Some Biologic, Immunogenic, and Morphologic Effects in Mice After Infection With a Murine Sarcoma Virus. I. Biologic and Immunogenic Studies

Abstract

Murine sarcoma virus (MSV, Moloney) induced relatively few progressively growing tumors after intramuscular injections into C57BL/-KaLw (BALB/c × DBA/2)F₁, and (C57BL/Ka × C3H/Lw)F₁ mice. Thymectomy at 3 days of age in these mice, however, increased the frequency of progressively growing tumors resulting in death. The age of susceptibility to MSV was greatly lengthened. Even in thymectomized mice many primary tumors regressed after growing as large as 20–30 mm in diameter. Regressions were also common in some strains of mice given injections during the neonatal period. The usual tumor at the site of injection contained varying numbers of atypical cells, probably neoplastic, but was composed mostly of reactive granulation tissue. These tumors are designated “atypical granulomas.” All those tested released infectious MSV. Similar histopathologic lesions were induced by the in vivo- and in vitro-passaged MSV and by the “rescued” pseudotype, MSV (Rauscher leukemia virus), given at varying concentrations. The atypical granulomas did not grow progressively when transplanted to adult syngeneic recipients. Sublethal X irradiation or 3-day thymectomy of syngeneic adults before tumor transplantation resulted in progressive growths. The use of irradiated recipients for successive passages of atypical granulomas established 3 neoplasms as hemangiosarcomas; these then had the capacity to grow progressively in intact adult syngeneic hosts. In contrast to the atypical granulomas, the neoplasms release little, if any, infectious MSV. Complete resistance to transplantation of an atypical granuloma in irradiated syngeneic hosts was elicited by MSV, Moloney leukemogenic virus, and those MSV-induced tumors releasing infectious virus. Passive transfer of resistance was achieved by an effective anti-MSV serum. A relationship between antibody production and MSV oncogenesis is also suggested.