Development of tumours in mice chronically infected with herpes simplex virus.

Tumours developed in chronic infection lasting for 150--180 days in 39 (60%) of 65 mice infected with strain L2 of herpes simplex virus (HSV) type 1 and in 12 (20%) of 60 mice infected with strain 333 of HSV type 2. Similar results were obtained in 150 immunosuppressed mice chronically infected with HSV types 1 and 2. Pathomorphologically, the neoplasias in the first group (strain L2) were similar to adenocarcinoma and malignant lymphoma and in the second (strain 333) to lymphoma and angio- or fibrosarcoma. The respective HSV strains were isolated by cocultivation of blood leukocytes from chronically infected animals and cultures of the tumour cells with human embryo fibroblasts (HEF). HSV and Gross murine leukaemia virus antigens were detected in tumour cells by immunofluorescence and radioimmunoassay, respectively, and HSV antigen by immunofluorescence also in cultures of tumour cells and in cells of the brains, spinal cords, livers and spleens of the animals. HSV antibody was demonstrable in the blood serum from chronically infected tumour-bearing mice in a titre of 32.