Changes in isotype composition and antigen recognition of anti‐Trypanosoma cruzi antibodies from acute to chronic Chagas disease

Abstract

This report describes differences in humoral immune response of acute and chronic phases of human Chagas disease. The reactivities of IgG, IgM, and IgA anti-Trypanosoma cruzi antibodies in serum samples from both groups of patients were compared by enzyme-linked immunosorbent assay (ELISA) employing either one of four antigenic fractions: mouse laminin (LAM), which reacts through Gal alpha 1-3Gal epitopes expressed on trypomastigote surface: whole intact trypomastigotes (TCT); trypomastigotes excreted/secreted antigens (TESA); and epimastigote alkaline extract (EAE). The selection of T. cruzi antigen preparations was based on their relative content of surface and internal antigens found in trypomastigote forms. The proportion of IgG reactive to carbohydrate epitopes was assessed through the decay of IgG reactivity from acute and chronic sera after m-periodate oxidation of solid-phase bound antigens. Trypomastigote and TESA antigens recognized by IgG from acute and chronic sera were also compared by immunoblotting. ELISA and immunoblotting data showed that: (1) the proportion of IgG directed to trypomastigote surface antigens was higher in acute than in chronic sera, whereas the opposite was found for internal antigens, (2) acute sera contained a higher percentage of IgG reactive to trypomastigote carbohydrate epitopes than chronic sera, and (3) anti-T. cruzi IgA was found exclusively in acute sera and led to 100% positivity when LAM, TCT, and TESA were employed as antigens. IgA ELISA with these antigens and IgG immunoblotting pattern with TESA could be useful as serological markers for the acute phase of human Chagas disease.

Serological diagnosis of Chagas disease with purified and defined Trypanosoma cruzi antigens

“…Antibodies from IgM class first appears as a typical sign of the acute phase of the disease, and there are some reports of an increase of total and specific IgA antibody class at this early phase (Lorca et al 1995, Umezawa et al 1996a. Antibodies of the IgG class, already present in the acute phase, accompanies the infection until the chronic phase.…”

Electrocardiographic findings in Mexican chagasic subjects living in high and low endemic regions of Trypanosoma cruzi infection

“…It is also known that chronic chagasic cardiomyopathy patients display high anti-T. cruzi antibodies even in those infected cases that lived in endemic zones for only short time of their life (Cerban et al 1993, Umezawa et al 1996). This conflicting point deserves further analysis to explain why antibody levels could be different between resident from high and low endemic regions in spite of parasite persistence in both groups.…”

Soroprevalência da infecção por Trypanosoma cruzi em cães de uma área rural do Estado de Mato Grosso do Sul

“…A pesquisa de anticorpos anti-Trypanosoma cruzi por meio do ELISA utilizou um extrato total de formas epimastigotas, conforme descrito previamente (Umezawa 1996) Com o objetivo de confirmar a presença de T. cruzi e de Leishmania spp. na área, quatro cães que atenderam ao crité-rio de positividade para infecção chagásica e não apresentaram anticorpos anti-Leishmania foram submetidos ao xenodiagnóstico clássico, utilizando 30 ninfas de Triatoma infestans e 30 ninfas de T. sordida, e ao exame parasitológico direto para observação de formas amastigotas de Leishmania sp.…”