Antibodies to an Epstein-Barr virus nuclear antigen synthetic peptide in infectious mononucleosis. Report of two cases.

The Epstein-Barr virus nuclear antigen (EBNA-1) contains a region of repeating glycine and alanine amino acids. It has been shown that this region contains a major epitope of EBNA-1. With well-characterized sequential sera from two cases of acute infectious mononucleosis, a specific IgM response was detected to the EBNA-1 synthetic peptide by enzyme-linked immunosorbent assay (ELISA). Conversely, an IgG response was observed in the convalescent phase of the illness with a progressive decline of the IgM antibodies. This response was observed with heterophil-positive and heterophil-negative EBV/IM. The peptide-specific serologic response was confirmed by immunoblotting, the serial serum samples on extracts of EBV transformed B-cells. There was excellent correlation between the antipeptide ELISA and blotting techniques.