Immunological characterization of synthetic peptides representing natural sequences of Leishmania spp.

Abstract

The development of vaccines against diseases caused by intracellular parasites requires elucidating the associated molecular mechanisms, particularly identifying peptides (T cell epitopes) that can stimulate T cell receptors. Worldwide, numerous studies are being conducted to identify and characterize antigenic components of Leishmania that can be used in disease detection and/or in therapeutic trials to prevent infection or post-infection. In this regard, our laboratory has been dedicated for several years to the search for and identification of natural peptides from Leishmania spp. with the potential to stimulate T cell subpopulations that produce cytokines associated with protection against the disease. In previous immunological studies, using sera and peripheral blood mononuclear cells (PBMCs) from patients with leishmaniasis and fractions of natural peptides from Leishmania brasiliensis (obtained in our laboratory), we have detected significant reactivity in two of the fractions tested. The objective of this work is the immunological characterization of four synthetic peptides (representing the sequences of the natural peptides present in the indicated peptide fractions) against cells and sera from patients with and without treatment. The results showed the ability of the peptides to generate stimulation of primary cellular prostaglandins (PCPs) with a Th1 cellular response. Three of the peptides tested showed the greatest reactivity in the immunoassays (MABA and peptide-ELISA), suggesting further serological specificity assays with a larger number of patient sera and studies with experimental animals using the individual peptides and mixtures thereof to evaluate the possibility of their inclusion in diagnostic assays and/or immunotherapies.