Induction of Tumors in Rats by Tissue-Culture Preparations of SE Polyoma Virus

Abstract

Sixty-five newborn Sprague-Dawley rats were inoculated with SE polyoma virus that had been propagated in mouse-embryo tissue cultures. Eighteen of the rats developed renal sarcomas and 7, subcutaneous tumors. A tissue mince of renal sarcoma and spleen from a rat with an induced kidney tumor was used as an initial inoculum for a series of mouse-embryo tissue cultures. The culture fluid from the fourth serial passage induced visceral tumors in hamsters like those produced by previous tissue-culture lines of the SE polyoma virus. The fluid from this culture after 12 serial passages again induced renal sarcomas in rats. The rat is the third mammalian species to develop significant numbers of tumors after receiving, in the newborn period, SE polyoma virus grown in tissue culture.