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.