Oncogenic Potential of Murine C-Type RNA Virus Passaged Directly from Naturally Occurring Tumors of the BALB/cCr Mouse

Summary

A study of the oncogenic potential of murine C-type RNA virus passaged directly from naturally occurring tumors of the BALB/cCr mouse is described. A total of 1954 BALB/cCr mice were inoculated at birth with 141 viral preparations and observed up to 24 months. The viral inocula were obtained from spontaneous tumors of various histologic types, including lymphoreticular, mammary, sarcoma-tous, and benign types. Of these tumors, 51% yielded isolatable virus. Significant induction of lympho-reticular (LR) neoplasms was observed in animals given virus-positive inocula, rather than virus-negative of no inocula. Solid non-LR neoplasms that occur naturally in the BALB/cCr mouse were not induced, The histologic type of donor tumor that the viral inocula were derived from and the route of inoculation did not affect these observations. The mean latent period of LR neoplasm induction was quite long (469 days), but was significantly different (P<0.05) from that of naturally occurring LR neoplasms (634 days). Results were discussed in light of the oncogene hypothesis.