RESUMO
An enzyme-linked immunosorbent assay (ELISA) was developed for detecting antibodies against Trypanosoma cruzi. Two synthetic T. cruzi peptides, TcD and PEP2, were used. The specificity and sensitivity of the peptide ELISA were determined with 260 serum samples from individuals living in an area in which Chagas' disease is endemic. ELISAs were performed with the peptides singly or in combination. The evaluation of these tests showed that 168 (93.8%) of 179 serum samples from T. cruzi-infected patients were positive when TcD peptide was used as antigen; 164 (91.6%) samples were positive with PEP2, and 178 (99.4%) samples were positive when the two peptides were combined. Thus, the sensitivity of the ELISA using the two peptides exceeded 99%. The specificity was evaluated by using a panel of 118 serum samples that included samples from 81 individuals living in an area of endemicity with negative serology for Chagas' disease and from 37 patients from areas in which T. cruzi was not endemic but with other pathologies, such as leishmaniasis, tuberculosis, and leprosy. Only two false-positive serum samples were found in this group of individuals, giving a test specificity of more than 98%. Because these peptides can be synthesized and are very stable at room temperature, the use of such reagents can improve the standardization and reproducibility of ELISAs for the serodiagnosis of T. cruzi infection.
Assuntos
Antígenos de Protozoários , Doença de Chagas/diagnóstico , Ensaio de Imunoadsorção Enzimática/métodos , Testes Sorológicos/métodos , Sequência de Aminoácidos , Animais , Anticorpos Antiprotozoários/sangue , Antígenos de Protozoários/genética , Doença de Chagas/imunologia , Doença de Chagas/parasitologia , Ensaio de Imunoadsorção Enzimática/estatística & dados numéricos , Estudos de Avaliação como Assunto , Reações Falso-Positivas , Humanos , Dados de Sequência Molecular , Peptídeos/síntese química , Peptídeos/genética , Peptídeos/imunologia , Sensibilidade e Especificidade , Testes Sorológicos/estatística & dados numéricos , Trypanosoma cruzi/genética , Trypanosoma cruzi/imunologiaRESUMO
We have developed an immunodot assay for the serodiagnosis of active visceral leishmaniasis (AVL) which utilizes protein A colloidal gold as the visualizing agent. The test is simple, requires few reagents, and can be completed in two hours. It is sensitive and specific for active visceral leishmaniasis, and generally correlates with the ELISA. Either whole blood or sera in minute quantities may be used as test antibody. In addition, the use of the protein A gold immunodot is shown to detect anti-leishmania antibodies in infected dogs.