Leishmania pyruvate kinase and mitochondrial processing protease: Two novel vaccine candidates, selected via a seroproteomic approach, trigger a protective immune response against murine cutaneous leishmaniasis

Abstract

American tegumentary leishmaniasis (ATL) is a neglected tropical disease that affects millions of people worldwide, for which no effective vaccine or optimal treatment is currently available. In this study, we evaluated the effectiveness of Leishmania recombinant antigens selected through a seroproteomic approach using a murine model. Two Leishmania (Viannia) braziliensis antigens, identified as human anti-Leishmania IgG2-reactive but IgG3 non-reactive, markers subtypes for Th1 and Th2 responses respectively, were selected for immunization of BALB/c mice formulated with Quil-A® (QA) adjuvant. Vaccine efficacy was assessed based on lesion size, parasite burden, levels of IFN-γ and IL-10, delayed-type hypersensitivity (DTH) response, and antibody production against both recombinant and crude Leishmania antigens. Pyruvate kinase (PK) and mitochondrial processing protease (MPP) were identified. Both antigens combined with QA significantly reduce the parasite load and lesion size. The group immunized with the combination MPP+PK+QA, which used lower concentrations of each antigen, showed a greater reduction in parasite burden compared to the single-antigen groups (MPP+QA and PK+QA). Quil-A® enhanced the immunogenicity of rPK, as indicated by increased IFN-γ levels. Additionally, rPK induced IL-10 production at levels comparable to the control group. Both PK+QA and MPP+PK+QA elicited a significant DTH response after Leishmania challenge. Most vaccinated groups exhibited an early immune response to whole Leishmania antigens, with a Th1-biased profile observed in the PK+QA and MPP+PK+QA groups. These findings offer valuable insights into antigen selection based on antibody subclass profiling and identify two novel vaccine candidates with potential for the development of effective vaccines against ATL.