Herpes simplex virus type 2 rendered defective by ultraviolet irradiation transformed hamster embryo fibroblasts in vitro. When the transformed cells were inoculated into newborn hamsters, solid tumors developed and cell cultures were established. The virus-transformed cells, the solid tumors, and the tumor cell cultures were examined by electron microscopy. The transformed cultures and tumors contained cells with nuclei in which the chromatin had become condensed and marginated; this picture resembled the cytopathology induced during lytic infection by herpes simplex virus. These abnormalities were observed in some cell culture lines established from the tumors. Virus-like particles, similar in size and morphology to nonenveloped herpesvirus, were found in the nuclei of a small number of degenerating cells in some of the specimens examined.
This investigation was supported under Contract 70-2024 within the Special Virus-Cancer Program of the National Cancer Institute, NIH, USPHS.