RESUMO
The diagnosis of visceral leishmaniasis (VL), a serious and often fatal parasitic disease caused by members of the Leishmania donovani complex, remains problematic. Current methods rely on clinical criteria, parasite identification in aspirate material, and serology. The latter methods use crude antigen preparations lacking in specificity. A previously described cloned antigen, rK39, of Leishmania specific for all members of the L. donovani complex (L. chagasi, L. donovani, L. infantum) was very useful in the serodiagnosis by ELISA of both human and canine VL. The present study demonstrated that rK39 seroreactivity correlated with active disease. The sera from early or self-healing infected subjects reacted with leishmanial lysate and were generally nonreactive with rK39. These data demonstrate the utility of rK39 in the serodiagnosis of VL and as an indicator of active disease.
Assuntos
Anticorpos Antiprotozoários/sangue , Antígenos de Protozoários , Leishmania infantum/imunologia , Leishmaniose Visceral/diagnóstico , Leishmaniose Visceral/imunologia , Proteínas de Protozoários/imunologia , Animais , Especificidade de Anticorpos , Antígenos de Protozoários/genética , Biomarcadores , Brasil/epidemiologia , Criança , Clonagem Molecular , Reações Cruzadas , Cães , Ensaio de Imunoadsorção Enzimática , Humanos , Leishmania infantum/genética , Leishmaniose Visceral/epidemiologia , Proteínas de Protozoários/genética , Testes SorológicosRESUMO
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.