The proteome of Trypanosoma cruzi shed vesicles involved in host immunomodulation and cell invasion

Abstract

Infective trypomastigote forms of Trypanosoma cruzi release vesicles to the culture medium that are rich in α-galactosyl residues (TcαGalVes). These vesicles induce potent proinflammatory host immune response and greatly enhance host cell invasion by the parasite. For proteomic analysis, the conditioned medium from cell-derived trypomastigotes was fractionated by gel-filtration, followed by affinity chromatography using anti-αGal antibodies. TcαGalVes were digested with proteases using three different strategies. To increase protein coverage, released peptides were fractionated by strong cation-exchange chromatography followed by reverse-phase chromatography, and analyzed by ESI-MS/MS. MS/MS spectra were correlated to TcruziDB v3.0 using Sequest, Phenyx and Mascot algorithms. We identified 126 proteins, including several members of the trans-sialidase (TS)/gp85 and gp63 superfamilies, known to play a key role in host cell adhesion and invasion by the parasite. We also found several polypeptides related to mammalian cell exosomes. Our data clearly show that TcαGalVes contain the major virulence factors of T. cruzi, responsible for promoting the parasite entry into the host cell, and for its evasion from the host immune response. Supported by BBRC/Biology (NIH#5G12RR008124), FAPESP, and the Wellcome Trust.