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Journal of Clinical Microbiology, October 2006, p. 3768-3774, Vol. 44, No. 10
0095-1137/06/$08.00+0     doi:10.1128/JCM.01043-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Design, Construction, and Evaluation of a Specific Chimeric Antigen To Diagnose Chagasic Infection

Instituto de Tecnología Biológica, INTEBIO, Universidad Nacional del Litoral, Santa Fe, Argentina,¹ Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brasil,² Centro de Pesquisas Aggeu Magalhães, Fundação Oswaldo Cruz, Recife, Brasil,³ Departamento de Química Analítica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina⁴

Received 18 May 2006/ Returned for modification 4 July 2006/ Accepted 31 July 2006

Chagas' disease is routinely diagnosed by detecting specific antibodies (Abs) using serological methods. The methodology has the drawback of potential cross-reactions with Abs raised during other infectious and autoimmune diseases (AID). Fusion of DNA sequences encoding antigenic proteins is a versatile tool to engineer proteins to be used as sensitizing elements in serological tests. A synthetic gene encoding a chimeric protein containing the C-terminal region of C29 and the N-terminal region of TcP2ß was constructed. A 236-serum panel, composed of 104 reactive and 132 nonreactive sera to Chagas' disease, was used to evaluate the performance of the chimera. Among the nonreactive sera, 65 were from patients with AID (systemic lupus erythematosus and rheumatoid arthritis) or patients infected with Leishmania brasiliensis, Brucella abortus, Streptococcus pyogenes, or Toxoplasma gondii. The diagnostic performances of the complete TcP2ß (TcP2ß_FL) and its N-terminal region (TcP2ß_N) were evaluated. TcP2ß_FL showed unspecific recognition toward leishmaniasis (40%) and AID Abs (58%), while TcP2ß_N showed no unspecific recognition. The diagnostic utility of the chimera was evaluated by analyzing reactivity and comparing the results with those obtained with TcP2ß_N. The chimera reactivity was higher than that of the peptide fractions (0.874 versus 0.564 optical density, P = 0.0017). The detectability and specificity were both 100% for the whole serum panel tested. We conclude that the obtained chimera shows an improved selectivity and sensitivity compared with other ones previously reported, therefore displaying an optimized performance for Trypanosoma cruzi infection diagnosis.