Research paper The use of IgG antibodies in conventional and non-conventional immunodiagnostic tests for early prognosis after treatment of Chagas disease Ana Paula Barbosa Wendling a, b , Danielle Marquete Vitelli-Avelar a , Renato Sathler-Avelar a, b , Stefan Michael Geiger a , Andréa Teixeira-Carvalho a , Eliane Dias Gontijo c , Silvana Maria Elói-Santos b, c , Olindo Assis Martins-Filho a, ⁎ a Laboratório de Biomarcadores de Diagnóstico e Monitoração, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil b Departamento de Pós-Graduação em Patologia Geral, Faculdade de Medicina da Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil c Departamento de Propedêutica Complementar, Faculdade de Medicina da Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil article info abstract Article history: Received 21 March 2011 Received in revised form 9 May 2011 Accepted 11 May 2011 Available online 17 May 2011 Treatment success of chronically infected Chagas disease patients is laborious and a positive prognosis often is made only after repetitive serological and/or parasitological examinations with continuous negative results. Recently, we have developed a non-conventional flow- cytometric method in order to detect immunoglobulin G antibodies against live trypomastigote forms of Trypanosoma cruzi and showed its usefulness in the prognosis of treatment success. In the present study, we investigated the performance of flow-cytometric anti-live trypomasti- gote IgG antibodies (FC-ALTA) and flow-cytometric anti-fixed epimastigote IgG antibodies (FC-AFEA), as well as conventional serological methods, for early monitoring of benznidazole treated Chagas disease patients, e.g. 5 years after treatment. The analysis of individual FC-ALTA reactivity along the titration curve before and after treatment, we were able to show, that between 4% and 13% of treated patients under evaluation presented with reduced serological reactivity and segregated from the other patient groups. Similar results were obtained with semi-quantitative, conventional indirect hemagglutination or indirect immunofluorescence. Our data therefore suggest that the combined use of conventional and non-conventional serological methods could provide more suitable cure criteria in early post-therapeutic prognosis of Chagas disease. © 2011 Elsevier B.V. All rights reserved. Keywords: Chagas disease Trypanosoma cruzi Treatment Cure assessment Serology Flow cytometry 1. Introduction Human infection with Trypanosoma cruzi is endemic mainly in Latin America, affecting approximately eight million people in South and Central America and a further 100 million people are considered at risk (Weekly, 2007). However, with population movements from endemic to non- endemic countries there are estimates of more than 300,000 chagasic patients in the USA, N 5500 in Canada, N 80,000 in Europe and in the western Pacific region, turning Chagas disease into a public health problem outside the commonly considered countries and regions (Coura and Viñas, 2010). The treatment of Chagas disease in both acute and recent chronic infections may lead to cure or prevent pathological outcome in the later stages of disease (Ferreira, 1990; Urbina, 1999; Garcia et al., 2005). The indication of the etiological treatment in the chronic phase is still controversial because most treated patients continue to have positive conventional serology, even though their hemocultures become less frequently positive than those of the untreated, chronically Journal of Immunological Methods 370 (2011) 24–34 ⁎ Corresponding author at: Laboratório de Biomarcadores de Diagnóstico e Monitoração, Centro de Pesquisas René Rachou, Avenida Augusto de Lima 1715, Barro Preto, Belo Horizonte, Minas Gerais 30.190-002, Brazil. Tel.: + 55 31 3349 7764; fax: +55 31 3295 3115. E-mail address: oamfilho@cpqrr.fiocruz.br (O.A. Martins-Filho). 0022-1759/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.jim.2011.05.003 Contents lists available at ScienceDirect Journal of Immunological Methods journal homepage: www.elsevier.com/locate/jim