Antigenic and functional studies on Trypomastigote Small Surface Antigen protein of Trypanosoma cruzi

BALOUZ VIRGINIA; MARÍA DE LOS MILAGROS CÁMARA; GASPAR CANEPA; SANTIAGO CARMONA; ROMINA VOLCOVICH; JAIME ALTCHEH; FERNAN AGUERO; CARLOS A. BUSCAGLIA

Mar del Plata

Congreso; Sociedad Argentina de Protozoología; 2014

Sociedad Argentina de Protozoología

Trypanosoma cruzi is the etiological agent of Chagas disease. TSSA (Trypomastigote Small Surface Antigen) is a 92-aa long mucin-like glycoprotein displayed on the surface of infective trypomastigote forms that elicits strong antibody responses in T. cruzi-infected humans. In addition, TSSA functions as a parasite adhesin, engaging surface receptor(s) and inducing signaling pathways on the host cell as a prerequisite for trypomastigote internalization. Here, we used synthetic peptides and recombinant deletion molecules to map the antigenic region of TSSA-CL, the TSSA isoform expressed by the CL Brener clone. We verified specific antibody reactivity for most of the central region of TSSA-CL (from residue 24 to 58), indicating a complex linear B-cell epitope repertoire. Additional studies allowed us to define a 21-aa peptide (termed E2E3) showing the same performance (in terms of sensitivity and specificity) as serodiagnostic reagent for Chagas Disease than the whole TSSA-CL molecule. Tools generated to carry out these antigenic characterizations were further used to explore the variability of anti-TSSA-CL humoral responses along the human infection and to map the adhesive motifs of TSSA-CL towards non-macrophagic cell lines. Regarding the latter issue, we show that 2 discrete 15-aa peptides from TSSA-CL bound to HeLa cell monolayers in a dose-dependent manner. This binding has a functional correlate, since when exogenously added these peptides were able to significantly inhibit both adhesion and internalization of CL Brener trypomastigotes. These peptides, however, did not impair adhesion/internalization of CL Brener amastigotes (which do not express TSSA) or of Sylvio X-10 trypomastigotes (which display a different TSSA isoform on their surface), further supporting the specificity of our results. Overall, our data provide novel insights into the function and diagnostic properties of TSSA.