El ensayo inmunoenzimatico en microgotas sobre nitrocelulosa (Dot-ELISA) en el diagnostico de la enfermedad de Chagas: I. Estudio comparativo de dos preparaciones antigenicos de Trypanosoma cruzi

Abstract

Using the Dot-ELISA technique, two antigenic preparations of Trypanosoma cruzi epimastigote forms have been compared for the diagnosis of Chagas' disease: (1) The cytoplasmic fraction (cytoplasmic antigen) and (2) whole formalin fixed epimastigotes (integral antigen). There was been used sera from 95 chagasic patients with chronic cardiomyopathy, positive conventional serology and either positive or negative xenodiagnosis; 74 subjects with negative conventional serology, and either clinically normal or presenting cardiomyopathy; 74 patients with different diseases including syphilis, toxoplasmosis, leishmaniasis or autoantibodies such as rheumatoid factor and antinuclear antibodies. By defining the diagnostic titers (cut off): 1:512 for cytoplasmic antigen and 1:128 for the integral antigen, a sensitivity of 100% has been obtained with both antigenic preparations, being the specificity of 96% for the former and 100% for the latter when leishmaniasis sera were not included. A comparative study with conventional serology was carried out using 147 sera from a Laboratory of Chagas' diagnosis; Dot-ELISA with cytoplasmic antigen showed co-positivity index of 1.0, co-negativity 0.989 and efficiency of 0.993, and Dot-ELISA with integral antigen 1.0, 0.979 and 0.986 respectively. According to this evaluation, Dot-ELISA using whole formalin fixed epimastigotes might be a practical alternative for the serological diagnosis of Chagas' disease.

A reliable and specific enzyme-linked immunosorbent assay for the capture of IgM from human chagasic sera using fixed epimastigotes of Trypanosoma cruzi

“…Recombinant antigens for IgG serology (e.g., B13 antigen), which increase speci®city and have been proposed to be more advantageous than crude extracts of T. cruzi, were not suitable for the capture of speci®c IgM due to the preferential binding of IgM to glycoconjugates such as lipophosphoglycan (LPPG; Umezawa et al 1996). An earlier study had compared the sensitivity and speci®city of an antigenic preparation of T. cruzi epi, and the results pointed to the use of whole ®xed epi (Hubsch et al 1988). We then asked the following simple question: can the conventional antigen applied in iIF serology (®xed epi) also be used for ELISA?…”

“…Epi grow easily in culture media, which represents a rapid way of obtaining plenty of antigen (Hubsch et al 1988). A single step of enzyme-conjugate titration is then required to set up the ELISA.…”

“…In recent infections, Ab have mainly been of the IgM class (Lelchuk et al 1970). Accidental laboratory infections have shown that speci®c IgM can be observed 15 days after T. cruzi inoculation (Grauert et al 1993), and its detection by indirect immuno¯uorescence (iIF) is commonly used as a parameter for assessment of recent infection (Camargo and Amato Neto 1974).…”

Tripanosomiasis americana: determinación de riesgo epidemiológico de transmisión en el municipio de Amalfi, Antioquia

“…En relación con el diagnóstico, está basado en la identificación del parásito en sangre y tejidos, en heces de triatominos por el método del xenodiagnóstico o mediante serologías, para lo cual se han desarrollado varios métodos, tales como inmunofluorescencia indirecta, ELISA, fijación de complemento, hemaglutinación indirecta, aglutinación rápida flagelar, aglutinación directa, etc. (7)(8)(9).…”