Molecular size variation of EBNA is determined by the EB viral genome.

The size classes of the Epstein-Barr virus(EBV)-induced nuclear antigen (EB-NA) have been determined in EBV-carrying sublines of two originally EBV-negative Burkitt lymphomas, converted in vitro by two different EBV substrains, and in somatic hybrids between two EBV-carrying cell lines or between an EBV-positive and an EBV-negative line. Partially purified EBNA components were detected by Western blotting and subsequent exposure to antiserum/alkaline-phosphatase-coupled protein A complexes. Converted Ramos and BJAB sublines contained the main EBNA components characteristic for the virus donor strain. The EBNA components of the Ramos and BJAB cells converted by P3HR-1 virus were similar to each other and to the components of the P3HR-1 donor cell, whereas the EBNA of the cells converted by B95-8 virus resembled the B95-8 donor line. It was concluded that the size variation of EBNA is determined by the viral genome. The parental lines of the somatic hybrids studied (Raji, P3HR-1, Namalwa and Daudi) contained EBNA components of different molecular weight (MW) classes. The higher MW forms ranged from 70K to 80K. Several distinctive lower MW components also were present. The somatic hybrids expressed the main EBNA components of both parental lines. Hybrids between EBV-carrying and EBV-genome-negative lines contained the characteristic EBNA component of the EBV-positive parent. It was concluded that the size variation of EBNA is under strict genetic control which prevails in the hybrids in a codominant fashion.