Further studies on growth characteristics of Epstein-Barr virus (EBV) genome-positive and -negative epithelial hybrid cell lines.

Differences in tumorigenicity between the Epstein-Barr virus (EBV) genome-negative and -positive epithelial A2L/AH hybrid cell lines have been described recently. Further differences in growth characteristics of the two epithelial hybrid cells have since been examined. Differences were found in doubling time and cloning efficiency in agarose of the two cell lines. In addition, the EBV genome-negative epithelial hybrid cell line (cl-654), unlike the EBV genome-positive epithelial hybrid cell line (cl-1), failed to grow in the unmanipulated nude mice, but was successfully transplanted in 60Co-irradiated nude mice. The histopathologic findings of tumors induced by the inoculation of cl-654 cells in nude mice showed more differentiated carcinoma than the findings of tumors induced by cl-1 cells. The data suggest that EBV is associated with an alteration of cell differentiation in epithelial cells as well as tumorigenicity in nude mice.