E6020 is a synthetic agonist of Toll‐like receptor‐4 (TLR4). The purpose of this study was to evaluate the effect of different doses of E6020‐SE on Trypanosoma cruzi‐specific immune responses and its ...ability to confer protection against acute lethal infection in mice. Forty female BALB/c were infected with 500 trypomastigotes of T cruzi H1 strain, divided into four groups (n = 10) and treated at 7‐ and 14‐day post‐infection (dpi) with different doses of E6020‐SE or PBS (control). Survival was followed for 51 days, mice were euthanized and hearts were collected to evaluate parasite burden, inflammation and fibrosis. We found significantly higher survival and lower parasite burdens in mice injected with E6020‐SE at all doses compared to the control group. However, E6020‐SE treatment did not significantly reduce cardiac inflammation or fibrosis. On the other hand, E6020‐SE modulated Th1 and Th2 cytokines, decreasing IFN‐γ and IL‐4 in a dose‐dependent manner after stimulation with parasite antigens. We conclude that E6020‐SE alone increased survival by decreasing cardiac parasite burdens in BALB/c mice acutely infected with T cruzi but failed to prevent cardiac damage. Our results suggest that for optimal protection, a vaccine antigen is necessary to balance and orient a protective immune response.
•The recombinant multi-epitope Tc24-C4.10E reduces parasitemia peak in acute T. cruzi infected mice.•The recombinant multi-epitope Tc24-C4.10E elicit an antigen-specific CD8 + T cell response ...producing IFNγ and IL-4 cytokines.•This is the first approach using as scaffold a recombinant protein to fuse 10 CD8 + T. cruzi epitopes.
About 6.5 million people worldwide are afflicted by Chagas disease, which is caused by the protozoan parasite Trypanosoma cruzi. The development of a therapeutic vaccine to prevent the progression of Chagasic cardiomyopathy has been proposed as an alternative for antiparasitic chemotherapy. Bioinformatics tools can predict MHC class I CD8 + epitopes for inclusion in a single recombinant protein with the goal to develop a multivalent vaccine. We expressed a novel recombinant protein Tc24-C4.10E harboring ten nonameric CD8 + epitopes and using Tc24-C4 protein as scaffold to evaluate the therapeutic effect in acute T. cruzi infection. T. cruzi-infected mice were immunized with Tc24-C4.10E or Tc24-C4 in a 50-day model of acute infection. Tc24-C4.10E-treated mice showed a decreased parasitemia compared to the Tc24-C4 (non-adjuvant) immunized mice or control group. Moreover, Tc24-C4.10E induced a higher stimulation index of CD8 + T cells producing IFNγ and IL-4 cytokines. These results suggest that the addition of the MHC Class I epitopes to Tc24-C4 can synergize the antigen-specific cellular immune responses, providing proof-of-concept that this approach could lead to the development of a promising vaccine candidate for Chagas disease.
Leishmaniasis is a vector-borne neglected tropical disease caused by the Leishmania spp. The disease is transmitted to humans and animals by the bite of infected female sandflies during the ingestion ...of bloodmeal. Because current drug treatments induce toxicity and parasite resistance, there is an urgent need to evaluate new drugs. Most therapeutics target the differentiation of promastigotes to amastigotes, which is necessary to maintain Leishmania infection. However, in vitro assays are laborious, time-consuming, and depend on the experience of the technician. In this study, we aimed to establish a short-term method to assess the differentiation status of Leishmania mexicana (L. mexicana) using flow cytometry. Here, we showed that flow cytometry provides a rapid means to quantify parasite differentiation in cell culture as reliably as light microscopy. Interestingly, we found using flow cytometry that miltefosine reduced promastigote-to-amastigote differentiation of L. mexicana. We conclude that flow cytometry provides a means to rapidly assay the efficacy of small molecules or natural compounds as potential anti-leishmanials.
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•Flow cytometry provides a rapid means to quantify L. mexicana parasite differentiation in 24nullh post-incubation.•FSC and SSC parameters are enough robust to measure the differentiation stage of L. mexicana in a 24 h-drug assay.•Flow cytometry is reliable and rapid method compared to microscopy in drug assays with axenic L. mexicana parasites.
