Fine mapping of Trypanosoma cruzi epitopes using high-density peptide chips: alanine and length scans

BRACCO L; BUSCAGLIA CA; ALTCHEH J; AGÜERO F

Resistencia, Chaco

Congreso; XXX Reunión de la Sociedad Argentina de Protozoologia y Enfermedades Parasitarias; 2018

Sociedad Argentina de Protozoologia y Enfermedades Parasitarias

Chagas Disease is a major health problem in America for which no vaccine for large-scale public healthinterventions are yet available. Accurate diagnosis is essential for the early identification, follow up and pre-vent non-vector transmission. Diagnosis is routinely performed using serological methods, which require wellcharacterized antigens. Although available tests give satisfactory results, the production of reliable reagentsremains laborious and expensive. We have conducted a large-scale screening of T. cruzi linear B-cell epitopesusing high-density peptide chips, leading to the identification of 200 novel antigens. Based on these resultswe have developed a multiepitope diagnostic test that have excellent diagnostic performance (Mucci J, etal 2017). For each epitope, understanding which residues are important for antibody binding can lead toimproved diagnostic reagents. For example, this may help identify if these key residues are conserved inother T. cruzi sequenced strains and isolates. To obtain improve the serological characterization of knownantigens, we performed a number of epitope-mapping experiments using high-density peptide arrays. First,we performed Alanine scans for 276 different protein antigens (506 antibody-binding peaks/epitopes) thathad been reactive in at least one of several peptide chip assays. This experiment is based on permutingan alanine in each position of the sequence to be studied, hence assessing the impact of replacing eachoriginal amino acid on the reactivity of each peptide sequence. Secondly, we performed a length scan onselected peptides, to analyze how the length of an epitope-containing peptide may affect the antibody-binding in these assays. For this, we have performed complete length scans of the C-terminal portion of 58proteins belonging to the trans-sialidase super family of T. cruzi antigens. This length scan was performedby scanning these sequences with peptides of lengths 7 to 18. This work led to the identification of preciseresidue positions in epitopes that play a fundamental role in the seroreactivity of the corresponding antigens.