Role of antibodies to murine leukemia virus p15E transmembrane protein in immunotherapy against AKR leukemia: a model for studies in human acquired immunodeficiency syndrome.

Previous studies have demonstrated that the onset of AKR leukemia could be dramatically delayed and the overall incidence significantly reduced following treatment with high-titered heterologous antibodies directed against the gp71 major glycoprotein of the virus. However, to be maximally successful, the treatment had to be initiated during the postnatal period of the AKR mouse, encompassing a narrow window representing approximately the first 3 days of life. In the present study we sought to extend this barrier by including antibodies directed against a second envelope component of the virion, the transmembrane protein, p15E. We demonstrate that although neither antibodies to gp71 nor antibodies to p15E could influence the course of leukemia development when applied individually later in life, a combination of the two antibodies was effective even if given as late as 5 months after birth. The significance of these studies is discussed in relation to human retrovirus-associated diseases.