Seleção e avaliação da atividade protetora dos epítopos da proteína recombinante pb27 na paracoccidioidomicose experimental

Abstract

Paracoccidioides brasiliensis is a thermodymorphic fungus endemic in Latin America that causes a systemic mycosis called paracoccidioidomycosis (PCM). Conventional therapy for this mycosis involves a high financial cost, long treatment periods resulting in sequelae and frequent relapses. Therefore, the aim of this work is to select epitopes of the Pb27 protein, identified as antigen of the fungus, to use them in the formulation of therapeutic vaccine against PCM. 6 of the various epitopes predicted by B and T lymphocytes were selected by peptide immunoassay in spot against human sera. These peptides of Pb27 were synthesized and used as peptide vaccines (linked or unlinked) adsorbed on chitosan nanoparticles (NpCHO) in previously infected mice. Subsequently, two Euthanasia Points were performed for lung and serum analysis of the animals. The Colony Forming Unit assay demonstrated that therapeutic vaccine made up of NpCHO unlinked peptides (PEP SOL) reduced the fungal load to undetectable levels and NpCHO linked peptides (PEP LIG) reduced fungal load significantly. ELISA assay showed higher IgG levels in animals receiving the therapeutic NpCHO PEP LIG and NpCHO PEP SOL showed lower IgG levels, both compared to the control group. Primarily peptide 60 and 76 were the peptides most recognized by IgG of the animal group vaccinated with NpCHO PEP LIG compared to the control group. Primarily the subtype IgG 1 was detected at a higher level in animals serum vaccinated with NpCHO PEP LIG compared to the control. IgG2a and IgG2b were detected significantly in mice serum vaccinated with NpCHO PEP LIG. In histological analysis it was possible to observe reduction of fungal cells and inflammatory infiltrate in lungs of animals vaccinated with NpCHO PEP LIG and NpCHO PEP SOL preserving its morphology. It was possible to observe potential in peptide vaccine associated chitosan nanoparticles against PCM as an alternative therapy.