SERODIAGNOSIS OF CHAGAS-DISEASE BY ENZYME-LINKED-IMMUNOSORBENT-ASSAY USING 2 SYNTHETIC PEPTIDES AS ANTIGENS

An enzyme-linked immunosorbent assay (ELISA) was developed for detecti ng antibodies against Trypanosoma cruzi. Two synthetic T. cruzi peptid es, TcD and PEP2, were used. The specificity and sensitivity of the pe ptide ELISA were determined with 260 serum samples from individuals li ving in an area in which Chagas' disease is endemic. ELISAs were perfo rmed with the peptides singly or in combination. The evaluation of the se tests showed that 168 (93.8%) of 179 serum samples from T. cruzi-in fected patients were positive when TcD peptide was used as antigen; 16 4 (91.6%) samples were positive with PEP2, and 178 (99.4%) samples wer e 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 sero logy for Chagas' disease and from 37 patients from areas in which T. c ruzi was not endemic but with other pathologies, such as leishmaniasis , tuberculosis, and leprosy. Only two false-positive serum samples wer e found in this group of individuals, giving a test specificity of mor e than 98%. Because these peptides can be synthesized and are very sta ble at room temperature, the use of such reagents can improve the stan dardization and reproducibility of ELISAs for the serodiagnosis of T. cruzi infection.