Athymic nude mice: induction of tumors containing Epstein-Barr virus using Burkitt's-related cell lines

We studied tumor induction in athymic nude mice by D98/HR-1 cells, an epithelial somatic cell hybrid containing the Epstein-Barr virus (EBV) genome, and by the parental D98 and HR-1 cells. Groups of animals were inoculated with cells grown in culture, with cells from tumors induced by the cell lines, or with cells from lines derived from tumors. The tumors induced by D98/HR-1 cells were undifferentiated carcinomas; those induced by D98 cells were carcinomas and those induced by HR-1 cells were poorly differentiated lymphomas. Preliminary data suggest that the number of EBV genome equivalents was sharply reduced in cells from both D98/HR-1 and HR-1 tumors. Subsequent passage of tumor cells in vitro resulted in a partial recovery in the number of EBV genome equivalents in HR-1 cells and a complete recovery in D98/HR-1 cells. The reduction in the number of EBV genomes in the tumor cells suggests that in vitro passage can influence the number of EBV genomes in these cells.