| Abstract: | Four independently derived hybrids between the mouse fibroblast line A9 and the human, Burkitt-lymphoma-derived lymphoblastoid cell line Daudi were studied for the presence of the Epstein-Barr virus (EBV) genome, the EBV-determined nuclear antigen (EBNA), other EBV-associated antigens, human surface immunoglobulin and the presence of human chromosomes. The four lines differed in the number of their EBV genomes. There was a parallelism between this number, as detected by c/RNA/DNA hybridization, and the frequency of EBNA-positive nuclei. None of the other EBV-antigens, EA, VCA or MA, was expressed at any time, either in the untreated hybrid cells or after IUDR-treatment. The hybrids did not carry detectable surface-associated immunoglobulin or EBV-receptors. The presence of the EBV genome was coincident with the maintenance of human chromosomes, but the hybrids that have lost detectable viral genomes and EBNA still contained a considerable number of human chromosomes, suggesting that the viral genome may be associated with a few chromosomes only. |
