Louise S. Rabstein

Murine C-type RNA virus from spontaneous neoplasms: in vitro host range and oncogenic potential.

Strain BALB/c mice harbor at least two host range variants of marine leukemia virus. One variant, which is host-cell tropic, is the predominant isolate from neoplastic tissues and produced lymphoreticular neoplasms when injected into BALB/c newborn mice. A second variant, whicht is isolated throughout life, grows poorly in host embryonic cells in culture and was not associated with lymphoreticular neoplasm induction when injected into newborn BALB/c mice.

Neoplastic Transformation and Derivation of a Focus-Forming Sarcoma Virus in Cultures of Rat Embryo Cells Infected with a Murine Osteosarcoma (FBJ) Virus

Summary Neoplastic transformation of rat embryo cells in vitro by an osteosarcoma (FBJ) virus is reported. Foci of transformed cells consisted largely of spindle-shaped cells which stained vividly with acridine orange. The transformed cells produced virus and complement-fixing (CF) antigen characteristic of the murine leukemia-sarcoma virus complex. Tumors were produced when transformed cells were injected into newborn mice and rats. The mouse tumors had the histologic pattern of osteosarcoma, which was transmissible in cell-free passages in newborn mice. Cell-free extracts of the mouse tumors also produced transformed foci in vitro. The rat rumors were undifferentiated sarcomas, also yielding virus and CF antigens.

Effects of Thymectomy, Splenectomy and 3-Methylcholanthrene on Neoplasia Expression, Incidence and Latency in AKR Mice

Summary The effects of thymectomy, splenectomy and 3MC treatment on neoplastic expressions were studied in AKR mice. In the intact and splenectomized mice, 3MC increased the total incidence of neoplastic expression due to the development of sc tumors at the site of 3MC treatment and not to an increase in incidence of leukemia. Thymectomy eliminates leukemia during the nine-month observation period in the trioctanoin vehicle control mice and reduced the incidence of leukemia to 1/18 in the 3MC treated mice. The incidence of 3MC induced sarcomas was not increased by thymectomy even in the absence of leukemia, therefore the total incidence of neoplasia was reduced from 100% to 56%. Both thymectomy and splenectomy reduced the latency period for 3MC sarcoma induction.