Human recombinant antibodies against Trypanosoma cruzi ribosomal P2β protein

Patients with chronic Chagas' Heart Disease (cChHD) develop an antibody response that is suspected to be involved in the cardiac pathogenesis. The response against Trypanosoma cruzi ribosomal P proteins is of particular interest, as these antibodies can cross-react with host cardiac receptors causing electrophysiological alterations. To better understand the humoral anti-P response we constructed a single-chain variable fragment library derived from a cChHD patient. The variable heavy and light regions were amplified from bone-marrow RNA and subcloned into the vector pComb3X. The phage library was subsequently panned against T. cruzi ribosomal P2β protein (TcP2β). We obtained 3 different human recombinant antibodies that specifically reacted with TcP2β in ELISA and Western blots. Two of them reacted with the C-terminal region of TcP2β, peptide R13, as the recombinant autoanti-P antibodies from Systemic Lupus Erythematosus (SLE) patients. Interestingly, the third one was specific for TcP2β but did not recognize R13, confirming the specific nature of the anti-P response in Chagas disease. Neither sequence nor VH usage similarities between Chagas and SLE anti-P autoantibodies were observed. Herein, the first human mAbs against TcP2β have been obtained and characterized showing that the humoral anti-P response is directed against the parasite and does not include an autoimmune component.