Epstein-Barr Virus Nuclear Antigen (EBNA): Size Polymorphism of EBNA 1

The mol. wt. of the polymorphic Epstein-Barr virus (EBV) nuclear antigen (EBNA) molecule (EBNA 1) encoded by the BamHI K fragment of the EBV DNA has been determined in 14 EBV-carrying lymphoblastoid and Burkitt's lymphoma cell lines. There is no obvious correlation between the size of this polypeptide and any properties of the cells from which it is derived, other than those related to the strain of transforming virus. We confirm that the polymorphic region of this molecule is the glycine-alanine copolymer encoded by the third internal repeat of the EBV genome (IR3) and we consider the significance of this domain. The Epstein-Barr virus (EBV) nuclear antigen (EBNA) was first demonstrated in EBV-transformed cells by a complement-enhanced immunofluorescence assay, ACIF (Reedman & Klein, 1973). Recently, it has been shown that EBNA, as demonstrated by ACIF using polyspecific human antisera, is not a single entity but rather a complex of at least two and possibly more antigenic omponents. The major component has been identified as a polypeptide encoded by the large HindlII subfragment of the BamHI K fragment of the EBV genome (Hennessy & Kieff, 1983; Fischer et al., 1984; our unpublished ata). This molecule apparentl