[Identification of immunodominant components of an isolate of Trypanosoma cruzi by immunoblot and its standardization for diagnostic purposes].

INTRODUCTION Conventional serology was used for the detection of Trypanosoma cruzi infection, with diverse sensitivity and specificity results. Due to the number of samples with doubtful results, it is necessary to develop additional confirmation tests such as the immunoblot. OBJECTIVE The aim of this study was identify major immunogenic proteins of T. cruzi isolate and establish criteria for immunoblot positivity with diagnostic purposes. METHODS Immunoblot initial standardization was performed, determining optimal concentrations of antigen, serum, and second antibody. Thirty-five positive and thirty negative sera were assayed to evaluate different criteria of positivity and determine which provides greater sensitivity and specificity. RESULTS Immunoblot of T. cruzi positive sera shared a rich pattern of components with molecular weights between 10-250 kDa. Twelve components had a recognition rate higher than 50%, of which the polypeptides of 27, 32, 34, and 38 kDa were close to 100%. Of the positivity criteria evaluated, the recognition of the components of 27 and 32 kDa provided sensitivity and specificity of 100%. DISCUSSION The Immunoblot is suitable for confirmation of infection by T. cruzi, so it is strongly recommended for confirmation and discrimination of discordant cases.