Detection of human serum antibodies to the BFRF3 Epstein-Barr virus capsid component by means of a DNA-binding assay.

A novel assay for antibodies to an immunodominant component of the Epstein-Barr virus (EBV) capsid antigen (VCA) complex was developed by creation of a chimeric protein containing the DNA-binding domain of the yeast GAL4 protein fused to the capsid antigen encoded by the BFRF3 gene of EBV. GAL4-BFRF3 antigen fusion protein bound specifically to a duplex DNA oligonucleotide containing GAL4-binding sites. Antibodies to the antigen were revealed by retardation of the electrophoretic mobility of the DNA-protein complex. Antibodies to the BFRF3 component of VCA became detectable approximately 2 months after onset of infectious mononucleosis. Kinetics of the antibody response to BFRF3 were identical using supershift or immunoblotting assays. Concordance between the DNA-binding assay and the classical indirect immunofluorescence assay for antibody to VCA was 97%. The GAL4 epitope assay is applicable for detection of antibodies to many cloned gene products.