Relationship of virulent and attenuated rna oncogenic virus antigens to surface antigens of the virus‐transformed cell: Implications for the reverse transcriptase system, the provirus, protovirus and oncogene theories of neoplasia, and the lmmunoprophylaxis of RNA virus‐induced tumors

Immunization with Rauscher leukemia virus resulted in high antibody levels against the virustransformed malignant cell. As expected, antibody to malignant cells followed immunization with standard virus preparations highly contaminated with cell membranes. Surprisingly, good antibody levels to malignant cells also followed immunization with highly purified virus, electron microscopically free of cell membranes. The antibody response to malignant cells paralleled the antibody response to the virus, under a variety of conditions. Immunization of mice with formalin‐inactivated virus preparations, contaminated with cell membranes, resulted in protection of the mice against subsequent challenge with malignant cells. In addition, good immunity to malignant cells followed immunization with live, attenuated Rauscher virus, which was harvested from nonmalignant cells. This attenuated virus produced no malignancy after inoculation and presumably contains only viral antigens, and no malignant cell antigens. These studies strengthen the evidence that Rauscher virus is the “tumor specific transplantation antigen” on the surface of the Rauscher malignant cell. Rauscher virus is presumably integrated into the cell surface membranes which are, therefore, likely sites for transmission of cell enzymes and other proteins into the virus particle. This transfer of material from cell surface to virus particle may explain the Increasing number of enzymes, including “reverse transcriptases,” which have been isolated from RNA tumor viruses. Some such mechanism must be invoked because these viruses do not have sufficient nucleic acid to code for all the “virus‐associated” enzymes.