Induction of tumors by a guinea pig herpesvirus-transformed hamster cell line

Syrian hamster embryo cells that had been transformed in vitro by guinea pig herpes-like virus (GPHLV) were found to be oncogenic when inoculated into hamster sc or ip. Of 71 animals inoculated, 30 showed tumors at the site of inoculation. Tumors appeared 4-23 weeks after inoculation of the transformed cells at passage 37 or higher. Inbred and randombred hamsters of all ages were susceptible. Upon microscopic examination the tumors were characterized as fibrosarcomas. The cultured hamster tumor cells were easily transplanted into hamsters, but produced no evidence of tumors when inoculated into guinea pigs. Infectious GPHLV was not isolated from the tumor cells, but GPHLV-specific surface antigens were detected in tumor cells by immunofluorescence of GPHLV antiserum produced in rabbits. Sera from tumor-bearing hamsters did not contain GPHLV-neutralizing antibodies, but sera from 4 of 23 hamsters bearing primary tumors and 12 of 41 bearing transplanted tumors produced nuclear fluorescence in cells infected with GPHLV, thus establishing the relationship between the guinea pig herpesvirus and the hamster tumors.