Peptide mimotopes selected from a random peptide library for diagnosis of Epstein-Barr virus infection

Epstein-Barr virus (EBV) is a ubiquitous, worldwide infectious agent that causes infectious mononucleosis, affecting >90% of the world's population. Currently, enzyme-linked immunosorbent assay, mostly with purified preparations of EBV cell extracts to capture immunoglobulin M (IgM) antibodies in patients' serum, is used for primary diagnosis. Our objective was to determine whether a small set of peptides could contain sufficient immunogenic information to replace solid-phase antigens in EBV diagnostics. Using monoclonal antibodies, we selected four peptides that mimic different epitopes of EBV from a phage-displayed random peptide library. To assess their diagnostic value, we screened a panel of 62 individual EBV IgM sera for their reactivities with the peptides alone. For all peptides, there was a clear distinction between the EBV-positive and the EBV-negative samples, resulting in 100% specificity. The sensitivities were 88%, 85%, 71%, and 54% for peptides F1, A3, gp125, and A2, respectively. Any combination of peptides increased the sensitivity, indicating that individual peptides react with different subsets of antibodies. Furthermore, when the F1 and the gp125 peptides were coupled to bovine serum albumin and screened against 216 serum samples, there were dramatic improvements in sensitivities (95% and 92%, respectively) and little cross-reactivity with the other peptides encountered during acute viral infections, including rheumatoid factor. This study shows the potential for the use of peptide mimotopes as alternatives to the complex antigens used in current serodiagnostics for EBV infection.