Usefulness of gel filtration fraction as potential biomarker for neurocysticercosis in serum: towards a new diagnostic tool.

There is an increasing interest in improving neurocysticercosis (NCC) diagnosis through the search of new and alternative antigenic sources, as those obtained from heterologous antigens. The aim of this study was to obtain potential biomarkers for NCC diagnosis after gel filtration chromatography [gel filtration fraction (GFF)] from the total saline extract (SE) from Taenia saginata metacestodes, followed by protein identification and application in immunodiagnostic. SE and GFF proteic profiles were characterized in gel electrophoresis, and diagnostic performance was verified by testing 160 serum samples through enzyme-linked immunosorbent assay and immunoblotting. Sensitivity (Se), specificity (Sp) and other diagnostic parameters were calculated. Polypeptides of interest in the diagnosis of human NCC present at GFF were analysed by mass spectrometry (MS) and B-cell epitopes were predicted. GFF had the best diagnostic parameters: Se 93·3%; Sp 93%; AUC 0·990; LR+ = 13·42 and LR- = 0·07, and proved to be useful reacting with serum samples in immunoblotting. Proteic profile ranged from 64 to 68 kDa and enolase and calcium binding protein calreticulin precursor were identified after MS. The enolase and calcium-binding protein calreticulin precursor showed 18 and 10 predicted B-cell epitopes, respectively. In conclusion we identified important markers in the GFF with high efficiency to diagnose NCC.

Ion-exchange protocol to obtain antigenic fractions with potential for serodiagnosis of strongyloidiasis.

The aim of this study was to fractionate and partially characterize the antigenic extract of filariform larvae of Strongyloides venezuelensis in ion-exchange resin diethylaminoethyl sepharose (DEAE), to obtain antigenic fractions potentially applicable in immunoassays. Somatic antigen (SA) and its fractions DEAE S1 and DEAE S2 - which interacted with the resin - were evaluated by 1-dimensional electrophoresis to obtain protein profiles. SA and its fractions were tested in serum samples for IgG detection by ELISA. Serum samples (n = 155) were analysed: 50 from strongyloidiasis patients (G1), 55 from patients with other parasitic infections (G2) and 50 from healthy volunteers. Sensitivity (Se), specificity (Sp), area under curve (AUC) and likelihood ratios (LR) were calculated. The DEAE S2 fraction provided a high diagnostic value for IgG detection (Se 92·0%, Sp 91·4%, AUC 0·981, LR+ 10·75, LR - 0·09). In conclusion, the DEAE S2 fraction would probably be a source of immunodominant polypeptides for IgG detection in human strongyloidiasis serodiagnosis.