has been subdivided into seven Discrete Typing Units (DTUs), TcI-TcVI and Tcbat. Two major evolutionary models have been proposed to explain the origin of hybrid lineages, but while it is widely accepted that TcV and TcVI are the result of genetic exchange between TcII and TcIII strains, the origin of TcIII and TcIV is still a matter of debate. <i>T</i>. <i>cruzi</i> satellite DNA (SatDNA), comprised of 195 bp units organized in tandem repeats, from both TcV and TcVI stocks were found to have SatDNA copies type TcI and TcII; whereas contradictory results were observed for TcIII stocks and no TcIV sequence has been analyzed yet. Herein, we have gone deeper into this matter analyzing 335 distinct SatDNA sequences from 19 <i>T</i>. <i>cruzi</i> stocks representative of DTUs TcI-TcVI for phylogenetic inference. Bayesian phylogenetic tree showed that all sequences were grouped in three major clusters, which corresponded to sequences from DTUs TcI/III, TcII and TcIV; whereas TcV and TcVI stocks had two sets of sequences distributed into TcI/III and TcII clusters. As expected, the lowest genetic distances were found between TcI and TcIII, and between TcV and TcVI sequences; whereas the highest ones were observed between TcII and TcI/III, and among TcIV sequences and those from the remaining DTUs. In addition, signature patterns associated to specific <i>T</i>. <i>cruzi</i> lineages were identified and new primers that improved SatDNA-based qPCR sensitivity were designed. Our findings support the theory that TcIII is not the result of a hybridization event between TcI and TcII, and that TcIV had an independent origin from the other DTUs, contributing to clarifying the evolutionary history of <i>T</i>. <i>cruzi</i> lineages. Moreover, this work opens the possibility of typing samples from Chagas disease patients with low parasitic loads and improving molecular diagnostic methods of <i>T</i>. <i>cruzi</i> infection based on SatDNA sequence amplification.</p></div

Signature patterns of <i>T</i>. <i>cruzi</i> satellite DNA sequences.

<p>Signature patterns of <i>T</i>. <i>cruzi</i> satellite DNA sequences.</p

Signature patterns and classification of satellite DNA consensus sequences from the 19 <i>T</i>. <i>cruzi</i> stocks analyzed in this work.

<p>Signature patterns and classification of satellite DNA consensus sequences from the 19 <i>T</i>. <i>cruzi</i> stocks analyzed in this work.</p

Bayesian phylogenetic tree of 335 satellite DNA sequences from 19 <i>T</i>. <i>cruzi</i> stocks representative of Discrete Typing Units TcI-TcVI.

<p>TcI [Sylvio X10 cl1 (), K-98 (), Col4R (), and Dm28c () stocks], TcII [Y () and JG () stocks], TcIII [3869 (), M6241 cl6 (), and LL051-P24-Ro () stocks], TcIV [4167 (), Am64 (), and Dog Theis () stocks], TcV [115 (), B147 (), and NR cl3 () stocks], and TcVI [CL Brener (), RA (), VD (), and Tulahuen () stocks]. Posterior probability values are shown at nodes for relevant groups.</p

Specimens included in this study.

*<p> = these included three mothers in investigations of possible congenital transmission and four organ donors with chronic Chagas disease. PCR-testing was performed on these chronically infected persons to aid in the evaluation of disease transmission risk.</p

Validation data for the real-time PCR assays.

<p>Validation data for the real-time PCR assays.</p