Evaluation of Trypanosoma cruzi antigens for the indirect hemagglutination test: II. Different stocks and evolutive forms

Abstract

To improve sensitivity and specificity of the indirect hemagglutination test (IHA) for Chagas' disease serodiagnosis, different antigens of Trypanosoma cruzi extracts from epimastigotes (A1.7, B12 and CI clones; Y and D150 strains) and from trypomastigotes (metacyclics and tissue cell cultures) -were tested. Sera of 132 individuals with chronic Chagas' disease, demonstrated by immunofluorescence test (IFT) and sera of 161 non chagasic individuals were assayed. The IFT was the reference test to evaluate the co-positivity index (c.p.i.) and co-negativity index (c.ni.). The antigens of Y strain and B12 clone presented high values for the calculated index with a cut off of 1:40, suggesting sensitivity, specificity and agreement of IHA in relation to IFT. Antigens of A1.7 and CI clones presented high values for the calculated index only with a cut off of 1:80. Titers presented by sera from chagasics tested by IHA with trypomastigote antigens were lower than those with epimastigote antigens. Trypomastigote antigens gave lower values for co-positivity index, suggesting little sensitivity in relation to IFT.