Selection of high affinity peptide ligands for detection of circulating antibodies in neurocysticercosis

Neurocysticercosis (NC), caused by Taenia solium, is the most common infection caused by helminthes of the human central nervous system. In this study, a random peptide phage display library was used to isolate peptide ligands as potential markers for neurocysticercosis diagnosis, because occurrence of cross-reactions with other helminthes species in the current used markers. We selected different peptides using IgG purified from pooled sera of neurocysticercosis patients. To investigate the diagnostic potential of recombinant peptides, we have tested different panels of serum samples by Phage-ELISA, and 10 phage clones strongly bound to the anti-T. solium IgGs in NC sera, with an accuracy range from 84.2% to 95%. The phage clones, NC(4)1 and NC(2)8, presented the highest sensitivity and specificity (100%), respectively, and most important, some phage clones did not react with patients' sera from Echinococcus granulosus infected patients. The validation with a competitive ELISA assay demonstrated that the selected phages could mimic T. solium epitopes and bind specifically to the pool of NC sera. Finally, the two recombinant antigens may become potential biomarkers for serodiagnosis of NC, and the Phage-ELISA demonstrated to be a very good assay, being reproducible, simple, fast, and low-cost due to its production through Escherichia coli culture, allowing a high throughput screening of NC.