International study to evaluate PCR methods for detection of Trypanosoma cruzi DNA in blood samples from Chagas disease patients

A century after its discovery, Chagas disease, caused by the parasite Trypanosoma cruzi, still represents a major neglected tropical threat. Accurate diagnostics tools as well as surrogate markers of parasitological response to treatment are research priorities in the field. The polymerase chain reaction (PCR) has been proposed as a sensitive laboratory tool for detection of T. cruzi infection and monitoring of parasitological treatment outcome. However, high variation in accuracy and lack of international quality controls has precluded reliable applications in the clinical practice and comparisons of data among cohorts and geographical regions. In an effort towards harmonization of PCR strategies, 26 expert laboratories from 16 countries evaluated their current PCR procedures against sets of control samples, composed by serial dilutions of T.cruzi DNA from culture stocks belonging to different lineages, human blood spiked with parasite cells and blood samples from Chagas disease patients. A high variability in sensitivities and specificities was found among the 48 reported PCR tests. Out of them, four tests with best performance were selected and further evaluated. This study represents a crucial first step towards device of a standardized operative procedure for T. cruzi PCR.Fil: Schijman, Alejandro G. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI-CONICET). Laboratorio de Biología Molecular de la Enfermedad de Chagas (LabMECh); Argentina.Fil: Bisio, Margarita. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI-CONICET). Laboratorio de Biología Molecular de la Enfermedad de Chagas (LabMECh); Argentina.Fil: Orellana, Liliana. Universidad de Buenos Aires. Instituto de Cálculo; Argentina.Fil: Sued, Mariela. Universidad de Buenos Aires. Instituto de Cálculo; Argentina.Fil: Duffy, Tomás. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI-CONICET). Laboratorio de Biología Molecular de la Enfermedad de Chagas (LabMECh); Argentina.Fil: Mejia Jaramillo, Ana M. Universidad de Antioquia. Grupo Chagas; Colombia.Fil: Cura, Carolina. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI-CONICET). Laboratorio de Biología Molecular de la Enfermedad de Chagas (LabMECh); Argentina.Fil: Auter, Frederic. French Blood Services; Francia.Fil: Veron, Vincent. Universidad de Parasitología. Laboratorio Hospitalario; Guayana Francesa.Fil: Qvarnstrom, Yvonne. Centers for Disease Control. Department of Parasitic Diseases; Estados Unidos.Fil: Deborggraeve, Stijn. Institute of Tropical Medicine; Bélgica.Fil: Hijar, Gisely. Instituto Nacional de Salud; Perú.Fil: Zulantay, Inés. Facultad de Medicina; Chile.Fil: Lucero, Raúl Horacio. Universidad Nacional del Nordeste; Argentina.Fil: Velázquez, Elsa. