SYNTHETIC PEPTIDES DEDUCED FROM THE AMINO-ACID-SEQUENCE OF EPSTEIN-BARR-VIRUS NUCLEAR ANTIGEN-6 (EBNA-6) - ANTIGENIC PROPERTIES, PRODUCTIONOF MONOREACTIVE REAGENTS, AND ANALYSIS OF ANTIBODY-RESPONSES IN MAN

Studies on the antibody responses to various Epstein-Barr vi rus (EBV) antigens have been instrumental in the understanding of the seroepide miology and diagnosis of this viral infection and the subsequent carri er state. While antibodies to the viral capsid antigen (VCA), early an tigen (EA), and nuclear antigens 1 and 2 (EBNA 1 and 2) have been well characterized, the antibody response to the other nuclear antigens is not well understood. EBNA 6 is expressed by lymphoblasts during acute EBV infection and may be an important antigen for diagnosis and evalu ation of the immune response. In order to analyze the antibody respons e to EBNA 6, ten peptides (20-21 amino acids), deduced from the EBNA 6 coding region, were synthesized and evaluated for antigenicity by ELI SA. One peptide (p-63; PAPQAPYQGYQEPPAPQAPY) derived from the amino ac id repeats showed the highest specific reactivity with human sera. Thi s peptide was evaluated further for detection of human EBNA 6-reactive antibodies. Forty-two of forty-nine (86%) EBV-seropositive healthy do nors had p-63-specific IgG reactivity, while none of 50 EBV-seronegati ve patients reacted with the p-63 peptide. Twenty-two of fifty-one (43 %) patients with ongoing primary EBV infection had detectable p-63-spe cific IgG. Serum samples drawn sequentially from patients during and a fter primary EBV infection revealed an increase in p-63-reactive IgG o ver time, A similar pattern was found for reactivity with an EBNA 1-sp ecific peptide (p-107), in contrast to the EBNA 2 (polyproline) respon se, which decreased over time. Some EBV-seropositive individuals who h ad no detectable IgG against peptide p-63 did have antibodies against the native EBNA 6 by anticomplement immunofluorescence to EBNA 6 trans fected cells. Rabbit antiserum raised against p-63 reacted specificall y with native EBNA 6 by an immunofluorescence assay and by immunoblott ing, indicating the EBNA 6-specific antigenicity of the peptide. Thus, the peptide p-63 derived from the amino acid repeats of the EBNA 6 co ding region constitutes a predominant, although not exclusive, epitope in the EBNA 6 antibody response. (C) 1995 Wiley-Liss, Inc.