Next-Generation Immunoassay Developed for Chagas Diseases

Chagas disease, caused by the protozoan Trypanosoma cruzi, is a major health and economic problem in Latin America for which no vaccine or appropriate drugs for large-scale public health interventions are yet available.

Accurate diagnosis is essential for the early identification and follows up of vector-borne cases and to prevent transmission of the disease by way of blood transfusions and organ transplantation. Diagnosis is routinely performed using serological methods, some of which require the laborious production of parasite lysates, parasite antigenic fractions or purified recombinant antigens.

Medical Parasitologists at the National University of General San Martín (Buenos Aires, Argentina) obtained human serum samples from T. cruzi-infected patients who were in the asymptomatic chronic stage of the disease without cardiac or gastrointestinal compromise (age range: 11 to 51 years old, median age: 20). Serum samples were collected from clotted blood obtained by venipuncture and analyzed for T. cruzi-specific antibodies with commercially available kits: enzyme-linked immunosorbent assay (ELISA) using total parasite homogenate and indirect hemagglutination (IHA).

The team performed a serological assessment of 27 selected epitopes and of their use in a novel multipeptide-based diagnostic method. A combination of seven of these peptides was finally evaluated in ELISA format against a panel of 199 sera samples (Chagas-positive and negative, including sera from patients with leishmaniasis). The multipeptide formulation displayed a high diagnostic performance, with a sensitivity of 96.3% and a specificity of 99.2%.

The authors concluded that their results provided a novel, robust multi-epitope formulation as a basis for the development of improved peptide-based serodiagnosis for chagas disease. In contrast with chimeric DNA constructs that encode multiepitope recombinant proteins, the fact that this diagnostic reagent is based on the combination of short peptides that can be synthesized separately and easily formulated in a mix-and-match approach, means that it can be improved successively over time with only a reasonable effort. The study was published on October 9, 2017, in the journal Public Library of Science Neglected Tropical Diseases.

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National University of General San Martín