Depression of Rauscher leukemia virus envelope glycoprotein gp71 binding by lymphoid cells during leukemogenesis in mice.

The availability of membrane receptors for the 71,000-dalton envelope glycoprotein (gp71) of Rauscher murine leukemia virus on splenic and thymic cells from BALB/c mice during Rauscher murine leukemia virus-induced leukemogenesis was determined utilizing a radiolabeled gp71 binding assay. Shortly after infection, the relative cellular [125I]gp71 binding level decreased, first with splenic cells (at day 7 to 10 after infection) and later with thymic cells (at day 10 to 20 after infection). The dependency of the reduction of binding on the replication of the inoculated virus was demonstrated by regression analyses using cellular gp71 binding level as the dependent variable and infectious virus titer, as well as viral gp71 and p30 levels, of spleens and thymuses from infected mice as independent variables. With each independent variable, the reduction of gp71 binding for both cell types was highly dependent (P less than 0.01) on the level of virus detected in their respective organ. In the early stages of leukemogenesis, the [125I]gp71 binding level declined to approximately 20 to 30% of control values. During this period the rate of reduction of binding was very rapid and, in general was similar for both splenic and thymic cells. Further progression of the disease resulted in little or no further reduction in binding. The application of this technique to monitor host ecotropic virus synthesis and to study cell surface virus receptor control mechanisms in vivo is discussed.