CONICET | Buscador de Institutos y Recursos Humanos

Introduction. During an infection, the immune system produces antibodies againstpathogens. With time, the immune repertoires of infected individuals become specificto the history of infections and thus represent a rich source of diagnostic markers.Although the molecular mechanisms that produce extremely large antibodyrepertoires are precisely understood, a comprehensive description of the specificitiesof the global antibody repertoire generated by different infected individuals has beenhindered by the lack of powerful tools. In Chagas Disease the host immune responseis directed to Trypanosoma cruzi, a protozoan parasite that evades immunemediated elimination and mounts long-lasting chronic infections. Although availablediagnostic tests give satisfactory results in most cases, there is currently no goldstandard for diagnosis of infection and discordant results remain a possible cause ofundetected cases. Methods. Here, using state of the art high-density peptide arrayswe examined the global human antibody repertoire developed by Chagas Diseasepatients. We designed peptide arrays to display 2.8 million unique peptides from thecomplete proteomes of T. cruzi strains CL-Brener (hybrid DTU TcVI, 19,668 proteins)and Sylvio X10 (DTU TcI, 10,832 proteins). These were assayed with 72 serumsamples from infected subjects from Argentina, Bolivia, Brazil, Colombia, Mexico andthe US, as well as negative samples from the same regions. A cascading screeningstrategy was designed to first identify the antigenic core of these genomes usingpooled samples. Then, in a secondary screening we assayed individual sera against~ 400,000 peptides derived from the first screening and containing additionalsequence variants from the Tc231 proteome (DTU TcIII). This allowed us to study theseroprevalence of identified antigens and fine map all epitopes. Results. Ouranalysis uncovered >4,500 antigens and >22,000 antibody-binding peaks (epitopes)across all samples, delineating both public (shared) Chagas antigens as well asprivate (non-shared) individual anti-T. cruzi responses. Conclusions. To ourknowledge, this the first and largest collection of Chagas Disease antigens andepitopes described to date. This dataset will enable the study of the human antibodyrepertoire in Chagas Disease at an unprecedented depth and granularity, while alsoproviding a rich dataset of serological biomarkers.