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Parasitología Dr. Mario Fatala Chaben; Argentina.Fil: Tellez, Tatiana. Universidad Mayor de San Simon. Centro Universitario de Medicina Tropical; Bolivia.Fil: Sanchez Leon, Zunilda. Universidad Nacional de Asunción. Instituto de Investigaciones en Ciencias de la Salud; Paraguay.Fil: Galvão, Lucia. Faculdade de Farmácia; Brasil.Fil: Nolder, Debbie. Hospital for Tropical Diseases. London School of Tropical Medicine and Hygiene Department of Clinical Parasitology; Reino Unido.Fil: Monje Rumi, María. Universidad Nacional de Salta. Laboratorio de Patología Experimental; Argentina.Fil: Levi, José E. Hospital Sirio Libanês. Blood Bank; Brasil.Fil: Ramirez, Juan D. Universidad de los Andes. Centro de Investigaciones en Microbiología y Parasitología Tropical; Colombia.Fil: Zorrilla, Pilar. Instituto Pasteur; Uruguay.Fil: Flores, María. Instituto de Salud Carlos III. Centro de Mahahonda; España.Fil: Jercic, Maria I. Instituto Nacional De Salud. Sección Parasitología; Chile.Fil: Crisante, Gladys. Universidad de los Andes. Centro de Investigaciones Parasitológicas J.F. Torrealba; Venezuela.Fil: Añez, Néstor. Universidad de los Andes. Centro de Investigaciones Parasitológicas J.F. Torrealba; Venezuela.Fil: De Castro, Ana M. Universidade Federal de Goiás. Instituto de Patologia Tropical e Saúde Pública (IPTSP); Brasil.Fil: Gonzalez, Clara I. Universidad Industrial de Santander. Grupo de Inmunología y Epidemiología Molecular (GIEM); Colombia.Fil: Acosta Viana, Karla. Universidad Autónoma de Yucatán. Departamento de Biomedicina de Enfermedades Infecciosas y Parasitarias Laboratorio de Biología Celular; México.Fil: Yachelini, Pedro. Universidad Católica de Santiago del Estero. Instituto de Biomedicina; Argentina.Fil: Torrico, Faustino. Universidad Mayor de San Simon. Centro Universitario de Medicina Tropical; Bolivia.Fil: Robello, Carlos. Instituto Pasteur; Uruguay.Fil: Diosque, Patricio. Universidad Nacional de Salta. Laboratorio de Patología Experimental; Argentina.Fil: Triana Chavez, Omar. Universidad de Antioquia. Grupo Chagas; Colombia.Fil: Aznar, Christine. Universidad de Parasitología. Laboratorio Hospitalario; Guayana Francesa.Fil: Russomando, Graciela. Universidad Nacional de Asunción. Instituto de Investigaciones en Ciencias de la Salud; Paraguay.Fil: Büscher, Philippe. Institute of Tropical Medicine; Bélgica.Fil: Assal, Azzedine. French Blood Services; Francia.Fil: Guhl, Felipe. Universidad de los Andes. Centro de Investigaciones en Microbiología y Parasitología Tropical; Colombia.Fil: Sosa Estani, Sergio. ANLIS Dr.C.G.Malbrán. Centro Nacional de Diagnóstico e Investigación en Endemo-Epidemias; Argentina.Fil: DaSilva, Alexandre. Centers for Disease Control. Department of Parasitic Diseases; Estados Unidos.Fil: Britto, Constança. Instituto Oswaldo Cruz/FIOCRUZ. Laboratório de Biologia Molecular e Doenças Endêmicas; Brasil.Fil: Luquetti, Alejandro. Laboratório de Pesquisa de Doença de Chagas; Brasil.Fil: Ladzins, Janis. World Health Organization (WHO). Special Programme for Research and Training in Tropical Diseases (TDR); Suiza

