Imunoglobulina Y anti-metacestódeo de Taenia crassiceps: ferramenta promissora no imunodiagnóstico da neurocisticercose humana

Abstract

Neurocysticercosis (NCC) is a neglected tropical disease and its diagnosis remains a challenge due to nonspecific manifestations. Neuroimaging techniques are used in NCC diagnosis, however, due to the high cost of these methods and the advantages presented in the use of immunological tests, such as easiness to perform and satisfactory results, immunoassays are commonly used to detect antibodies against Taenia sp. antigens. The aim of this study was to produce, fractionate, isolate and characterize IgY antibodies from egg yolk of hens immunized with T. crassiceps metacestodes. Enzyme-linked immunosorbent assay (ELISA) indirect type, avidity ELISA, immunoblotting and indirect immunofluorescence tests were performed for characterization of IgY antibodies. ELISA index increased considerably from the week four, with growth of the production, and high avidity index (AI) were observed; IgY recognized immunodominant polypeptides bands with 24-215 kDa and immunofluorescence assays confirmed the potential of anti-T. crassiceps IgY antibodies to recognize T. crassiceps and T. solium metacestodes tissue. Diagnostic performance was verified by ELISA for immune complexes detection testing 90 serum samples divided into three groups: group 1 (n=30), individuals with NCC definitive diagnosis; group 2 (n = 30), individuals with other parasitic infections; and group 3 (n = 30) apparently healthy individuals. Values of sensitivity (Se), specificity (Sp), positive and negative likelihood ratios (LR+/LR-) and area under the curve (AUC) were calculated. Diagnostic parameters presented the following results: Se 83.3%; Sp 96.7%; LR+ = 25.0; LR− = 0.17 and AUC 0.966. For selection of peptides with binding affinity to anti-Tc and anti-dTc IgY antibodies by phage-display, a library of random peptides expressed in filamentous bacteriophages was used. Three main phage clones were identified, being C11 considered with the best diagnostic values for IgG detection in immunodiagnostic (C11 – Se 80%, Es 83.3%). Results of this study demonstrate that anti-T. crassiceps IgY antibodies present potential applicability and can be used as a promising tool in human NCC immunodiagnosis.