Malignant Transformation and Immortalization Assays in Animal Cells Transfected with the BARF1 Gene

Epstein-Barr virus (EBV) is associated with both lymphoma (for example, Burkitt’s lymphoma) and epithelial carcinoma (for example, nasopharyngeal carcinoma). Among about 90 genes encoded by the virus (1 ), seven latent genes—(Epstein-Barr viral nuclear antigen 1 (EBNA1), EBNA2, EBNA3A, EBNA3C, latent membrane protein 1 (LMP1), and EBERs—were found to be indispensable for B cell immortalization (2 ). LMP1 induces malignant transformation in rodent cell lines such as Rat-1 cells (3 ) and Balb/c3T3 cells (4 ), whereas EBNA1 was recently reported to induce lymphomas in transgenic mice (5 ). An early lytic viral gene, BARF1, was identified to have oncogenic activity in a rodent fibroblast cell line (6 ) and in the human B cell line, Louckes (7 ).