GENE-MAPPING AND EXPRESSION OF 2 IMMUNODOMINANT EPSTEIN-BARR-VIRUS CAPSID PROTEINS

The genomic localization of two immunodominant genes encoding two prot eins of the Epstein-Barr virus capsid antigen (VCA) complex, VCA-p18 a nd VCA-p40, has been identified. For that purpose, lambda gt11-based c DNA libraries were constructed from HH514.c16 cells induced for virus production. The libraries were screened with a monoclonal antibody, EB V.OT41A, directed against VCA-p40 or with affinity-purified human anti bodies against VCA-p18. Sequencing of the inserts of positive plaques showed that VCA-p18 and VCA-p40 are encoded within open reading frames (ORFs) BFRF3 and BdRF1, respectively. Peptide scanning analysis of th e predicted protein of ORF BdRF1 resulted in defining the epitope of m onoclonal antibody EBV.OT41A at the C-terminal region. The dominant VC A-p18 reactivity of human sera can be completely inhibited by preadsor ption with Escherichia coli-expressed BFRF3-beta-galactosidase. Serum of a rabbit immunized with BFRF3-betagalactosidase reacts with a VCA-s pecific protein of 18 kDa. In addition, BFRF3-beta-galactosidase affin ity-purified antibodies react with VCA-p18 of virus-producing cells (H H514.c16). Complete inhibition of viral DNA polymerase activity by pho sphonoacetic acid is associated with the absence of RNAs and protein p roducts of both ORFs, indicating that VCA-p18 and VCA-p40 are true lat e antigens.