Applicability of a novel immunoassay based on surface plasmon resonance for the diagnosis of Chagas disease

• SPRCruzi is a novel immunoassay based on SPR for the diagnosis of Chagas disease.
• Methodological criteria were defined for the interpretation of the results of SPRCruzi.
• SPRCruzi has high performance in discriminating chagasic and non-infected patients.
• SPRCruzi is better than ELISA in discriminate Chagas disease from other diseases.

BackgroundWe 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.MethodsTo 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.ResultsOur 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.ConclusionThis work demonstrated the applicability of SPRCruzi as a feasible, real time, label free, sensible and specific methodology for the diagnosis of Chagas disease.