Dados do Trabalho

Título

Development of mRNA vaccines for leishmaniasis and comparison with vaccines based on recombinant antigens

Introdução

Despite studies in animal models with defined subunit vaccines, to date, no vaccine is available for human leishmaniasis. As demonstrated during the COVID-19 pandemic, messenger RNA (mRNA) vaccines have proven to be a technological innovation. Therefore, we decided to develop an mRNA vaccine using the kinetoplast-associated protein (PAK) as the target antigen. Previous studies have shown that immunization of mice with recombinant PAK, named rDTL8, was able to generate a Th1 response that partially reduced the parasite load in animals after challenge with Leishmania infantum.

Objetivo (s)

In this work we aimed to develop an mRNA vaccine and compare its immunogenicity and protection levels with immunization with a recombinant protein vaccine based on the same antigen. Additionally, we aimed to compare heterologous prime-boost-boost immunization using mRNA and recombinant protein with homologous prime-boost-boost immunization using only protein and to this aim we used a LNP formulation, to encapsulated mRNAs, designed by our group.

Material e Métodos

Luciferase and DTL8 mRNA were in vitro transcribed and encapsulated in lipid nanoparticles (LNPs). LNPs with luciferase mRNA were characterized by cryogenic transmission electron microscopy and were also injected into BALB/c mice for biodistribution analysis (CEUA/Fiocruz: LW-34/22 (P-22/22.5)). Following, C57BL/6 mice were immunized with LNPs with DTL8 mRNA, or DTL8 protein using a prime-boost-boost protocol.  Immunogenicity was evaluated through antibody and IFN-γ production. Thirty days after the last immunization the animals were challenged with Leishmania amazonensis and protection was evaluated by limiting dilution.

Resultados e Conclusão

The homologous prime-boost-boost protocol showed that animals immunized with DTL8 mRNA produced high levels of antibody compared to mice immunized with rDTL8, however, immunization with rDTL8 generates high levels of IFN-γ. After challenge with L. amazonensis, we observed that animals immunized with rDTL8 or LNP mRNA DTL8 were partially protected against infection at similar levels. The heterologous prime-boost-boost immunization protocol showed similar levels of total IgG induction, however immunization with at least one dose of rDTL8 protein is necessary for production of detectable levels of IFN-γ. We are currently evaluating protection in mice immunized with the heterologous prime-boost-boost protocol. So far, our results demonstrate a promising potential of mRNA vaccines for inducing protection against L. amazonensis.

Palavras Chave

Leishmaniasis; mRNA vaccine; recombinant protein; LNP formulation