International Study to Evaluate PCR Methods for Detection of Trypanosoma cruzi DNA in Blood Samples from Chagas Disease Patients

A century after its discovery, Chagas disease, caused by the parasite Trypanosoma cruzi, still represents a major neglected tropical threat. Accurate diagnostics tools as well as surrogate markers of parasitological response to treatment are research priorities in the field. The polymerase chain reaction (PCR) has been proposed as a sensitive laboratory tool for detection of T. cruzi infection and monitoring of parasitological treatment outcome. However, high variation in accuracy and lack of international quality controls has precluded reliable applications in the clinical practice and comparisons of data among cohorts and geographical regions. In an effort towards harmonization of PCR strategies, 26 expert laboratories from 16 countries evaluated their current PCR procedures against sets of control samples, composed by serial dilutions of T.cruzi DNA from culture stocks belonging to different lineages, human blood spiked with parasite cells and blood samples from Chagas disease patients. A high variability in sensitivities and specificities was found among the 48 reported PCR tests. Out of them, four tests with best performance were selected and further evaluated. This study represents a crucial first step towards device of a standardized operative procedure for T. cruzi PCR

Performances of PCR tests in Sets A and B.

<p>LbX/1-6, Laboratory and test identification; Bold Type, Good Performing Methods in sets A or B; GPM, Good Performing Methods in sets A and B; Sp, 100% of specificity in all controls without <i>T. cruzi</i> DNA; Co, Coherence in PCR positive reports; DL, Detection limit in fg DNA/ul; Y, Affirmative; N, Negative; NA, Not available; ND, Not detectable<b>.</b></p

Intra-Laboratory Evaluation of the four Best Performing Methods in samples from Table 5.

<p>LbX/1−6, Laboratory and test identification; Se, sensitivity; Sp, specificity; Acc, accuracy; kappa, kappa index.</p

Intra-laboratory evaluation of best performing methods in human samples.

<p>ID, sample identification number; LbX/1-6, Laboratory and test identification; % pos, Percentage of Positivity; Cons, Consensus PCR Result; pos, positive; neg, negative.</p

Concordance of PCR results reported for each clinical case of Set C.

<p>Patients 1 to 32 are seropositive and 33 to 42 seronegative. 28 kDNA tests and 13 Sat DNA tests were performed for each sample.</p><p>kDNA, minicircle DNA; Sat-DNA, satellite DNA; GPM Good performing Methods in panels A and B; ID, sample identification number; G, Gender; Ag, age in years; EN, Endemic precedence; %: Percentage of positive results; Cons, Consensus PCR result; F, female; M, male; NA, not available; 28 kDNA tests and 13 Sat DNA tests were performed for each sample.</p>1<p><i>T.cruzi</i> DTU I,</p>2<p><i>T.cruzi</i> DTU II/V/VI, NE, not endemic; Uk, Unknown; Pos, positive consensus; Ind, indeterminate consensus; Neg, negative consensus; cChHD, chronic Chagas heart disease, Mega Megacolon, CBBB, Complete Branch Bundle Blockage, HTx, Heart transplantation; Arg: Argentina; Bo: Bolivia; Br: Brazil; Par: Paraguay; BAs, Buenos Aires; Bh, Bahia; Go, Goias; MG: Minas Gerais; Sg: Santiago del Estero.</p

Performance of PCR tests in comparison to consensus GPM reports and serodiagnosis.

<p>LbX/1-6, Laboratory and test identification; BPM, Best Performing Methods; Consensus GPM K + S: consensus findings of GPM by kDNA and Satellite DNA PCRs; C, Conventional PCR, RT, Real Time PCR; K, kDNA; S, Satellite DNA; Se, sensitivity; Sp, specificity; Acc, accuracy; kappa, kappa index; N, negative; Y, affirmative; 25–75p, 25th-75th percentiles; Bold type, Good Performing Methods (GPM) in sets A and B.</p

Examples of the outputs of the four best performing PCR methods.

<p>A. LbD2 ; B.LbD3, C. LbF1 and D. LbQ. The methods are described in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0000931#s2" target="_blank">Materials and Methods</a> and <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0000931#pntd-0000931-t001" target="_blank">Table 1</a>. 6, 15: seropositive samples; 35; seronegative sample (<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0000931#pntd-0000931-t003" target="_blank">Table 3</a>). PC: Positive control: 10 fg/µl of T.cruzi VI. NC. Negative Control: Master Mixes devoid of DNA.</p

Analytical Sensitivity of specific and coherent PCR tests in sets A and B.

<p>Distribution of detection limits (DL) of specific and coherent PCR tests targeted to Sat-DNA (A) and kDNA sequences (B) for detecting serial dilutions of purified DNA from 3 parasite stocks (Set A) representative of <i>T. cruzi</i> DTU I (Silvio×10), DTU IV (Can III cl1) and DTU VI (Cl Brener). C. Distribution of detection limits (DL) of specific and coherent PCR tests targeted to Sat-DNA (black bars) and kDNA sequences (white bars) carried out from human blood spiked with serial dilutions of parasite cells (Set B).</p