Specificity of Resistance to Tumor Challenge of Polyoma and SV 40 Virus-Immune Hamsters.

Abstract

Zilber and his associates(1) were the first to demonstrate an abnormal antigen in a virus-induced tumor when they worked with Rous sarcoma. More detailed studies of the relationships between the inducing virus and the new cellular antigen in the transformed cells were later made by Klein and his associates(2), and by Habel(3), using polyoma virus-induced tumors in the mouse and the hamster. Since that time there has rapidly appeared published evidence for the existence of new cellular antigens in Gross leukemia cells(4), Shope papilloma virus tumors(5), and Moloney virus leukemia(6). The biological method which most readily demonstrated the new antigen in polyoma tumors, tested the resistance of virus immunized adult animals to challenge with isologous transplantable polyoma tumor. This same technic has been used to demonstrate new cellular antigens in SV 40 virus induced hamster tumors in the experiments reported here.

The original work with polyoma tumors had demonstrated the specificity of the new antigen insofar as there was no cross resistance by polyoma immune mice against challenge with tumors induced by other oncogenic agents. SV 40 and polyoma viruses have several physical and chemical characteristics in common(7). They are both DNA viruses of the same size, both have the same number of capsomeres, and both produce sarcomas on inoculation of newborn hamsters. For this reason it was felt that a cross-immunity test, in which animals immunized with each of these 2 viruses were challenged with the corresponding tumors, would be a more severe and direct test of the specificity of the new virus-induced cellular antigens. It will be shown that in such a cross-immunity test each virus appears to induce a resistance to tumor challenge which is quite specific.

Materials and methods. Viruses. Polyoma virus was grown in mouse embryo tissue culture from random-bred Swiss mice and a standard pool had a titer of 1.5 × 10⁷ pfu/ml. SV 40 virus was grown in primary green monkey kidney tissue cultures and had a titer of 4 × 10⁷ TCID₅₀ per ml. Antiviral antibody.