Epitope mapping of a single repetitive unit of the B13 Trypanosoma cruzi antigen as fusions to Escherichia coli LamB protein

Abstract

B13, one of the immunodominant antigens of Trypanosoma cruzi, is composed of repeats of a 12-amino-acid motif. Using synthetic peptides, the sequence FGQAAAGDK was previously shown to contain the B13 immunodominant epitope recognized by chagasic patients sera. To investigate the effects of neighboring sequences in the immunodominance, we tested serum recognition of two B13 sequences fused to LamB. GDKPSPFGQAAA-LamB and FGQAAAGDKPSP-LamB were recognized, respectively, by 15% and 80% of 80 sera reactive to B13 antigen. Recognition of FGQAAAGDKPSP-LamB was inhibited by AAAGDK-containing synthetic peptides. FGQAAAGDKPSP-LamB competed with a B13 recombinant protein containing 16.6 repeats for binding to chagasic antibodies. These results strengthen previous conclusions on the immunodominant epitope of B13 and provide a comparison of two methods for epitope mapping.

Evidence for T Cell Help in the IgG Response against Tandemly RepetitiveTrypanosoma cruziB13 Protein in Chronic Chagas Disease Patients

“…This has also been reported for a few other recombinant T. cruzi antigens, such as antigens JL5, JL9, and the C-terminal region of T. cruzi HSP70 [27]. B13 and JL5 have been described as cross-reactive with cardiac myosin [28–30] and cardiovascular beta-adrenergic and cholinergic receptors respectively [31]. It is possible that the higher levels displayed in sera from CCC patients of these two potentially pathogenic cross-reactive antibody systems are biologically relevant in the generation of pathological autoimmunity.…”