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Abstract: Six chimeric synthetic peptides (QCha-1, QCha-2, QCha-3, QCha-4, QCha-5, and QCha-6) incorporating antigenic sequences of two immunodominant repeat B-cell epitopes of Trypanosoma cruzi were synthesized by conventional solid-phase peptide synthesis. The antigenic activity of these peptides was evaluated by UltramicroEnzyme-linked immunosorbent assay (UMELISA) by using panels of positive Chagasic sera (n =82), while specificity was evaluated with samples from healthy blood donors (n =44) and patients with other infectious diseases (n =86). The antigenicity of the chimeric peptides in solid-phase immunoassays was compared with that of the monomeric peptides. Data demonstrated that the chimeric peptide QCha-5 was the most reactive because it detected antibodies to parasite efficiently. The results indicate that chimeric peptide as coating antigen is very useful for the immunodiagnosis of Chagas’ disease. [Copyright &y& Elsevier]

Abstract: Four chimeric synthetic peptides (Q5, Q6, Q7⊗, and Q8⊗), incorporating immunodominant epitopes of the core p19 (105–124a.a.) and envelope gp46 proteins (175–205a.a.), of HTLV-I were obtained. Also, two gp46 monomeric peptides M4 and M5⊗ (Ser at position 192) were synthesized. The analysis of the influence of the peptide lengths and the proline to serine substitution on the chimeric and monomeric peptides’ antigenicity, with regard to the chimeric peptides Q1, Q2, Q3⊗, and Q4⊗, reported previously, for HTLV-I was carried out. The peptides’ antigenicity was evaluated in an ultramicroenzyme-linked immunosorbent assay (UMELISA) using sera of HTLV-I/II. The peptides’ antigenicity was affected appreciably by the change of the peptide length and amino acid substitutions into the immunodominant sequence of gp46 peptide. [Copyright &y& Elsevier]