Immunoagglutination test to diagnose Chagas disease: comparison of different latex-antigen complexes

Abstract

OBJETIVE To evaluate the diagnostic performance of novel latex–protein complexes obtained from different antigens of Trypanosoma cruzi through immunoagglutination test using a panel of T. cruzipositive sera, leishmaniasis-positive sera and negative sera for both parasites. METHODS Complexes’ behaviour using total parasite homogenate (TPH), two simple recombinant proteins (RP1 and RP5) and two chimeric recombinant proteins (CP1 and CP2) was comparatively evaluated. The area under ROC curves was used as an index of accuracy. Sensitivity, specificity and discrimination efficiency were assessed. RESULTS All recombinant antigens showed higher specificity than TPH. The lower specificity of TPH was mainly due to cross-reacting peptides between T. cruzi and Leishmania spp. In turn, all performance indicators were higher for CP1 and CP2 than for RP1 and RP5. The carboxylated latex– CP2 (C2–CP2) complex was able to detect antibodies against T. cruzi. The values of area under ROC curve (0.96), sensitivity (92.3%, 95% CI: 79.4–100.0%) and specificity (84.0%, 95% CI: 67.6– 100.0%) indicate that the assay could be used as a screening test. conclusion The C2–CP2 complex could be an important tool to carry out sero-epidemiological studies.