INTRODUCTION AND OBJETIVES

Chagas’ disease diagnosis: a rapid lateral chromatographic assay using recombinant proteins of Trypanosoma cruzi

  1Andrea Racca, 2Sebastian Marechal, 2Dominique Zeluz, 2Thierry Paper, 1Ivan Marcipar1Laboratorio de Tecnología Inmunológica. FBCB. UNL. 2Biosynex Estrasburgo, Francia

INTRODUCTION AND OBJETIVES

Chagas’ disease is an infection caused by the parasite Trypanosoma cruzi, mainly occurring in Latin American countries where the parasite vector bug, Triatoma infestans, is widespread. The aim of this work was to evaluate a rapid immunochromatographic assay in development for detection of antibody to T. cruzi: Immunoquick Chagas test (Biosynex, France). This rapid test performance was compared with OPERON Chagas Test, an immunochromatographic assay commercially available.

Reithinger, R. et al. Rapid Detection of Trypanosoma cruzi in Human Serum by Use of an Immunochromatographic Dipstick Test. J Clin Microbiol. 2010 Aug;48(8):3003-7Barfield, C.A. et al. A Highly Sensitive Rapid Diagnostic Test for C hagas Disease That Utilizes a Recombinant Trypanosoma cruzi Antigen. IEEE Trans Biomed Eng. 2011 Mar;58(3):814-7.

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MATERIALS AND METHODS

RESULTS

We evaluated serum samples from T. cruzi-infected patients (n =100) which were obtained from the Regional Hospital of Reconquista (Santa Fe, Argentina). Chagas’ disease-negative serum samples without other reactivity (n =102) were obtained from donors from the same hospital. Conventional assays, commercial ELISA and IHA from Wiener Lab (Argentina), were used for diagnostic classification and served for comparison for both rapid tests.

Biosynex´s immunochromatographic is composed of an absorbent pad, a nitrocellulose membrane striped with a control line reagent, a test line reagent with chimeric recombinant T. cruzi antigens and a conjugate pad that contains dried detector reagent. The assay uses 10µl of non diluted samples and a drop rof buffer (Figure 1 and 2). Results are read after 15 min.

Table 1: Performance of two rapid tests

Figure 3: Four negative test results are shown.

CONCLUSIONS

Figure 4: Four positive test results are shown.

Negative tests display one band

corresponding to interassay control line

Positive results display an extra band

corresponding to the specific recombinant T.

cruzi antigen.

Figure 5: Four weak positive test results are shown.

Convencional serology*

Immunoquick Chagas Test Operon Chagas Test

Positive Negative Positive NegativePositive(100) 99 1 95 5

Negative(102) 8 94 4 98

Sensitivity 99,0% 95,0%Specificity 92,2% 96,0%* Convencional serology was performed with a lysate-based ELISA and IHA. Positive and negative

specimens were concordant for both assays.

The high sensitivity obtained with Immunoquick Chagas Test in this preliminary evaluation, indicates that the Biosynex assay has great potential as a new rapid assay for screening purposes.

Figure 1

Figure 2