Vacinologia reversa: avaliação preliminar da resposta imunológica contra leishmaniose visceral no modelo experimental mesocricetus auratus imunizados com um peptídeo sintético da GP63 de leishmania major

Abstract

Leishmaniasis is a neglected disease caused by unicellular protozoa of the genus Leishmania. According to the World Health Organization, the disease is classified into two clinical forms: tegumentary leishmaniasis (LT) and visceral leishmaniasis (LV). LV, also known as calazar, is the most severe form, potentially fatal in untreated individuals. Actually, one of the major challenges encountered in studies of the increasing urbanization of visceral leishmaniasis (LV) is the development of highly effective vaccines to induce protection against Leishmania infection. In this context, the present study was elaborated in order to carry out a preliminary analysis of the safety and immunogenicity of a possible candidate vaccine against LV, constituted of a synthetic peptide of the glycoprotein gp63 of Leishmania major with prediction for MHC of class I, using the hamster (Mesocricetus auratus) as an experimental model. A total of nine animals were distributed in three experimental groups, among them: (i) control group (C, n = 3), that received 100 μL 0.85% sterile saline solution; (Ii) Montanide ISA-61VG (ISA, n = 3) adjuvant group that received 30 μL of Montanide, diluted in 70 μL of 0.85% sterile saline and (iii) group immunized with MCH-I peptide Leishmania Major and Montanide ISA-61VG adjuvant (Lm-ISA, n = 3) that received 30 μL of the antigen/dose, diluted in 40 μL of 0.85% sterile saline and emulsified with 30 μL of the Montanide ISA-61VG oily adjuvant. The inocula were administered subcutaneously in three doses at 14 day intervals. Samples of blood, serum and spleen fragments were collected for different laboratory tests at different times. Biochemical profile of renal and hepatic function, leukocyte framework, antibody titration and lymphoproliferation of splenocytes were the targets of this study. Our results revealed that the formulation was innocuous and non-toxic to the animals, since serum levels of urea, creatinine and hepatic enzymes: alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (AF) were maintained within the patterns of normality described in the literature. In addition, the formulation was capable to induce a humoral anti-Leishmania specific response by total IgG dosages. In response to the white series and lymphoproliferation of spleen cells, the existence of immunological memory was verified through a significant increase in the leukocyte population, as well as the high lymphoproliferative activity obtained in the vaccine group.