Immunogenicity evaluation of viral peptides via non-specific interactions between anti-peptide IgYs and non-cognate peptides.

Immunogenicity can be evaluated by detecting antibodies induced by an antigen. Presently deployed assays, however, do not consider the negative impacts of antibody poly-specificity, which is well-established at the monoclonal antibody level. Here, we studied antibody poly-specificity at the serum level (i.e., non-specific Antibody (Ab)-probe interactions, NSIs), and ended up with establishing a new platform for viral peptide immunogenicity evaluation. We first selected three peptides of high, medium, and low immunogenicity, using "vaccine serum response rate"-based approach (i.e., the gold standard). These three peptides (Pi) in the bovine serum albumin (BSA)-Pi form were used to immunize chickens, resulting longitudinal serum samples for screening with non-cognate peptide library. The signal intensity of Ab-peptide specific binding and "NSI count" were used to evaluate the viral peptides' immunogenicity. Only NSI count agreed with the gold standard. NSI count also provides more informative data on antibody production than the aggregated signal intensity by whole-protein-based indirect enzyme linked immunosorbent assay (iELISA).