Screening of a cDNA library from Trypanosoma cruzi with sera from chronic Chagas heart disease patients allows the identification of a parasite polypeptide specifically recognized by sera from patients with cardiomyopathy. This polypeptide is part of a ribosomal P2 protein (Tc-P2) of acidic ribosomal protein' family. A unique epitope is recognized that is located at the C terminus of the molecule whose sequence is very conserved. Particularly, the sequence of its human counterpart differs only in aminoacid at position 11, where a serine is replacing a glutamic acid. A monoclonal antibody specific of Tc-P2 C terminus (mAb 17.2) recognizes an epitope on the second extra-cellular loop of the b1-adrenergic receptor on cardiocytes in vitro. It exerts a chronotropic effect and its activity is currently studied in vivo.
Attempts for crystallization of the mAb 17.2-Fab with Tc-P2 have been started. The definition of the interactions of the antibody with specific aminoacids of the b1-adrenergic receptor might contribute to the design of new beta-blocking drugs useful for patients with Chagas disease but also for patients with idiopathic dilated cardiomyopathy that has some common features and whose etiology is still unknown.