Avaliação da imunogenicidade e eficácia protetora induzida por bacteriófagos recombinantes selecionados pela tecnologia de Phage Display em camundongos BALBc contra a infecção por Leishmania infantum

Abstract

Visceral leishmaniasis (VL) is a parasitic disease that has a high incidence in Brazil and, if untreated, can lead to death. The prevention and control of the disease are important, but they present problems due to the difficulty in interrupting the vector cycle, the toxicity of the drugs used and the absence of human vaccines. Therefore, the development of vaccines for the prophylaxis of VL is a meaningly needed and the use of new technologies, such as Phage Display, can provide the search of new vaccine targets. In the present study, the Phage Display technique was used to select bacteriophages with peptides exposed on their surface that were specific for IgG antibodies from patients with symptomatic asymptomatic VL and that were not recognized by antibodies from uninfected individuals. Selected phage clones were used as peripheral blood mononuclear cell stimuli obtained from healthy and VL patients, and those with high IFN-γ / IL-10 ratio were selected for the vaccination assays. Among the 25 clones obtained in the biopannings cycles, two were selected because the ratio IFN-γ and IL-10 was greater than 3.0, being called clones B1 and D11, for the vaccination experiments in BALB / c mice, with the aim of validating its protective efficacy against Leishmania infantum infection. It was found that both clones induced significant protection against the infection, evidenced by the reduction of parasitism in all evaluated organs: spleen, draining lymph node, bone marrow and liver, process mediated by a specific Th1-type immune response. The present study is innovative as it employs a rational strategy based on in vitro and in vivo tests with recombinant bacteriophages in order to select new and promising immunogens against VL.