Accurate real-time PCR strategy for monitoring bloodstream parasitic loads in chagas disease patients.

<h4>Background</h4>This report describes a real-time PCR (Q-PCR) strategy to quantify Trypanosoma cruzi (T. cruzi) DNA in peripheral blood samples from Chagas disease patients targeted to conserved motifs within the repetitive satellite sequence.<h4>Methodology/principal findings&l...

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Autores principales: Tomas Duffy, Margarita Bisio, Jaime Altcheh, Juan Miguel Burgos, Mirta Diez, Mariano Jorge Levin, Roberto Rene Favaloro, Hector Freilij, Alejandro Gabriel Schijman
Formato: article
Lenguaje:EN
Publicado: Public Library of Science (PLoS) 2009
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Acceso en línea:https://doaj.org/article/5f7dacb14bf04d5099766327b89ba849
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Sumario:<h4>Background</h4>This report describes a real-time PCR (Q-PCR) strategy to quantify Trypanosoma cruzi (T. cruzi) DNA in peripheral blood samples from Chagas disease patients targeted to conserved motifs within the repetitive satellite sequence.<h4>Methodology/principal findings</h4>The Q-PCR has a detection limit of 0.1 and 0.01 parasites/mL, with a dynamic range of 10(6) and 10(7) for Silvio X10 cl1 (T. cruzi I) and Cl Brener stocks (T. cruzi IIe), respectively, an efficiency of 99%, and a coefficient of determination (R(2)) of 0.998. In order to express accurately the parasitic loads: (1) we adapted a commercial kit based on silica-membrane technology to enable efficient processing of Guanidine Hydrochloride-EDTA treated blood samples and minimize PCR inhibition; (2) results were normalized incorporating a linearized plasmid as an internal standard of the whole procedure; and (3) a correction factor according to the representativity of satellite sequences in each parasite lineage group was determined using a modified real-time PCR protocol (Lg-PCR). The Q-PCR strategy was applied (1) to estimate basal parasite loads in 43 pediatric Chagas disease patients, (2) to follow-up 38 of them receiving treatment with benznidazole, and (3) to monitor three chronic Chagas heart disease patients who underwent heart-transplantation and displayed events of clinical reactivation due to immunosupression.<h4>Conclusion/significance</h4>All together, the high analytical sensitivity of the Q-PCR strategy, the low levels of intra- and inter-assay variations, as well as the accuracy provided by the Lg-PCR based correction factor support this methodology as a key laboratory tool for monitoring clinical reactivation and etiological treatment outcome in Chagas disease patients.