Vesículas extracelulares de Trypanosoma cruzi e Trypanosoma rangeli: estudo comparativo de componentes antigênicos proteicos

Abstract

Trypanosoma cruzi infection causes Chagas disease and affects about 8 million people worlwide. T. cruzi can release extracellular vesicles (EVs) that act in the host cell-parasite interaction and contribute to the success of infection, by carrying functional molecules such as proteins and small RNAs. Trypanosoma rangeli, an avirulent protozoan, can trigger a partial immune protection against T. cruzi in animals, a response associated with membrane antigens shared between both parasites. The mechanisms and componds involved in this protective response have not been fully elucidated. Previous data from our group showed that EVs from T. cruzi and T. rangeli are immunogenic and present cross-reaction in the sera of animals previously infected, as well as in the sera of chagasic patients. Therefore, this study aimed to identify the antigenic proteins of EVs from T. cruzi and T. rangeli. The EVs from epimastigote forms were purified, characterized by NTA and treated for protein extraction. The antigenic evaluation was performed through Western blot (WB) and ELISA, with total extract of epimastigotes and EVs from Vero cells as controls. Lastly, the identification of T. rangeli and T. cruzi EVs proteomes was performed by mass spectrometry (LC-MS/MS) and bioinformatic analyzes. The electrophoretic profiles of EVs from T. cruzi and T. rangeli revealed common bands (~50 kDa). However, the process of lysis and/or the denaturing conditions did not allow the visualization of the immunoreaction profiles of these EVs against murine sera by WB. On ELISA, there was also an absence of immune reaction for the murine sera tested in lysed EVs. Only when native EVs were tested cross-reactivity was shown. The unpublished analysis of the proteome of EVs from T. rangeli epimastigotes revealed 101 proteins, 14 were common to the proteins identified in T. cruzi epimastigotes and/or trypomastigotes EVs, 5 had a host-parasite interaction role (homologous to T. cruzi proteins), besides the presence of several typical molecules of EVs. Among the 14 proteins shared between T. cruzi and T. rangeli EVs, two had immunogenic epitopes identified in silico (KMP-11 and pyrophosphatase of proton vacuolar 1). Our results reinforce the antigenic similarity between those EVs and suggest that the immunogenicity of these EVs comes from membrane surface proteins. The data corroborate with the potential vaccine of T. rangeli EVs for Chagas disease and/or its application as a biomarker, and also distingish targets to be evaluated in further studies in these areas.