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- Title
Accurate Real-Time PCR Strategy for Monitoring Bloodstream Parasitic Loads in Chagas Disease Patients.
- Authors
Duffy, Tomas; Bisio, Margarita; Altcheh, Jaime; Burgos, Juan Miguel; Diez, Mirta; Levin, Mariano Jorge; Favaloro, Roberto Rene; Freilij, Hector; Schijman, Alejandro Gabriel
- Abstract
Background: 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. Methodology/Principal Findings: The Q-PCR has a detection limit of 0.1 and 0.01 parasites/mL, with a dynamic range of 106 and 107 for Silvio X10 cl1 (T. cruzi I) and Cl Brener stocks (T. cruzi IIe), respectively, an efficiency of 99%, and a coefficient of determination (R2) 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. Conclusion/Significance: 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.
- Subjects
POLYMERASE chain reaction; CHAGAS' disease; TRYPANOSOMA cruzi; DNA; PLASMIDS; PARASITES; ANTIPARASITIC agents; IMMUNOSUPPRESSION; HEART diseases; PATIENTS
- Publication
PLoS Neglected Tropical Diseases, 2009, Vol 3, Issue 4, p1
- ISSN
1935-2727
- Publication type
Article
- DOI
10.1371/journal.pntd.0000419