Comparison of Simian Virus 40-Induced Mouse and Hamster Tumor-Specific Transplantation Antigens2

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Abstract
The tumor-specific transplantation antigen (TSTA), which appears on papovavirus-induced sarcomas of the hamster, has been demonstrated to be common in any cell type transformed by a given virus. Other studies have suggested that cell-free TSTA has been successfully Isolated from mouse sarcoma cells Induced in vitro by simian virus 40 (SV40). Considerable work has been done toward purifying and identifying this mouse TSTA. We obtained preparations from the laboratory reporting the isolation of TSTA from the SV40-induced mouse sarcoma cells as well as cell lines from which the preparations of TSTA had been derived. These extracts, as well as fresh extracts made from the appropriate SV40-induced mouse tumor line, were tested for their ability to Interrupt tumor production in mice after challenge with homologous and heterologous sarcomas and to prevent SV40 primary tumor induction in hamsters. The findings indicated that TSTA extracted from SV40-induced mouse sarcoma cells as well as from the intact irradiated mouse sarcoma cells failed to prevent SV40 oncogenesis as well as tumor transplantation in the hamster, but It was capable of preventing specific tumor transplantation when used as a vaccine in mice. Human and hamster cells transformed by SV40 were capable of interrupting SV40 oncogenesis in the hamster. These results suggested that the so-called TSTA, which is immunogenic and induces specific transplantation resistance in mice to SV40-in-duced mouse sarcomas, was not the same TSTA that appears on human, rat, and hamster cells and that is produced by SV40 in those cell types. Further, tumor antigen may be the immunizing component which others have isolated as a transplantation-like antigen from mouse sarcoma cells. An alternative explanation would be a peculiar histocompatibility (H-2) barrier in the hamster to the immunogenicity of TSTA induced in mouse cells.