title: Applicability of a novel immunoassay based on surface plasmon resonance for the diagnosis of Chagas disease.
abstract: BACKGROUND
  We defined the methodological criteria for the interpretation of the results provided by a novel immunoassay based on surface plasmon resonance (SPR) to detect antibodies anti-Trypanosoma cruzi in human sera (SPRCruzi). Then, we evaluated its applicability as a diagnostic tool for Chagas disease.
  
  
  METHODS
  To define the cut-off point and serum dilution factor, 57 samples were analyzed at SPRCruzi and the obtained values of SPR angle displacement (ΔθSPR) were submitted to statistical analysis. Adopting the indicated criteria, its performance was evaluated into a wide panel of samples, being 99 Chagas disease patients, 30 non-infected subjects and 42 with other parasitic/infectious diseases. In parallel, these samples were also analyzed by ELISA.
  
  
  RESULTS
  Our data demonstrated that 1:320 dilution and cut-off point at ∆θSPR=17.2 m° provided the best results. Global performance analysis demonstrated satisfactory sensitivity (100%), specificity (97.2%), positive predictive value (98%), negative predictive value (100%) and global accuracy (99.6%). ELISA and SPRCruzi showed almost perfect agreement, mainly between chagasic and non-infected individuals. However, the new immunoassay was better in discriminate Chagas disease from other diseases.
  
  
  CONCLUSIONS
  This work demonstrated the applicability of SPRCruzi as a feasible, real time, label free, sensible and specific methodology for the diagnosis of Chagas disease.
authors.affiliation: Instituto de Ciências Exatas e Naturais, Universidade Federal de Mato Grosso (UFMT), Rondonópolis, MT, Brazil; Departamento de Farmácia, Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM), Diamantina, MG, Brazil.
authors.forename: João G G
authors.initials: JG
authors.lastname: Luz
authors.affiliation: Instituto Nacional de Ciência e Tecnologia em Bioanalítica, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil.
authors.forename: Dênio E P
authors.initials: DE
authors.lastname: Souto
authors.affiliation: Laboratório de Parasitologia, Universidade Federal de Juiz de Fora (UFJF), Campus Governador Valadares, MG, Brazil.
authors.forename: Girley F
authors.initials: GF
authors.lastname: Machado-Assis
authors.affiliation: Laboratório de Doenças de Chagas, Núcleo de Pesquisas em Ciências Biológicas (NUPEB), Universidade Federal de Ouro Preto (UFOP), Ouro Preto, MG, Brazil.
authors.forename: Marta
authors.initials: M
authors.lastname: de Lana
authors.affiliation: Departamento de Química, Universidade Federal do Maranhão (UFMA), São Luís, MA, Brazil.
authors.forename: Rita C S
authors.initials: RC
authors.lastname: Luz
authors.affiliation: Laboratório de Biomarcadores de Diagnóstico e Monitoração, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (CPqRR-FIOCRUZ/MG), Belo Horizonte, MG, Brazil.
authors.forename: Olindo A
authors.initials: OA
authors.lastname: Martins-Filho
authors.affiliation: Departamento de Química, Universidade Federal do Maranhão (UFMA), São Luís, MA, Brazil.
authors.forename: Flávio S
authors.initials: FS
authors.lastname: Damos
authors.affiliation: Departamento de Farmácia, Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM), Diamantina, MG, Brazil. Electronic address: helen.rmartins@gmail.com.
authors.forename: Helen R
authors.initials: HR
authors.lastname: Martins
mesh_terms: D000913:Antibodies, Protozoan / Q000097:blood* / Q000276:immunology; D014355:Chagas Disease / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D020349:Surface Plasmon Resonance / Q000379:methods*; D014344:Trypanocidal Agents / Q000097:blood* / Q000276:immunology
chemical_list: D000913:Antibodies, Protozoan; D014344:Trypanocidal Agents
keywords: Applicability; Chagas disease; Diagnosis; Immunoassay; Surface plasmon resonance