Dados do Trabalho

Título

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

Introdução

<p>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 <em>Leishmania infantum</em>.</p>

Objetivo (s)

<p>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.</p>

Material e Métodos

<p>Luciferase and DTL8 mRNA were <em>in vitro </em>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.&nbsp; 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.</p>

Resultados e Conclusão

<p>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 <em>L. amazonensis</em>, 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 <em>L. amazonensis</em>.</p>

Palavras Chave

Leishmaniasis; mRNA vaccine; recombinant protein; LNP formulation