Transformation of Hamster Embryo Fibroblasts by Herpes Simplex Viruses

Hamster embryo fibroblast cells can be transformed after infection by ultraviolet light-irradiated herpes simplex viruses type 1 (HSV-1) or type 2 (HSV-2). Two ofl2 strains of HSV-1 and 7 of 15 strains of HSV-2 induced cell transformation. Transformed cells from two strains of HSV-2 and one strain of HSV-1 have been tested for oncogenicity in newborn Syrian hamsters. One cell line transformed by HSV-2 strain 333 was found to be oncogenic. The remaining two cell lines were not oncogenic. Herpesvirus antigens were found in the cytoplasm and on the surface of the transformed cells. Neutralizing antibodies were produced in hamsters developing tumors after the injection of the HSV-2-transformed cells. Weanling ham sters that were preimmunized by injection of HSV-1 or HSV-2 did not develop transplantation immunity to the HSV-2-transformed cells as a result of this preimmunization. HSV-2-transformed cells metastasized after injection into hamsters. The number of métastaseswas not inhibited by HSV-1 or HSV-2 immunization but was actually enhanced. Immunization of hamsters with simian virus 40 inhibited métastasesbut did not reduce the rate of primary tumor development.