EVALUATION OF AN IMMUNOAGGLUTINATION ASSAY FOR THE DIAGNOSIS OF TRYPANOSOMA CRUZI INFECTION

VALERIA S. GARCIA; VERÓNICA D.G. GONZALEZ; JORGE R. VEGA; IVAN S. MARCIPAR; LUIS M. GUGLIOTTA

Costa Rica

Simposio; XII Simposio Latinoamericano de Polímeros; 2010

Immunodiagnosis latex-protein complexes are useful for detecting pregnancies, rheumatoid arthritis, toxoplasmosis, malaria, brucelosis, and leptospirosis. Immunodiagnosis tests involve specific reactions between an antigen (or antibody) contained in a human fluid and an antibody (or antigen) contained in the latex-protein complex. The particle agglutination process can be visualized either directly or via instrumental methods, such as turbidimetry (T), nephelometry, and light scattering. By using an appropriate equipment, an accurate and sensitive assay is achieved, which can also be automated. Sensitivity and accuracy of the immunoassay depends on the method used to detect the agglutination. This test is claimed to be the quickest and easiest method. Biomolecules are attached onto latex particles either by simple physical adsorption (PA) or by covalent coupling (CC). The latex-protein complexes obtained by PA have low stability and can give unspecified agglutinations. Moreover, the complexes are considered of low quality, due to the potential desorption and denaturalization of the adsorbed proteins. For the chemical coupling of proteins, hydrophilic functionalized latexes of uniform particle size are used. Their hydrophilic nature increases the stability of the latex-protein complexes, and it also prevents nonspecific latex-protein interactions. The production of an immunoagglutination kit can be divided into 4 stages: I) the controlled synthesis of latex particles; II) the surface and size characterization of the latex particles; III) the sensitization of particles with the antigenic protein; and IV) the application of the latex-protein complex in immunoagglutination assays. In this work, the sensitization and application results of latex-protein complexes for detecting anti-T. cruzi IgG in human sera are presented.