Potenciais vacinas e marcadores de diagnóstico para toxoplasmose baseados em peptídeos quiméricos

Abstract

Toxoplasmosis is a zoonotic worldwide disease caused by the protozoan Toxoplasma gondii (T. gondii), which can infect several warm-blooded animals, including humans. The most severe symptoms are usually observed in immunosupressed patients and could even be fatal. Due to the great biological diversity of non-clonal T. gondii isolates circulating in the southern hemisphere of the terrestrial globe, serious complications such as encephalitis, myocarditis and ocular damage can also be observed in immunocompetent individuals. Recently, a study revealed that T. gondii is also associated to the delineation of neurodegenerative diseases and a few types of cancers. Advances in immunoinformatics have been contributing with strategies to improve research on immunodominant epitopes contained in proteins from microorganisms, which can be recognized by host B and T cells. The study aims were to screen, analyze and select B and T cell epitopes contained in the Toxoplasma gondii AMA1, GRA7 and SAG1 proteins, as well as to construct chimeric peptides formed by the junction of B and T cell epitopes, and to analyze their immunogenic potential in silico and in vitro approaches. Four chimeric peptides were constructed, which showed binding affinities with murine and human MHC molecules in silico analyzes. A multi-antigenic epitopes chimera (TgAGS / BsT) was constructed from Toxoplasma gondii AMA1, GRA7 and SAG1 proteins by in silico analyzes, and expressed in recombinant system. The potential as diagnostic markers was confirmed by IgG recognition in serum-positive (n=10) for Toxoplasmosis by ELISA. Through antigenic stimuli in PBMC culture from immunocompetent serum-negative and serum-positive Toxoplasmosis persons, the expression of CD25 + in CD3 + cells was induced in the positive group of persons, with significance results (p<0.05), when compared to negative individuals. In addition, the production of IFN-y and IL-2 cytokines were found in supernatant cultures stimulated by the chimeric peptides. These findings open perspectives for the development of vaccines and diagnostic reagents for Toxoplasmosis through chimeric products formed by B-cell epitopes and T.