Dados do Trabalho

Título

Recombinant guanosine-5'-triphosphate (GTP)-binding protein associated with Poloxamer 407-based polymeric micelles protects against Leishmania infantum infection

Introdução

Visceral leishmaniasis (VL) represents a serious disease that affects and can kill million people in several countries in the world. Due to difficulties found in implementing effective prophylactic methods and in the treatment of the disease, the development of alternative measures, such as vaccines, is attractive. Leishmania virulence proteins should be considered as vaccine candidates against the disease, since they are involved in developing infection in mammalian hosts. In a previous study, a Leishmania guanosine-5'-triphosphate (GTP)-binding protein was identified as a parasite virulence fator, which could lead us to test it as a potential target for use in a vaccine against VL.

Objetivo (s)

The objective of the present study was to clone the encoding gene, express and purify the GTP protein in the recombinant form (rGTP), and use it as a candidate for a vaccine against L. infantum infection.

Material e Métodos

BALB/c mice were immunized with 25 µg of rGTP plus 25 μg of micelles (rGTP/Mic), 25 μg of empty micelles, 25 μg of rGTP plus 25 μg of saponin (rGTP/Sap), 25 μg of saponin alone or received only saline. Three doses were administered at two-week intervals and, 30 days after the last dose, animals were euthanized to collect their spleens and blood to perform immunological analyses. The remaining mice were infected with 10^7 L. infantum stationary promastigotes. Forty-five days after challenge, they were euthanized to obtain their organs and blood for evaluation of the parasitological and immunological response.

Resultados e Conclusão

Both rGTP/Sap and rGTP/Mic compositions induced a Th1-type immune response in vaccinated animals, with significantly higher levels of IFN-γ, IL-12, IL-2, TNF-α, GM-CSF, nitrite, specific IgG2a isotype antibody and positive lymphoproliferation, when compared to the control groups. This response was accompanied by significantly lower parasite load in the spleens, livers, bone marrows and draining lymph nodes of the animals. Immunological and parasitological evaluations indicated that rGTP/Mic induced a more polarized Th1-type response and higher reduction in the organs parasitism, with lower hepatotoxicity, when compared to the use of rGTP/Sap. In conclusion, our preliminary data suggest that rGTP could be considered for further development as a vaccine candidate to protect against VL.

Palavras-chave

GTP-binding protein; Th1 adjuvants; Vaccine; Visceral leishmaniasis.

Agradecimentos

CAPES, CNPq, FAPEMIG, Programa de Pós-graduação em Ciências da Saúde: Infectologia e Medicina Tropical