Induction of Tumors by a Virus-Like Agent(s) Released by Tissue Culture

Abstract

This report confirms and extends by using essentially newborn inbred strains of mice (dba/1, C57Black/Ha, Swiss/ICR-Ha, AKR/Sn, AKR x Swiss F1) rats and hamsters (newborn and 14 days old), the recent observations of Drs. Stewart and Eddy (1957, 1958) relative to the induction of multiple types of tumors with a virus-like agent (s) derived from a mouse parotid tumor propagated in mouse embryo tissue culture. The virus-like agent, SE Polyoma Virus, present in filtered tissue culture fluids, is unique because it ignores strain and species barriers. Hamsters are very susceptible to the agent (s); the average tumor latent period is 29 days, although tumors can be seen as early as 15 days. The average tumor Latent period for mice and rats is 75 and 180 days respectively. Although rigid precautions in technique are observed, the virus-like agent (s) can contaminate control tissue culture fluid as determined by assay in injected animals. Transplantation of some of the induced tumors occurring in inbred mouse strains has been successful into the strain of origin if newborn and preconditioned hosts are used. In the rat the sarcoma of kidney is transplantable and Ls presently in its Fa transplantable generation. The virus-like agent can be recovered from all transplantable tumors.