Alteration of cellular ribonucleases associated with murine oncogenic virus infection

The ribonuclease activity of peripheral lymphocytes from Balb/c mice was studied at various intervals subsequent to infection of mice by oncornavirus. Lymphocytes from mice infected with Friend leukemia virus possessed elevation of RNase activity within 8 days subsequent to infection. Balb/c mice infected with Moloney sarcoma virus demonstrated an analogous elevation of RNase activity with 7-9 days postinfection. Diminishment of cellular RNase activity occurred in the Friend leukemia model concomitant to the occurrence of significant numbers of erythroblasts in the peripheral blood, while ribonuclease activity in lymphocytes from mice infected with Molney sarcoma virus returned to normal 1-2 weeks subsequent to host rejection of tumor. It is concluded that elevation of RNase activity within the lymphocyte represents an early event in oncogenic viral infection within these two tumor models. The possible meaning of elevation of RNase activity is a target (the lymphocyte) not predestined to undergo neoplastic transformation is discussed.