[Trypanosoma cruzi: solubilization and partial characterization of antigenic components with Triton X-100]

A new antigenic fraction to be used in the immunodiagnostic of Chagas' disease was obtained by treating Trypanosoma cruzi epimastigotes with Triton X-100. The method comprises the following steps: a) Epimastigotes grown in a modified LIT medium were harvested at the initial stage of the stationary phase (cell population near 200 x 10(6)/ml; pH 7) and were centrifuged during 15 min at 2500 rpm., at 4 degrees C. b) The pellet was washed and then resuspended in a medium free of proteins (470 m Osmolar), composed of NaC1, KC1, Na2HPO4 and glucose, (GSM). c) To preserve cell breakage, as well as cell motility and viability, the best relationship between cell population and Triton X-100 concentration was determined (300 x 10(6) cells/ml and 162 microM). Cells were kept at 4 degrees C during 1 h, and vigorously mixed every 10 min. d) Cell suspension was centrifuged during 60 min at 2.500 rpm at 4 degrees C. e) The soluble extract was passed through a 0.22 mu filter Millipore. 0,42 to 0,44 mg proteins/ml were always detected in the recovered supernatant. The sensibility of this proteic fraction (F1) to detect anti-T. cruzi antibodies was studied by the complement-fixation (C'FH50) and the indirect hemagglutination (IHA) tests. The antigen used by the Instituto de Medicina Tropical, from the Universidad Central de Venezuela, M(PM), was employed as reference. The F1 showed a four to eight greater sensibility using the C'FH50 reaction while with IHA test F1 capability to detect antibodies against T. cruzi was eight times greater than the reference antigen. The immunoelectrophoretic analysis of the isolated fraction showed at least five protein components.