Development of an immunogen containing CD4+/CD8+ T-cell epitopes for the prophylaxis of tegumentary leishmaniasis

Tegumentary leishmaniasis (TL) is a disease of high severity and incidence in Brazil, and Leishmania braziliensis is its main etiological agent. The inefficiency of control measures, such as high toxicity and costs of current treatments and the lack of effective immunoprophylactic strategies, makes the development of vaccines indispensable and imminent. In this light, the present work developed a gene encoding multiple T-cell (CD4(+)/CD8(+)) epitope, derived from conserved proteins found in Leishmania species and associated with TL, to generate a chimeric protein (rMEP/TL) and compose a vaccine formulation. For this, six T-cell epitopes were selected by immunoinformatics approaches from proteins present in the amastigote stage and associated with host-parasite interactions. The following formulations were then tested in an L. braziliensis murine infection model: rMEP/TL in saline or associated with MPLA-PHAD (R). Our data revealed that, after immunization (three doses; 14-day intervals) and subsequent challenging, rMEP/TL and rMEP/TL + MPLA-vaccinated mice showed an increased production of key immunological biomarkers of protection, such as IgG(2a), IgG(2a)/IgG(1), NO, CD4(+), and CD8(+) T-cells with IFN-gamma and TNF-alpha production, associated with a reduction in CD4(+)IL-10(+) and CD8(+)IL-10(+) T-cells. Vaccines also induced the development of central (CD44(high)CD62L(high)) and effector (CD44(high)CD62L(low)) memory of CD4(+) and CD8(+) T-cells. These findings, associated with the observation of lower rates of parasite burdens in the vaccinated groups, when compared to the control groups, suggest that immunization with rMEP/TL and, preferably, associated with an adjuvant, may be considered an effective tool to prevent TL. Key points Rational design approaches for vaccine development. Central and effector memory of CD4+ and CD8+ T-cells. Vaccine comprised of rMEP/TL plus MPLA as an effective tool to prevent TL.

Automated summary

A gene encoding a chimeric protein with multiple T-cell epitopes was developed as a potential vaccine for tegumentary leishmaniasis. Vaccinated mice showed an increased production of key immunological biomarkers associated with protection against TL and a reduction in cells associated with TL. The vaccine also induced the development of memory T-cells and led to lower parasite burdens.