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The physical adsorption and the chemical coupling of recombinant proteins of Trypanosoma cruzi onto polystyrene and core-shell carboxylated particles were respectively investigated with the ultimate aim of producing latex-protein complexes to be used in an immunoagglutination assay able to detect the Chagas disease. To this effect, two single proteins (RP1 and RP5) and a multiepitope protein derived from three antigenic peptides (CP2) were evaluated, and sensitizations were carried out at different pHs. The maximum physical adsorption was produced at pHs close to the protein isoelectric point (i.e., pH 6 for RP5 and pH 5 for RP1 and CP2). High fractions of antigens were chemically bound to the carboxyl groups, and the highest surface density of linked protein was also observed at pHs close to the protein isoelectric point. The three latex-protein complexes obtained by covalent coupling at such pHs were tested with sera from a panel of 16 infected and 16 non-infected patients. In the immunoagglutination assays, the latex-CP2 complex produced the best discrimination between positive and negative sera., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Objective 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. cruzi-positive 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. [ABSTRACT FROM AUTHOR]

Abstract: This article describes the physical adsorption and the chemical coupling of 3 antigenic proteins of Trypanosoma cruzi onto polystyrene (PS) based latexes to be used as novel immunodiagnosis reagents for detecting the Chagas disease. The coupled proteins were a homogenate of T. cruzi, or a recombinant protein (either Ag36 or CP1). With the homogenate, between 30 and 60% of the total-linked protein was chemically coupled, showing a small dependence with the pH. For Ag36 and CP1, around 90% of the total-linked protein was chemically coupled, with a maximum coupling at pH 5 (i.e., close to the isoelectric point). The chemical coupling of CP1 was less affected by the pH than the coupling of Ag36. [Copyright &y& Elsevier]