Immunogenicity of Multi-Epitope Recombinant Protein as an Antigen Candidate for Chagas Disease Vaccine in Humans.

Chagas disease, caused by the protozoan (), is the most significant neglected tropical disease affecting individuals in the Americas. Currently, available drugs, such as nifurtimox and benznidazole (BZN), are both toxic and ineffective in the chronic phase of the disease. A promising alternative is the development of a Chagas disease vaccine, although this effort is hampered by the complexity of the parasite and HLA polymorphisms. In addition, the activation of epitope-specific CD8 T cells is critical to conferring a robust cell-mediated immune response and protection by producing IFN-γ and perforin. Thus, the antigen (s) for the development of a Chagas vaccine or immunotherapy must include CD8 T cell epitopes. In this study, we aimed to develop a multi-epitope recombinant protein as a novel human vaccine for Chagas disease. Sixteen database programs were used to predict 40 potential epitopes for the HLA-A02:01 allele. Nine out of the 40 predicted epitopes were able to elicit IFN-γ production in Peripheral Blood Mononuclear Cells (PBMCs) from Chagas patients. Molecular docking revealed a good binding affinity among the epitopes with diverse HLA molecules. Therefore, a recombinant multi-epitope protein including these nine CD8 epitopes was expressed and demonstrated to recall an antigen-specific immune response in assays using PBMCs from Chagas patients with the HLA-A02 allele. These findings support the development of this multi-epitope protein as a promising candidate human vaccine against Chagas disease.