Potential immunoprophylactic use of a multi-epitope protein of CD4+ and CD8+ T cells against visceral leishmaniasis in Balb/c mice

Diseases caused by parasites of the genus Leishmania are considered neglected infections. Visceral leishmaniasis (VL) is the most severe form of the disease, with a high annual incidence worldwide. In Brazil, dogs play an essential role as reservoirs, exhibiting a high concentration of parasites on their skin and no clinical signs, making them potential transmitters of the disease. Given the need for an efficient method to reduce the incidence of the disease, this study aimed to develop a gene encoding a chimeric protein with multiple epitopes that target both CD4⁺ and CD8⁺ T lymphocytes. Together with the MPLA adjuvant, the chimeric protein has the potential to compose a vaccine formulation against canine visceral leishmaniasis. Using an immunoinformatics analysis tool, the prediction of specific epitopes for CD4⁺ and CD8⁺ T lymphocytes was performed on sequences of hypothetical proteins previously identified in the immunoproteome of Leishmania (Leishmania) infantum parasites. The vaccine formulation was evaluated in Balb/c mice, and the chimeric protein, in association with the adjuvant, induced a protective response with a polarized T_H1 profile against the Leishmania parasite, characterized by high levels of IFN-γ, TNF-α, and low levels of IL-10. Additionally, the vaccinated animals showed a significant reduction in parasite burden in the liver, spleen, and bone marrow and draining lymph nodes of the paws compared to the control groups. Thus, the chimeric protein described here has the potential to be used in a vaccine formulation against canine leishmaniasis.