Chimeric Vaccines Designed by Immunoinformatics-Activated Polyfunctional and Memory T Cells That Trigger Protection against Experimental Visceral Leishmaniasis

Abstract

Many vaccine candidates against visceral leishmaniasis (VL) have been proposed; however, to date, none of them have been efficacious for the human or canine disease. On this basis, the design of leishmaniasis vaccines has been constantly changing, and the use of approaches to select specific epitopes seems to be crucial in this scenario. The ability to predict T cell-specific epitopes makes immunoinformatics an even more necessary approach, as in VL an efficient immune response against the parasite is triggered by T lymphocytes in response to Leishmania spp. immunogenic antigens. Moreover, the success of vaccines depends on the capacity to generate long-lasting memory and polyfunctional cells that are able to eliminate the parasite. In this sense, our study used a combination of different approaches to develop potential chimera candidate vaccines against VL. The first point was to identify the most immunogenic epitopes of Leishmania infantum proteins and construct chimeras composed of Major histocompatibility complex (MHC) class I and II epitopes. For this, we used immunoinformatics features. Following this, we validated these chimeras in a murine model in a thorough memory study and multifunctionality of T cells that contribute to a better elucidation of the immunological protective mechanisms of polyepitope vaccines (chimera A and B) using multicolor flow cytometry. Our results showed that in silico-designed chimeras can elicit polyfunctional T cells producing T helper (Th)1 cytokines, a strong immune response against Leishmania antigen, and the generation of central and effector memory T cells in the spleen cells of vaccinated animals that was able to reduce the parasite burden in this organ. These findings contribute two potential candidate vaccines against VL that can be used in further studies, and help in this complex field of vaccine development against this challenging parasite.

Leishmania LiHyC protein is immunogenic and induces protection against visceral leishmaniasis

“…A flow cytometry assay was performed to evaluate the frequency of T‐cell subtypes producing IFN‐γ, TNF‐α, IL‐2 and IL‐10, as described previously 32 . For this, spleen cells (5 × 10 6 per well) were incubated in 200 μl of complete RPMI medium in 96‐well round‐bottom culture plates.…”

“…A flow cytometry assay was performed to evaluate the frequency of T-cell subtypes producing IFN-γ, TNF-α, IL-2 and IL-10, as described previously. 32 For this, spleen cells (5 Cells were acquired (100,000 events) on LSRFortessa cytometer (BD Pharmingen) using FACSDiva software. For analysis in FlowJo software, non-alive cells were excluded after FVS450 stain and live cells were gated for stained CD4 + or CD8 + T-cell subtypes and intracellular cytokine presence.…”

Acarbose presents in vitro and in vivo antileishmanial activity against Leishmania infantum and is a promising therapeutic candidate against visceral leishmaniasis

“…Cells were incubated with phorbol myristate acetate (5.0 ng/mL), ionomycin (1.0 μg/mL) or lipopolysaccharide (0.01 μg/uL), diluted in complete RPMI medium. Afterwards, cells were treated with Brefeldin A (10.0 μg/mL) for 4 h, and stained with Fixable Viability Stain 450 (BD Biosciences) for 15 min at room temperature, followed by anti-mouse CD3 FITC (clone 145.2C11), anti-mouse CD4 BV605 (clone RM4-5) or anti-mouse CD8α PerCP Cy5.5 (clone 53–6.7) (BD Biosciences Bioscience, USA), for 30 min at room temperature [ 6 ]. Next, fixation (FACS fixing solution), washing and permeabilization were performed.…”

Host–Pathogen Interaction in Leishmaniasis: Immune Response and Vaccination Strategies

“…1 × 10 7 promastigotes of L. infantum challenge. Brito et al designed Chimera A by mapping T cell epitopes of known L. infantum antigens [282]. This chimera A formulated with MPL-A stimulated Th1 response with IFN-γ, INF-α, IL-2 expression and decreased IL-4 and IL-10 expression along with reduced splenic parasitic load [283].…”